{"id":4911,"date":"2020-12-23T19:44:24","date_gmt":"2020-12-23T11:44:24","guid":{"rendered":"https:\/\/damogame.cn\/wordpress\/?p=4911"},"modified":"2024-01-03T19:27:32","modified_gmt":"2024-01-03T11:27:32","slug":"linux-i-o-%e5%8e%9f%e7%90%86%e5%92%8c-zero-copy-%e6%8a%80%e6%9c%af%e5%85%a8%e9%9d%a2%e6%8f%ad%e7%a7%98","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/4911","title":{"rendered":"Linux I\/O \u539f\u7406\u548c Zero-copy \u6280\u672f\u5168\u9762\u63ed\u79d8"},"content":{"rendered":"<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><a href=\"https:\/\/mp.weixin.qq.com\/s\/dZNjq05q9jMFYhJrjae_LA\">\u539f\u6587\u5730\u5740<\/a><\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f5c\u8005\uff1aallanpan\uff0c\u817e\u8baf IEG \u540e\u53f0\u5f00\u53d1\u5de5\u7a0b\u5e08<\/p>\n<blockquote data-tool=\"mdnice\u7f16\u8f91\u5668\"><p>\u4e24\u4e07\u5b57\u957f\u6587\u4ece\u865a\u62df\u5185\u5b58\u3001I\/O \u7f13\u51b2\u533a\uff0c\u7528\u6237\u6001&amp;\u5185\u6838\u6001\u4ee5\u53ca I\/O \u6a21\u5f0f\u7b49\u7b49\u77e5\u8bc6\u70b9\u5168\u9762\u800c\u53c8\u8be6\u5c3d\u5730\u5256\u6790 Linux \u7cfb\u7edf\u7684 I\/O \u5e95\u5c42\u539f\u7406\uff0c\u5206\u6790\u4e86 Linux \u4f20\u7edf\u7684 I\/O \u6a21\u5f0f\u7684\u5f0a\u7aef\uff0c\u8fdb\u800c\u5f15\u5165 Linux Zero-copy \u96f6\u62f7\u8d1d\u6280\u672f\u7684\u4ecb\u7ecd\u548c\u539f\u7406\u89e3\u6790\uff0c\u5c06\u96f6\u62f7\u8d1d\u6280\u672f\u548c\u4f20\u7edf\u7684 I\/O \u6a21\u5f0f\u8fdb\u884c\u533a\u5206\u548c\u5bf9\u6bd4\uff0c\u5e2e\u52a9\u8bfb\u8005\u7406\u89e3 Linux \u5185\u6838\u5bf9 I\/O \u6a21\u5757\u7684\u4f18\u5316\u6539\u8fdb\u601d\u8def\u3002\u5168\u7f51\u6700\u6df1\u5ea6\u548c\u8be6\u5c3d\u7684 Linux I\/O \u53ca\u96f6\u62f7\u8d1d\u6280\u672f\u7684\u89e3\u6790\u6587\u7ae0<\/p><\/blockquote>\n<h3 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5bfc\u8a00<\/h3>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5982\u4eca\u7684\u7f51\u7edc\u5e94\u7528\u65e9\u5df2\u4ece CPU \u5bc6\u96c6\u578b\u8f6c\u5411\u4e86 I\/O \u5bc6\u96c6\u578b\uff0c\u7f51\u7edc\u670d\u52a1\u5668\u5927\u591a\u662f\u57fa\u4e8e\u00a0<code>C-S<\/code>\u00a0\u6a21\u578b\uff0c\u4e5f\u5373\u00a0<code>\u5ba2\u6237\u7aef - \u670d\u52a1\u7aef<\/code>\u00a0\u6a21\u578b\uff0c\u5ba2\u6237\u7aef\u9700\u8981\u548c\u670d\u52a1\u7aef\u8fdb\u884c\u5927\u91cf\u7684\u7f51\u7edc\u901a\u4fe1\uff0c\u8fd9\u4e5f\u51b3\u5b9a\u4e86\u73b0\u4ee3\u7f51\u7edc\u5e94\u7528\u7684\u6027\u80fd\u74f6\u9888\uff1aI\/O\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f20\u7edf\u7684 Linux \u64cd\u4f5c\u7cfb\u7edf\u7684\u6807\u51c6 I\/O \u63a5\u53e3\u662f\u57fa\u4e8e\u6570\u636e\u62f7\u8d1d\u64cd\u4f5c\u7684\uff0c\u5373 I\/O \u64cd\u4f5c\u4f1a\u5bfc\u81f4\u6570\u636e\u5728\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u5730\u5740\u7a7a\u95f4\u7684\u7f13\u51b2\u533a\u548c\u7528\u6237\u8fdb\u7a0b\u5730\u5740\u7a7a\u95f4\u5b9a\u4e49\u7684\u7f13\u51b2\u533a\u4e4b\u95f4\u8fdb\u884c\u4f20\u8f93\u3002\u8bbe\u7f6e\u7f13\u51b2\u533a\u6700\u5927\u7684\u597d\u5904\u662f\u53ef\u4ee5\u51cf\u5c11\u78c1\u76d8 I\/O \u7684\u64cd\u4f5c\uff0c\u5982\u679c\u6240\u8bf7\u6c42\u7684\u6570\u636e\u5df2\u7ecf\u5b58\u653e\u5728\u64cd\u4f5c\u7cfb\u7edf\u7684\u9ad8\u901f\u7f13\u51b2\u5b58\u50a8\u5668\u4e2d\uff0c\u90a3\u4e48\u5c31\u4e0d\u9700\u8981\u518d\u8fdb\u884c\u5b9e\u9645\u7684\u7269\u7406\u78c1\u76d8 I\/O \u64cd\u4f5c\uff1b\u7136\u800c\u4f20\u7edf\u7684 Linux I\/O \u5728\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u7684\u6570\u636e\u62f7\u8d1d\u64cd\u4f5c\u6df1\u5ea6\u4f9d\u8d56 CPU\uff0c\u4e5f\u5c31\u662f\u8bf4 I\/O \u8fc7\u7a0b\u9700\u8981 CPU \u53bb\u6267\u884c\u6570\u636e\u62f7\u8d1d\u7684\u64cd\u4f5c\uff0c\u56e0\u6b64\u5bfc\u81f4\u4e86\u6781\u5927\u7684\u7cfb\u7edf\u5f00\u9500\uff0c\u9650\u5236\u4e86\u64cd\u4f5c\u7cfb\u7edf\u6709\u6548\u8fdb\u884c\u6570\u636e\u4f20\u8f93\u64cd\u4f5c\u7684\u80fd\u529b\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">I\/O \u662f\u51b3\u5b9a\u7f51\u7edc\u670d\u52a1\u5668\u6027\u80fd\u74f6\u9888\u7684\u5173\u952e\uff0c\u800c\u4f20\u7edf\u7684 Linux I\/O \u673a\u5236\u53c8\u4f1a\u5bfc\u81f4\u5927\u91cf\u7684\u6570\u636e\u62f7\u8d1d\u64cd\u4f5c\uff0c\u635f\u8017\u6027\u80fd\uff0c\u6240\u4ee5\u6211\u4eec\u4e9f\u9700\u4e00\u79cd\u65b0\u7684\u6280\u672f\u6765\u89e3\u51b3\u6570\u636e\u5927\u91cf\u62f7\u8d1d\u7684\u95ee\u9898\uff0c\u8fd9\u4e2a\u7b54\u6848\u5c31\u662f\u96f6\u62f7\u8d1d(Zero-copy)\u3002<\/p>\n<h3 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8ba1\u7b97\u673a\u5b58\u50a8\u5668<\/h3>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u65e2\u7136\u8981\u5206\u6790 Linux I\/O\uff0c\u5c31\u4e0d\u80fd\u4e0d\u4e86\u89e3\u8ba1\u7b97\u673a\u7684\u5404\u7c7b\u5b58\u50a8\u5668\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5b58\u50a8\u5668\u662f\u8ba1\u7b97\u673a\u7684\u6838\u5fc3\u90e8\u4ef6\u4e4b\u4e00\uff0c\u5728\u5b8c\u5168\u7406\u60f3\u7684\u72b6\u6001\u4e0b\uff0c\u5b58\u50a8\u5668\u5e94\u8be5\u8981\u540c\u65f6\u5177\u5907\u4ee5\u4e0b\u4e09\u79cd\u7279\u6027\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u901f\u5ea6\u8db3\u591f\u5feb\uff1a\u5b58\u50a8\u5668\u7684\u5b58\u53d6\u901f\u5ea6\u5e94\u5f53\u5feb\u4e8e CPU \u6267\u884c\u4e00\u6761\u6307\u4ee4\uff0c\u8fd9\u6837 CPU \u7684\u6548\u7387\u624d\u4e0d\u4f1a\u53d7\u9650\u4e8e\u5b58\u50a8\u5668<\/section>\n<\/li>\n<li>\n<section>\u5bb9\u91cf\u8db3\u591f\u5927\uff1a\u5bb9\u91cf\u80fd\u591f\u5b58\u50a8\u8ba1\u7b97\u673a\u6240\u9700\u7684\u5168\u90e8\u6570\u636e<\/section>\n<\/li>\n<li>\n<section>\u4ef7\u683c\u8db3\u591f\u4fbf\u5b9c\uff1a\u4ef7\u683c\u4f4e\u5ec9\uff0c\u6240\u6709\u7c7b\u578b\u7684\u8ba1\u7b97\u673a\u90fd\u80fd\u914d\u5907<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f46\u662f\u73b0\u5b9e\u5f80\u5f80\u662f\u6b8b\u9177\u7684\uff0c\u6211\u4eec\u76ee\u524d\u7684\u8ba1\u7b97\u673a\u6280\u672f\u65e0\u6cd5\u540c\u65f6\u6ee1\u8db3\u4e0a\u8ff0\u7684\u4e09\u4e2a\u6761\u4ef6\uff0c\u4e8e\u662f\u73b0\u4ee3\u8ba1\u7b97\u673a\u7684\u5b58\u50a8\u5668\u8bbe\u8ba1\u91c7\u7528\u4e86\u4e00\u79cd\u5206\u5c42\u6b21\u7684\u7ed3\u6784\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"img_loading\" src=\"data:image\/gif;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQImWNgYGBgAAAABQABh6FO1AAAAABJRU5ErkJggg==\" crossorigin=\"anonymous\" data-ratio=\"0.255\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOo4DlrLBiahBqBMZKteu40uSjKwS3EoENVvtglDibF48GPYxibsywlEEcGA\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4ece\u9876\u81f3\u5e95\uff0c\u73b0\u4ee3\u8ba1\u7b97\u673a\u91cc\u7684\u5b58\u50a8\u5668\u7c7b\u578b\u5206\u522b\u6709\uff1a\u5bc4\u5b58\u5668\u3001\u9ad8\u901f\u7f13\u5b58\u3001\u4e3b\u5b58\u548c\u78c1\u76d8\uff0c\u8fd9\u4e9b\u5b58\u50a8\u5668\u7684\u901f\u5ea6\u9010\u7ea7\u9012\u51cf\u800c\u5bb9\u91cf\u9010\u7ea7\u9012\u589e\u3002\u5b58\u53d6\u901f\u5ea6\u6700\u5feb\u7684\u662f\u5bc4\u5b58\u5668\uff0c\u56e0\u4e3a\u5bc4\u5b58\u5668\u7684\u5236\u4f5c\u6750\u6599\u548c CPU \u662f\u76f8\u540c\u7684\uff0c\u6240\u4ee5\u901f\u5ea6\u548c CPU \u4e00\u6837\u5feb\uff0cCPU 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\u5219\u6839\u636e\u4e0d\u540c\u7684\u67b6\u6784\u8bbe\u8ba1\u4f1a\u88ab\u8bbe\u8ba1\u6210\u72ec\u4eab\u6216\u8005\u5171\u4eab\u4e24\u79cd\u6a21\u5f0f\u4e4b\u4e00\uff0c\u6bd4\u5982 Intel \u7684\u591a\u6838\u82af\u7247\u91c7\u7528\u7684\u662f\u5171\u4eab L2 \u6a21\u5f0f\u800c AMD \u7684\u591a\u6838\u82af\u7247\u5219\u91c7\u7528\u7684\u662f\u72ec\u4eab L2 \u6a21\u5f0f\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7b2c\u4e09\u5c42\u5219\u662f\u4e3b\u5b58\uff0c\u4e5f\u5373\u4e3b\u5185\u5b58\uff0c\u901a\u5e38\u79f0\u4f5c\u968f\u673a\u8bbf\u95ee\u5b58\u50a8\u5668\uff08Random Access Memory, RAM\uff09\u3002\u662f\u4e0e CPU \u76f4\u63a5\u4ea4\u6362\u6570\u636e\u7684\u5185\u90e8\u5b58\u50a8\u5668\u3002\u5b83\u53ef\u4ee5\u968f\u65f6\u8bfb\u5199\uff08\u5237\u65b0\u65f6\u9664\u5916\uff09\uff0c\u800c\u4e14\u901f\u5ea6\u5f88\u5feb\uff0c\u901a\u5e38\u4f5c\u4e3a\u64cd\u4f5c\u7cfb\u7edf\u6216\u5176\u4ed6\u6b63\u5728\u8fd0\u884c\u4e2d\u7684\u7a0b\u5e8f\u7684\u4e34\u65f6\u8d44\u6599\u5b58\u50a8\u4ecb\u8d28\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6700\u540e\u5219\u662f\u78c1\u76d8\uff0c\u78c1\u76d8\u548c\u4e3b\u5b58\u76f8\u6bd4\uff0c\u6bcf\u4e2a\u4e8c\u8fdb\u5236\u4f4d\u7684\u6210\u672c\u4f4e\u4e86\u4e24\u4e2a\u6570\u91cf\u7ea7\uff0c\u56e0\u6b64\u5bb9\u91cf\u6bd4\u4e4b\u4f1a\u5927\u5f97\u591a\uff0c\u52a8\u8f84\u4e0a GB\u3001TB\uff0c\u800c\u95ee\u9898\u662f\u8bbf\u95ee\u901f\u5ea6\u5219\u6bd4\u4e3b\u5b58\u6162\u4e86\u5927\u6982\u4e09\u4e2a\u6570\u91cf\u7ea7\u3002\u673a\u68b0\u786c\u76d8\u901f\u5ea6\u6162\u4e3b\u8981\u662f\u56e0\u4e3a\u673a\u68b0\u81c2\u9700\u8981\u4e0d\u65ad\u5728\u91d1\u5c5e\u76d8\u7247\u4e4b\u95f4\u79fb\u52a8\uff0c\u7b49\u5f85\u78c1\u76d8\u6247\u533a\u65cb\u8f6c\u81f3\u78c1\u5934\u4e4b\u4e0b\uff0c\u7136\u540e\u624d\u80fd\u8fdb\u884c\u8bfb\u5199\u64cd\u4f5c\uff0c\u56e0\u6b64\u6548\u7387\u5f88\u4f4e\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><strong>\u4e3b\u5185\u5b58\u662f\u64cd\u4f5c\u7cfb\u7edf\u8fdb\u884c I\/O \u64cd\u4f5c\u7684\u91cd\u4e2d\u4e4b\u91cd\uff0c\u7edd\u5927\u90e8\u5206\u7684\u5de5\u4f5c\u90fd\u662f\u5728\u7528\u6237\u8fdb\u7a0b\u548c\u5185\u6838\u7684\u5185\u5b58\u7f13\u51b2\u533a\u91cc\u5b8c\u6210\u7684\uff0c\u56e0\u6b64\u6211\u4eec\u63a5\u4e0b\u6765\u9700\u8981\u63d0\u524d\u5b66\u4e60\u4e00\u4e9b\u4e3b\u5b58\u7684\u76f8\u5173\u539f\u7406\u3002<\/strong><\/p>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7269\u7406\u5185\u5b58<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6211\u4eec\u5e73\u65f6\u4e00\u76f4\u63d0\u53ca\u7684\u7269\u7406\u5185\u5b58\u5c31\u662f\u4e0a\u6587\u4e2d\u5bf9\u5e94\u7684\u7b2c\u4e09\u79cd\u8ba1\u7b97\u673a\u5b58\u50a8\u5668\uff0cRAM \u4e3b\u5b58\uff0c\u5b83\u5728\u8ba1\u7b97\u673a\u4e2d\u4ee5\u5185\u5b58\u6761\u7684\u5f62\u5f0f\u5b58\u5728\uff0c\u5d4c\u5728\u4e3b\u677f\u7684\u5185\u5b58\u69fd\u4e0a\uff0c\u7528\u6765\u52a0\u8f7d\u5404\u5f0f\u5404\u6837\u7684\u7a0b\u5e8f\u4e0e\u6570\u636e\u4ee5\u4f9b CPU \u76f4\u63a5\u8fd0\u884c\u548c\u4f7f\u7528\u3002<\/p>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u865a\u62df\u5185\u5b58<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5728\u8ba1\u7b97\u673a\u9886\u57df\u6709\u4e00\u53e5\u5982\u540c\u6469\u897f\u5341\u8beb\u822c\u795e\u5723\u7684\u54f2\u8a00\uff1a&#8221;<strong>\u8ba1\u7b97\u673a\u79d1\u5b66\u9886\u57df\u7684\u4efb\u4f55\u95ee\u9898\u90fd\u53ef\u4ee5\u901a\u8fc7\u589e\u52a0\u4e00\u4e2a\u95f4\u63a5\u7684\u4e2d\u95f4\u5c42\u6765\u89e3\u51b3<\/strong>&#8220;\uff0c\u4ece\u5185\u5b58\u7ba1\u7406\u3001\u7f51\u7edc\u6a21\u578b\u3001\u5e76\u53d1\u8c03\u5ea6\u751a\u81f3\u662f\u786c\u4ef6\u67b6\u6784\uff0c\u90fd\u80fd\u770b\u5230\u8fd9\u53e5\u54f2\u8a00\u5728\u95ea\u70c1\u7740\u5149\u8292\uff0c\u800c\u865a\u62df\u5185\u5b58\u5219\u662f\u8fd9\u4e00\u54f2\u8a00\u7684\u5b8c\u7f8e\u5b9e\u8df5\u4e4b\u4e00\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u865a\u62df\u5185\u5b58\u662f\u73b0\u4ee3\u8ba1\u7b97\u673a\u4e2d\u7684\u4e00\u4e2a\u975e\u5e38\u91cd\u8981\u7684\u5b58\u50a8\u5668\u62bd\u8c61\uff0c\u4e3b\u8981\u662f\u7528\u6765\u89e3\u51b3\u5e94\u7528\u7a0b\u5e8f\u65e5\u76ca\u589e\u957f\u7684\u5185\u5b58\u4f7f\u7528\u9700\u6c42\uff1a\u73b0\u4ee3\u7269\u7406\u5185\u5b58\u7684\u5bb9\u91cf\u589e\u957f\u5df2\u7ecf\u975e\u5e38\u5feb\u901f\u4e86\uff0c\u7136\u800c\u8fd8\u662f\u8ddf\u4e0d\u4e0a\u5e94\u7528\u7a0b\u5e8f\u5bf9\u4e3b\u5b58\u9700\u6c42\u7684\u589e\u957f\u901f\u5ea6\uff0c\u5bf9\u4e8e\u5e94\u7528\u7a0b\u5e8f\u6765\u8bf4\u5185\u5b58\u8fd8\u662f\u4e0d\u591f\u7528\uff0c\u56e0\u6b64\u4fbf\u9700\u8981\u4e00\u79cd\u65b9\u6cd5\u6765\u89e3\u51b3\u8fd9\u4e24\u8005\u4e4b\u95f4\u7684\u5bb9\u91cf\u5dee\u77db\u76fe\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8ba1\u7b97\u673a\u5bf9\u591a\u7a0b\u5e8f\u5185\u5b58\u8bbf\u95ee\u7684\u7ba1\u7406\u7ecf\u5386\u4e86\u00a0<code>\u9759\u6001\u91cd\u5b9a\u4f4d<\/code>\u00a0&#8211;&gt;\u00a0<code>\u52a8\u6001\u91cd\u5b9a\u4f4d<\/code>\u00a0&#8211;&gt;\u00a0<code>\u4ea4\u6362(swapping)\u6280\u672f<\/code>\u00a0&#8211;&gt;\u00a0<code>\u865a\u62df\u5185\u5b58<\/code>\uff0c\u6700\u539f\u59cb\u7684\u591a\u7a0b\u5e8f\u5185\u5b58\u8bbf\u95ee\u662f\u76f4\u63a5\u8bbf\u95ee\u7edd\u5bf9\u5185\u5b58\u5730\u5740\uff0c\u8fd9\u79cd\u65b9\u5f0f\u51e0\u4e4e\u662f\u5b8c\u5168\u4e0d\u53ef\u7528\u7684\u65b9\u6848\uff0c\u56e0\u4e3a\u5982\u679c\u6bcf\u4e00\u4e2a\u7a0b\u5e8f\u90fd\u76f4\u63a5\u8bbf\u95ee\u7269\u7406\u5185\u5b58\u5730\u5740\u7684\u8bdd\uff0c\u6bd4\u5982\u4e24\u4e2a\u7a0b\u5e8f\u5e76\u53d1\u6267\u884c\u4ee5\u4e0b\u6307\u4ee4\u7684\u65f6\u5019\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>mov cx, 2\r\nmov bx, 1000H\r\nmov ds, bx\r\nmov [0], cx\r\n\r\n...\r\n\r\nmov ax, [0]\r\nadd ax, ax\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u4e00\u6bb5\u6c47\u7f16\u8868\u793a\u5728\u5730\u5740 1000:0 \u5904\u5b58\u5165\u6570\u503c 2\uff0c\u7136\u540e\u5728\u540e\u9762\u7684\u903b\u8f91\u4e2d\u628a\u8be5\u5730\u5740\u7684\u503c\u53d6\u51fa\u6765\u4e58\u4ee5 2\uff0c\u6700\u7ec8\u5b58\u5165 ax \u5bc4\u5b58\u5668\u7684\u503c\u5c31\u662f 4\uff0c\u5982\u679c\u7b2c\u4e8c\u4e2a\u7a0b\u5e8f\u5b58\u5165 cx \u5bc4\u5b58\u5668\u91cc\u7684\u503c\u662f 3\uff0c\u90a3\u4e48\u5e76\u53d1\u6267\u884c\u7684\u65f6\u5019\uff0c\u7b2c\u4e00\u4e2a\u7a0b\u5e8f\u6700\u7ec8\u4ece ax \u5bc4\u5b58\u5668\u91cc\u5f97\u5230\u7684\u503c\u5c31\u53ef\u80fd\u662f 6\uff0c\u8fd9\u5c31\u5b8c\u5168\u9519\u8bef\u4e86\uff0c\u5f97\u5230\u810f\u6570\u636e\u8fd8\u9876\u591a\u7b97\u7a0b\u5e8f\u7ed3\u679c\u9519\u8bef\uff0c\u8981\u662f\u5176\u4ed6\u7a0b\u5e8f\u5f80\u7279\u5b9a\u7684\u5730\u5740\u91cc\u5199\u5165\u4e00\u4e9b\u5371\u9669\u7684\u6307\u4ee4\u800c\u88ab\u53e6\u4e00\u4e2a\u7a0b\u5e8f\u53d6\u51fa\u6765\u6267\u884c\uff0c\u8fd8\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6574\u4e2a\u7cfb\u7edf\u7684\u5d29\u6e83\u3002\u6240\u4ee5\uff0c\u4e3a\u4e86\u786e\u4fdd\u8fdb\u7a0b\u95f4\u4e92\u4e0d\u5e72\u6270\uff0c\u6bcf\u4e00\u4e2a\u7528\u6237\u8fdb\u7a0b\u90fd\u9700\u8981\u5b9e\u65f6\u77e5\u6653\u5f53\u524d\u5176\u4ed6\u8fdb\u7a0b\u5728\u4f7f\u7528\u54ea\u4e9b\u5185\u5b58\u5730\u5740\uff0c\u8fd9\u5bf9\u4e8e\u5199\u7a0b\u5e8f\u7684\u4eba\u6765\u8bf4\u65e0\u7591\u662f\u4e00\u573a\u5669\u68a6\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u56e0\u6b64\uff0c\u64cd\u4f5c\u7edd\u5bf9\u5185\u5b58\u5730\u5740\u662f\u5b8c\u5168\u4e0d\u53ef\u884c\u7684\u65b9\u6848\uff0c\u90a3\u5c31\u53ea\u80fd\u7528\u64cd\u4f5c\u76f8\u5bf9\u5185\u5b58\u5730\u5740\uff0c\u6211\u4eec\u77e5\u9053\u6bcf\u4e2a\u8fdb\u7a0b\u90fd\u4f1a\u6709\u81ea\u5df1\u7684\u8fdb\u7a0b\u5730\u5740\uff0c\u4ece 0 \u5f00\u59cb\uff0c\u53ef\u4ee5\u901a\u8fc7\u76f8\u5bf9\u5730\u5740\u6765\u8bbf\u95ee\u5185\u5b58\uff0c\u4f46\u662f\u8fd9\u540c\u6837\u6709\u95ee\u9898\uff0c\u8fd8\u662f\u524d\u9762\u7c7b\u4f3c\u7684\u95ee\u9898\uff0c\u6bd4\u5982\u6709\u4e24\u4e2a\u5927\u5c0f\u4e3a 16KB \u7684\u7a0b\u5e8f A \u548c B\uff0c\u73b0\u5728\u5b83\u4eec\u90fd\u88ab\u52a0\u8f7d\u8fdb\u4e86\u5185\u5b58\uff0c\u5185\u5b58\u5730\u5740\u6bb5\u5206\u522b\u662f 0 ~ 16384\uff0c16384 ~ 32768\u3002A \u7684\u7b2c\u4e00\u6761\u6307\u4ee4\u662f\u00a0<code>jmp 1024<\/code>\uff0c\u800c\u5728\u5730\u5740 1024 \u5904\u662f\u4e00\u6761\u00a0<code>mov<\/code>\u00a0\u6307\u4ee4\uff0c\u4e0b\u4e00\u6761\u6307\u4ee4\u662f\u00a0<code>add<\/code>\uff0c\u57fa\u4e8e\u524d\u9762\u7684\u00a0<code>mov<\/code>\u00a0\u6307\u4ee4\u505a\u52a0\u6cd5\u8fd0\u7b97\uff0c\u4e0e\u6b64\u540c\u65f6\uff0cB \u7684\u7b2c\u4e00\u6761\u6307\u4ee4\u662f\u00a0<code>jmp 1028<\/code>\uff0c\u672c\u6765\u5728 B \u7684\u76f8\u5bf9\u5730\u5740 1028 \u5904\u5e94\u8be5\u4e5f\u662f\u4e00\u6761\u00a0<code>mov<\/code>\u00a0\u53bb\u64cd\u4f5c\u81ea\u5df1\u7684\u5185\u5b58\u5730\u5740\u4e0a\u7684\u503c\uff0c\u4f46\u662f\u7531\u4e8e\u8fd9\u4e24\u4e2a\u7a0b\u5e8f\u5171\u4eab\u4e86\u6bb5\u5bc4\u5b58\u5668\uff0c\u56e0\u6b64\u867d\u7136\u4ed6\u4eec\u4f7f\u7528\u4e86\u5404\u81ea\u7684\u76f8\u5bf9\u5730\u5740\uff0c\u4f46\u662f\u4f9d\u7136\u64cd\u4f5c\u7684\u8fd8\u662f\u7edd\u5bf9\u5185\u5b58\u5730\u5740\uff0c\u4e8e\u662f B \u5c31\u4f1a\u8df3\u53bb\u6267\u884c\u00a0<code>add<\/code>\u00a0\u6307\u4ee4\uff0c\u8fd9\u65f6\u5019\u5c31\u4f1a\u56e0\u4e3a\u975e\u6cd5\u7684\u5185\u5b58\u64cd\u4f5c\u800c crash\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6709\u4e00\u79cd<code>\u9759\u6001\u91cd\u5b9a\u4f4d<\/code>\u7684\u6280\u672f\u53ef\u4ee5\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u5b83\u7684\u5de5\u4f5c\u539f\u7406\u975e\u5e38\u7b80\u5355\u7c97\u66b4\uff1a\u5f53 B \u7a0b\u5e8f\u88ab\u52a0\u8f7d\u5230\u5730\u5740 16384 \u5904\u4e4b\u540e\uff0c\u628a B \u7684\u6240\u6709\u76f8\u5bf9\u5185\u5b58\u5730\u5740\u90fd\u52a0\u4e0a 16384\uff0c\u8fd9\u6837\u7684\u8bdd\u5f53 B \u6267\u884c\u00a0<code>jmp 1028<\/code>\u00a0\u4e4b\u65f6\uff0c\u5176\u5b9e\u6267\u884c\u7684\u662f\u00a0<code>jmp 1028+16384<\/code>\uff0c\u5c31\u53ef\u4ee5\u8df3\u8f6c\u5230\u6b63\u786e\u7684\u5185\u5b58\u5730\u5740\u5904\u53bb\u6267\u884c\u6b63\u786e\u7684\u6307\u4ee4\u4e86\uff0c\u4f46\u662f\u8fd9\u79cd\u6280\u672f\u5e76\u4e0d\u901a\u7528\uff0c\u800c\u4e14\u8fd8\u4f1a\u5bf9\u7a0b\u5e8f\u88c5\u8f7d\u8fdb\u5185\u5b58\u7684\u6027\u80fd\u6709\u5f71\u54cd\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u518d\u5f80\u540e\uff0c\u5c31\u53d1\u5c55\u51fa\u6765\u4e86\u5b58\u50a8\u5668\u62bd\u8c61\uff1a\u5730\u5740\u7a7a\u95f4\uff0c\u5c31\u597d\u50cf\u8fdb\u7a0b\u662f CPU \u7684\u62bd\u8c61\uff0c\u5730\u5740\u7a7a\u95f4\u5219\u662f\u5b58\u50a8\u5668\u7684\u62bd\u8c61\uff0c\u6bcf\u4e2a\u8fdb\u7a0b\u90fd\u4f1a\u5206\u914d\u72ec\u4eab\u7684\u5730\u5740\u7a7a\u95f4\uff0c\u4f46\u662f\u72ec\u4eab\u7684\u5730\u5740\u7a7a\u95f4\u53c8\u5e26\u6765\u4e86\u65b0\u7684\u95ee\u9898\uff1a\u5982\u4f55\u5b9e\u73b0\u4e0d\u540c\u8fdb\u7a0b\u7684\u76f8\u540c\u76f8\u5bf9\u5730\u5740\u6307\u5411\u4e0d\u540c\u7684\u7269\u7406\u5730\u5740\uff1f\u6700\u5f00\u59cb\u662f\u4f7f\u7528<code>\u52a8\u6001\u91cd\u5b9a\u4f4d<\/code>\u6280\u672f\u6765\u5b9e\u73b0\uff0c\u8fd9\u662f\u7528\u4e00\u79cd\u76f8\u5bf9\u7b80\u5355\u7684\u5730\u5740\u7a7a\u95f4\u5230\u7269\u7406\u5185\u5b58\u7684\u6620\u5c04\u65b9\u6cd5\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u57fa\u672c\u539f\u7406\u5c31\u662f\u4e3a\u6bcf\u4e00\u4e2a CPU \u914d\u5907\u4e24\u4e2a\u7279\u6b8a\u7684\u786c\u4ef6\u5bc4\u5b58\u5668\uff1a\u57fa\u5740\u5bc4\u5b58\u5668\u548c\u754c\u9650\u5bc4\u5b58\u5668\uff0c\u7528\u6765\u52a8\u6001\u4fdd\u5b58\u6bcf\u4e00\u4e2a\u7a0b\u5e8f\u7684\u8d77\u59cb\u7269\u7406\u5185\u5b58\u5730\u5740\u548c\u957f\u5ea6\uff0c\u6bd4\u5982\u524d\u6587\u4e2d\u7684 A\uff0cB \u4e24\u4e2a\u7a0b\u5e8f\uff0c\u5f53 A \u8fd0\u884c\u65f6\u57fa\u5740\u5bc4\u5b58\u5668\u548c\u754c\u9650\u5bc4\u5b58\u5668\u5c31\u4f1a\u5206\u522b\u5b58\u5165 0 \u548c 16384\uff0c\u800c\u5f53 B \u8fd0\u884c\u65f6\u5219\u4e24\u4e2a\u5bc4\u5b58\u5668\u53c8\u4f1a\u5206\u522b\u5b58\u5165 16384 \u548c 32768\u3002\u7136\u540e\u6bcf\u6b21\u8bbf\u95ee\u6307\u5b9a\u7684\u5185\u5b58\u5730\u5740\u65f6\uff0cCPU \u4f1a\u5728\u628a\u5730\u5740\u53d1\u5f80\u5185\u5b58\u603b\u7ebf\u4e4b\u524d\u81ea\u52a8\u628a\u57fa\u5740\u5bc4\u5b58\u5668\u91cc\u7684\u503c\u52a0\u5230\u8be5\u5185\u5b58\u5730\u5740\u4e0a\uff0c\u5f97\u5230\u4e00\u4e2a\u771f\u6b63\u7684\u7269\u7406\u5185\u5b58\u5730\u5740\uff0c\u540c\u65f6\u8fd8\u4f1a\u6839\u636e\u754c\u9650\u5bc4\u5b58\u5668\u91cc\u7684\u503c\u68c0\u67e5\u8be5\u5730\u5740\u662f\u5426\u6ea2\u51fa\uff0c\u82e5\u662f\uff0c\u5219\u4ea7\u751f\u9519\u8bef\u4e2d\u6b62\u7a0b\u5e8f\uff0c<code>\u52a8\u6001\u91cd\u5b9a\u4f4d<\/code>\u6280\u672f\u89e3\u51b3\u4e86<code>\u9759\u6001\u91cd\u5b9a\u4f4d<\/code>\u6280\u672f\u9020\u6210\u7684\u7a0b\u5e8f\u88c5\u8f7d\u901f\u5ea6\u6162\u7684\u95ee\u9898\uff0c\u4f46\u662f\u4e5f\u6709\u65b0\u95ee\u9898\uff1a\u6bcf\u6b21\u8bbf\u95ee\u5185\u5b58\u90fd\u9700\u8981\u8fdb\u884c\u52a0\u6cd5\u548c\u6bd4\u8f83\u8fd0\u7b97\uff0c\u6bd4\u8f83\u8fd0\u7b97\u672c\u8eab\u53ef\u4ee5\u5f88\u5feb\uff0c\u4f46\u662f\u52a0\u6cd5\u8fd0\u7b97\u7531\u4e8e\u8fdb\u4f4d\u4f20\u9012\u65f6\u95f4\u7684\u95ee\u9898\uff0c\u9664\u975e\u4f7f\u7528\u7279\u6b8a\u7684\u7535\u8def\uff0c\u5426\u5219\u4f1a\u6bd4\u8f83\u6162\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7136\u540e\u5c31\u662f\u00a0<code>\u4ea4\u6362\uff08swapping\uff09<\/code>\u6280\u672f\uff0c\u8fd9\u79cd\u6280\u672f\u7b80\u5355\u6765\u8bf4\u5c31\u662f\u52a8\u6001\u5730\u628a\u7a0b\u5e8f\u5728\u5185\u5b58\u548c\u78c1\u76d8\u4e4b\u95f4\u8fdb\u884c\u4ea4\u6362\u4fdd\u5b58\uff0c\u8981\u8fd0\u884c\u4e00\u4e2a\u8fdb\u7a0b\u7684\u65f6\u5019\u5c31\u628a\u7a0b\u5e8f\u7684\u4ee3\u7801\u6bb5\u548c\u6570\u636e\u6bb5\u8c03\u5165\u5185\u5b58\uff0c\u7136\u540e\u518d\u628a\u7a0b\u5e8f\u5c01\u5b58\uff0c\u5b58\u5165\u78c1\u76d8\uff0c\u5982\u6b64\u53cd\u590d\u3002\u4e3a\u4ec0\u4e48\u8981\u8fd9\u4e48\u9ebb\u70e6\uff1f\u56e0\u4e3a\u524d\u9762\u90a3\u4e24\u79cd\u91cd\u5b9a\u4f4d\u6280\u672f\u7684\u524d\u63d0\u6761\u4ef6\u662f\u8ba1\u7b97\u673a\u5185\u5b58\u8db3\u591f\u5927\uff0c\u80fd\u591f\u628a\u6240\u6709\u8981\u8fd0\u884c\u7684\u8fdb\u7a0b\u5730\u5740\u7a7a\u95f4\u90fd\u52a0\u8f7d\u8fdb\u4e3b\u5b58\uff0c\u624d\u80fd\u591f\u5e76\u53d1\u8fd0\u884c\u8fd9\u4e9b\u8fdb\u7a0b\uff0c\u4f46\u662f\u73b0\u5b9e\u5f80\u5f80\u4e0d\u662f\u5982\u6b64\uff0c\u5185\u5b58\u7684\u5927\u5c0f\u603b\u662f\u6709\u9650\u7684\uff0c\u6240\u6709\u5c31\u9700\u8981\u53e6\u4e00\u7c7b\u65b9\u6cd5\u6765\u5904\u7406\u5185\u5b58\u8d85\u8f7d\u7684\u60c5\u51b5\uff0c\u7b2c\u4e00\u79cd\u4fbf\u662f\u7b80\u5355\u7684\u4ea4\u6362\u6280\u672f\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOochzfD7emQyIdd88nofTY9udj9LL43kcmhHXyU8pdOSbb3FwnIHLSWw\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.44689655172413795\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOochzfD7emQyIdd88nofTY9udj9LL43kcmhHXyU8pdOSbb3FwnIHLSWw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1450\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5148\u628a\u8fdb\u7a0b A \u6362\u5165\u5185\u5b58\uff0c\u7136\u540e\u542f\u52a8\u8fdb\u7a0b B \u548c C\uff0c\u4e5f\u6362\u5165\u5185\u5b58\uff0c\u63a5\u7740 A \u88ab\u4ece\u5185\u5b58\u4ea4\u6362\u5230\u78c1\u76d8\uff0c\u7136\u540e\u53c8\u6709\u65b0\u7684\u8fdb\u7a0b D \u8c03\u5165\u5185\u5b58\uff0c\u7528\u4e86 A 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data-tool=\"mdnice\u7f16\u8f91\u5668\">\u53e6\u4e00\u79cd\u5904\u7406\u5185\u5b58\u8d85\u8f7d\u7684\u6280\u672f\u5c31\u662f<code>\u865a\u62df\u5185\u5b58<\/code>\u6280\u672f\u4e86\uff0c\u5b83\u6bd4<code>\u4ea4\u6362\uff08swapping\uff09<\/code>\u6280\u672f\u66f4\u590d\u6742\u800c\u53c8\u66f4\u9ad8\u6548\uff0c\u662f\u76ee\u524d\u6700\u65b0\u5e94\u7528\u6700\u5e7f\u6cdb\u7684\u5b58\u50a8\u5668\u62bd\u8c61\u6280\u672f\uff1a<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u865a\u62df\u5185\u5b58\u7684\u6838\u5fc3\u539f\u7406\u662f\uff1a\u4e3a\u6bcf\u4e2a\u7a0b\u5e8f\u8bbe\u7f6e\u4e00\u6bb5&#8221;\u8fde\u7eed&#8221;\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f4\uff0c\u628a\u8fd9\u4e2a\u5730\u5740\u7a7a\u95f4\u5206\u5272\u6210\u591a\u4e2a\u5177\u6709\u8fde\u7eed\u5730\u5740\u8303\u56f4\u7684\u9875 (page)\uff0c\u5e76\u628a\u8fd9\u4e9b\u9875\u548c\u7269\u7406\u5185\u5b58\u505a\u6620\u5c04\uff0c\u5728\u7a0b\u5e8f\u8fd0\u884c\u671f\u95f4\u52a8\u6001\u6620\u5c04\u5230\u7269\u7406\u5185\u5b58\u3002\u5f53\u7a0b\u5e8f\u5f15\u7528\u5230\u4e00\u6bb5\u5728\u7269\u7406\u5185\u5b58\u7684\u5730\u5740\u7a7a\u95f4\u65f6\uff0c\u7531\u786c\u4ef6\u7acb\u523b\u6267\u884c\u5fc5\u8981\u7684\u6620\u5c04\uff1b\u800c\u5f53\u7a0b\u5e8f\u5f15\u7528\u5230\u4e00\u6bb5\u4e0d\u5728\u7269\u7406\u5185\u5b58\u4e2d\u7684\u5730\u5740\u7a7a\u95f4\u65f6\uff0c\u7531\u64cd\u4f5c\u7cfb\u7edf\u8d1f\u8d23\u5c06\u7f3a\u5931\u7684\u90e8\u5206\u88c5\u5165\u7269\u7406\u5185\u5b58\u5e76\u91cd\u65b0\u6267\u884c\u5931\u8d25\u7684\u6307\u4ee4\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoK9OLKEPlRBzTD8ZmS6w4GIEw6hVaqLCv9pokicyKl0l2o2o0JcOSKNA\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"1.2367256637168142\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoK9OLKEPlRBzTD8ZmS6w4GIEw6hVaqLCv9pokicyKl0l2o2o0JcOSKNA\/640?wx_fmt=png\" data-type=\"png\" data-w=\"904\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u865a\u62df\u5730\u5740\u7a7a\u95f4\u6309\u7167\u56fa\u5b9a\u5927\u5c0f\u5212\u5206\u6210\u88ab\u79f0\u4e3a\u9875\uff08page\uff09\u7684\u82e5\u5e72\u5355\u5143\uff0c\u7269\u7406\u5185\u5b58\u4e2d\u5bf9\u5e94\u7684\u5219\u662f\u9875\u6846\uff08page frame\uff09\u3002\u8fd9\u4e24\u8005\u4e00\u822c\u6765\u8bf4\u662f\u4e00\u6837\u7684\u5927\u5c0f\uff0c\u5982\u4e0a\u56fe\u4e2d\u7684\u662f 4KB\uff0c\u4e0d\u8fc7\u5b9e\u9645\u4e0a\u8ba1\u7b97\u673a\u7cfb\u7edf\u4e2d\u4e00\u822c\u662f 512 \u5b57\u8282\u5230 1 GB\uff0c\u8fd9\u5c31\u662f\u865a\u62df\u5185\u5b58\u7684\u5206\u9875\u6280\u672f\u3002\u56e0\u4e3a\u662f\u865a\u62df\u5185\u5b58\u7a7a\u95f4\uff0c\u6bcf\u4e2a\u8fdb\u7a0b\u5206\u914d\u7684\u5927\u5c0f\u662f 4GB (32 \u4f4d\u67b6\u6784)\uff0c\u800c\u5b9e\u9645\u4e0a\u5f53\u7136\u4e0d\u53ef\u80fd\u7ed9\u6240\u6709\u5728\u8fd0\u884c\u4e2d\u7684\u8fdb\u7a0b\u90fd\u5206\u914d 4GB \u7684\u7269\u7406\u5185\u5b58\uff0c\u6240\u4ee5\u865a\u62df\u5185\u5b58\u6280\u672f\u8fd8\u9700\u8981\u5229\u7528\u5230\u524d\u9762\u4ecb\u7ecd\u7684<code>\u4ea4\u6362\uff08swapping\uff09<\/code>\u6280\u672f\uff0c\u5728\u8fdb\u7a0b\u8fd0\u884c\u671f\u95f4\u53ea\u5206\u914d\u6620\u5c04\u5f53\u524d\u4f7f\u7528\u5230\u7684\u5185\u5b58\uff0c\u6682\u65f6\u4e0d\u4f7f\u7528\u7684\u6570\u636e\u5219\u5199\u56de\u78c1\u76d8\u4f5c\u4e3a\u526f\u672c\u4fdd\u5b58\uff0c\u9700\u8981\u7528\u7684\u65f6\u5019\u518d\u8bfb\u5165\u5185\u5b58\uff0c\u52a8\u6001\u5730\u5728\u78c1\u76d8\u548c\u5185\u5b58\u4e4b\u95f4\u4ea4\u6362\u6570\u636e\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5176\u5b9e\u865a\u62df\u5185\u5b58\u6280\u672f\u4ece\u67d0\u79cd\u89d2\u5ea6\u6765\u770b\u7684\u8bdd\uff0c\u5f88\u50cf\u662f\u7cc5\u5408\u4e86\u57fa\u5740\u5bc4\u5b58\u5668\u548c\u754c\u9650\u5bc4\u5b58\u5668\u4e4b\u540e\u7684\u65b0\u6280\u672f\u3002\u5b83\u4f7f\u5f97\u6574\u4e2a\u8fdb\u7a0b\u7684\u5730\u5740\u7a7a\u95f4\u53ef\u4ee5\u901a\u8fc7\u8f83\u5c0f\u7684\u5355\u5143\u6620\u5c04\u5230\u7269\u7406\u5185\u5b58\uff0c\u800c\u4e0d\u9700\u8981\u4e3a\u7a0b\u5e8f\u7684\u4ee3\u7801\u548c\u6570\u636e\u5730\u5740\u8fdb\u884c\u91cd\u5b9a\u4f4d\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fdb\u7a0b\u5728\u8fd0\u884c\u671f\u95f4\u4ea7\u751f\u7684\u5185\u5b58\u5730\u5740\u90fd\u662f\u865a\u62df\u5730\u5740\uff0c\u5982\u679c\u8ba1\u7b97\u673a\u6ca1\u6709\u5f15\u5165\u865a\u62df\u5185\u5b58\u8fd9\u79cd\u5b58\u50a8\u5668\u62bd\u8c61\u6280\u672f\u7684\u8bdd\uff0c\u5219 CPU \u4f1a\u628a\u8fd9\u4e9b\u5730\u5740\u76f4\u63a5\u53d1\u9001\u5230\u5185\u5b58\u5730\u5740\u603b\u7ebf\u4e0a\uff0c\u76f4\u63a5\u8bbf\u95ee\u548c\u865a\u62df\u5730\u5740\u76f8\u540c\u503c\u7684\u7269\u7406\u5730\u5740\uff1b\u5982\u679c\u4f7f\u7528\u865a\u62df\u5185\u5b58\u6280\u672f\u7684\u8bdd\uff0cCPU \u5219\u662f\u628a\u8fd9\u4e9b\u865a\u62df\u5730\u5740\u901a\u8fc7\u5730\u5740\u603b\u7ebf\u9001\u5230\u5185\u5b58\u7ba1\u7406\u5355\u5143\uff08Memory Management Unit\uff0cMMU\uff09\uff0cMMU \u5c06\u865a\u62df\u5730\u5740\u6620\u5c04\u4e3a\u7269\u7406\u5730\u5740\u4e4b\u540e\u518d\u901a\u8fc7\u5185\u5b58\u603b\u7ebf\u53bb\u8bbf\u95ee\u7269\u7406\u5185\u5b58\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"img_loading\" src=\"data:image\/gif;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQImWNgYGBgAAAABQABh6FO1AAAAABJRU5ErkJggg==\" crossorigin=\"anonymous\" data-ratio=\"0.41833333333333333\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoRLztMJS4RU9bg4JtQ2HY4KMXfqCz7FQJKWbFic5ibDGtvYe0vTiaMKtYw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u865a\u62df\u5730\u5740\uff08\u6bd4\u5982 16 \u4f4d\u5730\u5740 8196=0010 000000000100\uff09\u5206\u4e3a\u4e24\u90e8\u5206\uff1a\u865a\u62df\u9875\u53f7\uff08\u9ad8\u4f4d\u90e8\u5206\uff09\u548c\u504f\u79fb\u91cf\uff08\u4f4e\u4f4d\u90e8\u5206\uff09\uff0c\u865a\u62df\u5730\u5740\u8f6c\u6362\u6210\u7269\u7406\u5730\u5740\u662f\u901a\u8fc7\u9875\u8868\uff08page table\uff09\u6765\u5b9e\u73b0\u7684\uff0c\u9875\u8868\u7531\u9875\u8868\u9879\u6784\u6210\uff0c\u9875\u8868\u9879\u4e2d\u4fdd\u5b58\u4e86\u9875\u6846\u53f7\u3001\u4fee\u6539\u4f4d\u3001\u8bbf\u95ee\u4f4d\u3001\u4fdd\u62a4\u4f4d\u548c &#8220;\u5728\/\u4e0d\u5728&#8221; \u4f4d\u7b49\u4fe1\u606f\uff0c\u4ece\u6570\u5b66\u89d2\u5ea6\u6765\u8bf4\u9875\u8868\u5c31\u662f\u4e00\u4e2a\u51fd\u6570\uff0c\u5165\u53c2\u662f\u865a\u62df\u9875\u53f7\uff0c\u8f93\u51fa\u662f\u7269\u7406\u9875\u6846\u53f7\uff0c\u5f97\u5230\u7269\u7406\u9875\u6846\u53f7\u4e4b\u540e\u590d\u5236\u5230\u5bc4\u5b58\u5668\u7684\u9ad8\u4e09\u4f4d\u4e2d\uff0c\u6700\u540e\u76f4\u63a5\u628a 12 \u4f4d\u7684\u504f\u79fb\u91cf\u590d\u5236\u5230\u5bc4\u5b58\u5668\u7684\u672b 12 \u4f4d\u6784\u6210 15 \u4f4d\u7684\u7269\u7406\u5730\u5740\uff0c\u5373\u53ef\u4ee5\u628a\u8be5\u5bc4\u5b58\u5668\u7684\u5b58\u50a8\u7684\u7269\u7406\u5185\u5b58\u5730\u5740\u53d1\u9001\u5230\u5185\u5b58\u603b\u7ebf\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoibxmldI0NdU2hMh6dAiaCet7yPX1Seu4e3iaBAny6JBiaHLMLo11tBTKWw\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"1.2072243346007605\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoibxmldI0NdU2hMh6dAiaCet7yPX1Seu4e3iaBAny6JBiaHLMLo11tBTKWw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1052\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5728 MMU \u8fdb\u884c\u5730\u5740\u8f6c\u6362\u65f6\uff0c\u5982\u679c\u9875\u8868\u9879\u7684 &#8220;\u5728\/\u4e0d\u5728&#8221; \u4f4d\u662f 0\uff0c\u5219\u8868\u793a\u8be5\u9875\u9762\u5e76\u6ca1\u6709\u6620\u5c04\u5230\u771f\u5b9e\u7684\u7269\u7406\u9875\u6846\uff0c\u5219\u4f1a\u5f15\u53d1\u4e00\u4e2a<strong>\u7f3a\u9875\u4e2d\u65ad<\/strong>\uff0cCPU \u9677\u5165\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\uff0c\u63a5\u7740\u64cd\u4f5c\u7cfb\u7edf\u5c31\u4f1a\u901a\u8fc7\u9875\u9762\u7f6e\u6362\u7b97\u6cd5\u9009\u62e9\u4e00\u4e2a\u9875\u9762\u5c06\u5176\u6362\u51fa (swap)\uff0c\u4ee5\u4fbf\u4e3a\u5373\u5c06\u8c03\u5165\u7684\u65b0\u9875\u9762\u817e\u51fa\u4f4d\u7f6e\uff0c\u5982\u679c\u8981\u6362\u51fa\u7684\u9875\u9762\u7684\u9875\u8868\u9879\u91cc\u7684\u4fee\u6539\u4f4d\u5df2\u7ecf\u88ab\u8bbe\u7f6e\u8fc7\uff0c\u4e5f\u5c31\u662f\u88ab\u66f4\u65b0\u8fc7\uff0c\u5219\u8fd9\u662f\u4e00\u4e2a\u810f\u9875 (dirty page)\uff0c\u9700\u8981\u5199\u56de\u78c1\u76d8\u66f4\u65b0\u6539\u9875\u9762\u5728\u78c1\u76d8\u4e0a\u7684\u526f\u672c\uff0c\u5982\u679c\u8be5\u9875\u9762\u662f&#8221;\u5e72\u51c0&#8221;\u7684\uff0c\u4e5f\u5c31\u662f\u6ca1\u6709\u88ab\u4fee\u6539\u8fc7\uff0c\u5219\u76f4\u63a5\u7528\u8c03\u5165\u7684\u65b0\u9875\u9762\u8986\u76d6\u6389\u88ab\u6362\u51fa\u7684\u65e7\u9875\u9762\u5373\u53ef\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6700\u540e\uff0c\u8fd8\u9700\u8981\u4e86\u89e3\u7684\u4e00\u4e2a\u6982\u5ff5\u662f\u8f6c\u6362\u68c0\u6d4b\u7f13\u51b2\u5668\uff08Translation Lookaside Buffer\uff0cTLB\uff09\uff0c\u4e5f\u53eb\u5feb\u8868\uff0c\u662f\u7528\u6765\u52a0\u901f\u865a\u62df\u5730\u5740\u6620\u5c04\u7684\uff0c\u56e0\u4e3a\u865a\u62df\u5185\u5b58\u7684\u5206\u9875\u673a\u5236\uff0c\u9875\u8868\u4e00\u822c\u662f\u4fdd\u5b58\u5185\u5b58\u4e2d\u7684\u4e00\u5757\u56fa\u5b9a\u7684\u5b58\u50a8\u533a\uff0c\u5bfc\u81f4\u8fdb\u7a0b\u901a\u8fc7 MMU \u8bbf\u95ee\u5185\u5b58\u6bd4\u76f4\u63a5\u8bbf\u95ee\u5185\u5b58\u591a\u4e86\u4e00\u6b21\u5185\u5b58\u8bbf\u95ee\uff0c\u6027\u80fd\u81f3\u5c11\u4e0b\u964d\u4e00\u534a\uff0c\u56e0\u6b64\u9700\u8981\u5f15\u5165\u52a0\u901f\u673a\u5236\uff0c\u5373 TLB \u5feb\u8868\uff0cTLB \u53ef\u4ee5\u7b80\u5355\u5730\u7406\u89e3\u6210\u9875\u8868\u7684\u9ad8\u901f\u7f13\u5b58\uff0c\u4fdd\u5b58\u4e86\u6700\u9ad8\u9891\u88ab\u8bbf\u95ee\u7684\u9875\u8868\u9879\uff0c\u7531\u4e8e\u4e00\u822c\u662f\u786c\u4ef6\u5b9e\u73b0\u7684\uff0c\u56e0\u6b64\u901f\u5ea6\u6781\u5feb\uff0cMMU \u6536\u5230\u865a\u62df\u5730\u5740\u65f6\u4e00\u822c\u4f1a\u5148\u901a\u8fc7\u786c\u4ef6 TLB \u67e5\u8be2\u5bf9\u5e94\u7684\u9875\u8868\u53f7\uff0c\u82e5\u547d\u4e2d\u4e14\u8be5\u9875\u8868\u9879\u7684\u8bbf\u95ee\u64cd\u4f5c\u5408\u6cd5\uff0c\u5219\u76f4\u63a5\u4ece TLB \u53d6\u51fa\u5bf9\u5e94\u7684\u7269\u7406\u9875\u6846\u53f7\u8fd4\u56de\uff0c\u82e5\u4e0d\u547d\u4e2d\u5219\u7a7f\u900f\u5230\u5185\u5b58\u9875\u8868\u91cc\u67e5\u8be2\uff0c\u5e76\u4e14\u4f1a\u7528\u8fd9\u4e2a\u4ece\u5185\u5b58\u9875\u8868\u91cc\u67e5\u8be2\u5230\u6700\u65b0\u9875\u8868\u9879\u66ff\u6362\u5230\u73b0\u6709 TLB \u91cc\u7684\u5176\u4e2d\u4e00\u4e2a\uff0c\u4ee5\u5907\u4e0b\u6b21\u7f13\u5b58\u547d\u4e2d\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u81f3\u6b64\uff0c\u6211\u4eec\u4ecb\u7ecd\u5b8c\u4e86\u5305\u542b\u865a\u62df\u5185\u5b58\u5728\u5185\u7684\u591a\u9879\u8ba1\u7b97\u673a\u5b58\u50a8\u5668\u62bd\u8c61\u6280\u672f\uff0c\u865a\u62df\u5185\u5b58\u7684\u5176\u4ed6\u5185\u5bb9\u6bd4\u5982\u9488\u5bf9\u5927\u5185\u5b58\u7684\u591a\u7ea7\u9875\u8868\u3001\u5012\u6392\u9875\u8868\uff0c\u4ee5\u53ca\u5904\u7406\u7f3a\u9875\u4e2d\u65ad\u7684\u9875\u9762\u7f6e\u6362\u7b97\u6cd5\u7b49\u7b49\uff0c\u4ee5\u540e\u6709\u673a\u4f1a\u518d\u5355\u72ec\u5199\u4e00\u7bc7\u6587\u7ae0\u4ecb\u7ecd\uff0c\u6216\u8005\u5404\u4f4d\u8bfb\u8005\u4e5f\u53ef\u4ee5\u5148\u884c\u53bb\u67e5\u9605\u76f8\u5173\u8d44\u6599\u4e86\u89e3\uff0c\u8fd9\u91cc\u5c31\u4e0d\u518d\u6df1\u5165\u4e86\u3002<\/p>\n<h3 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7528\u6237\u6001\u548c\u5185\u6838\u6001<\/h3>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e00\u822c\u6765\u8bf4\uff0c\u6211\u4eec\u5728\u7f16\u5199\u7a0b\u5e8f\u64cd\u4f5c Linux I\/O \u4e4b\u65f6\u5341\u6709\u516b\u4e5d\u662f\u5728\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u4f20\u8f93\u6570\u636e\uff0c\u56e0\u6b64\u6709\u5fc5\u8981\u5148\u4e86\u89e3\u4e00\u4e0b Linux \u7684\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u6982\u5ff5\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u9996\u5148\u662f\u7528\u6237\u6001\u548c\u5185\u6838\u6001\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_jpg\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoDSWcdRjT5uzIGsulTfaGjvZ5nH6SfIrgp8yZ1qyxpVU8C4kFAicicjSA\/640?wx_fmt=jpeg&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.75\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_jpg\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoDSWcdRjT5uzIGsulTfaGjvZ5nH6SfIrgp8yZ1qyxpVU8C4kFAicicjSA\/640?wx_fmt=jpeg\" data-type=\"jpeg\" data-w=\"960\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4ece\u5b8f\u89c2\u4e0a\u6765\u770b\uff0cLinux \u64cd\u4f5c\u7cfb\u7edf\u7684\u4f53\u7cfb\u67b6\u6784\u5206\u4e3a\u7528\u6237\u6001\u548c\u5185\u6838\u6001\uff08\u6216\u8005\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\uff09\u3002\u5185\u6838\u4ece\u672c\u8d28\u4e0a\u770b\u662f\u4e00\u79cd\u8f6f\u4ef6 \u2014\u2014 \u63a7\u5236\u8ba1\u7b97\u673a\u7684\u786c\u4ef6\u8d44\u6e90\uff0c\u5e76\u63d0\u4f9b\u4e0a\u5c42\u5e94\u7528\u7a0b\u5e8f (\u8fdb\u7a0b) \u8fd0\u884c\u7684\u73af\u5883\u3002\u7528\u6237\u6001\u5373\u4e0a\u5c42\u5e94\u7528\u7a0b\u5e8f (\u8fdb\u7a0b) \u7684\u8fd0\u884c\u7a7a\u95f4\uff0c\u5e94\u7528\u7a0b\u5e8f (\u8fdb\u7a0b) \u7684\u6267\u884c\u5fc5\u987b\u4f9d\u6258\u4e8e\u5185\u6838\u63d0\u4f9b\u7684\u8d44\u6e90\uff0c\u8fd9\u5176\u4e2d\u5305\u62ec\u4f46\u4e0d\u9650\u4e8e CPU \u8d44\u6e90\u3001\u5b58\u50a8\u8d44\u6e90\u3001I\/O \u8d44\u6e90\u7b49\u7b49\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u73b0\u4ee3\u64cd\u4f5c\u7cfb\u7edf\u90fd\u662f\u91c7\u7528\u865a\u62df\u5b58\u50a8\u5668\uff0c\u90a3\u4e48\u5bf9 32 \u4f4d\u64cd\u4f5c\u7cfb\u7edf\u800c\u8a00\uff0c\u5b83\u7684\u5bfb\u5740\u7a7a\u95f4\uff08\u865a\u62df\u5b58\u50a8\u7a7a\u95f4\uff09\u4e3a 2^32 B = 4G\u3002\u64cd\u4f5c\u7cfb\u7edf\u7684\u6838\u5fc3\u662f\u5185\u6838\uff0c\u72ec\u7acb\u4e8e\u666e\u901a\u7684\u5e94\u7528\u7a0b\u5e8f\uff0c\u53ef\u4ee5\u8bbf\u95ee\u53d7\u4fdd\u62a4\u7684\u5185\u5b58\u7a7a\u95f4\uff0c\u4e5f\u6709\u8bbf\u95ee\u5e95\u5c42\u786c\u4ef6\u8bbe\u5907\u7684\u6240\u6709\u6743\u9650\u3002\u4e3a\u4e86\u4fdd\u8bc1\u7528\u6237\u8fdb\u7a0b\u4e0d\u80fd\u76f4\u63a5\u64cd\u4f5c\u5185\u6838\uff08kernel\uff09\uff0c\u4fdd\u8bc1\u5185\u6838\u7684\u5b89\u5168\uff0c\u64cd\u5fc3\u7cfb\u7edf\u5c06\u865a\u62df\u7a7a\u95f4\u5212\u5206\u4e3a\u4e24\u90e8\u5206\uff0c\u4e00\u90e8\u5206\u4e3a\u5185\u6838\u7a7a\u95f4\uff0c\u4e00\u90e8\u5206\u4e3a\u7528\u6237\u7a7a\u95f4\u3002\u9488\u5bf9 Linux \u64cd\u4f5c\u7cfb\u7edf\u800c\u8a00\uff0c\u5c06\u6700\u9ad8\u7684 1G \u5b57\u8282\uff08\u4ece\u865a\u62df\u5730\u5740 0xC0000000 \u5230 0xFFFFFFFF\uff09\uff0c\u4f9b\u5185\u6838\u4f7f\u7528\uff0c\u79f0\u4e3a\u5185\u6838\u7a7a\u95f4\uff0c\u800c\u5c06\u8f83\u4f4e\u7684 3G \u5b57\u8282\uff08\u4ece\u865a\u62df\u5730\u5740 0x00000000 \u5230 0xBFFFFFFF\uff09\uff0c\u4f9b\u5404\u4e2a\u8fdb\u7a0b\u4f7f\u7528\uff0c\u79f0\u4e3a\u7528\u6237\u7a7a\u95f4\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u56e0\u4e3a\u64cd\u4f5c\u7cfb\u7edf\u7684\u8d44\u6e90\u662f\u6709\u9650\u7684\uff0c\u5982\u679c\u8bbf\u95ee\u8d44\u6e90\u7684\u64cd\u4f5c\u8fc7\u591a\uff0c\u5fc5\u7136\u4f1a\u6d88\u8017\u8fc7\u591a\u7684\u7cfb\u7edf\u8d44\u6e90\uff0c\u800c\u4e14\u5982\u679c\u4e0d\u5bf9\u8fd9\u4e9b\u64cd\u4f5c\u52a0\u4ee5\u533a\u5206\uff0c\u5f88\u53ef\u80fd\u9020\u6210\u8d44\u6e90\u8bbf\u95ee\u7684\u51b2\u7a81\u3002\u6240\u4ee5\uff0c\u4e3a\u4e86\u51cf\u5c11\u6709\u9650\u8d44\u6e90\u7684\u8bbf\u95ee\u548c\u4f7f\u7528\u51b2\u7a81\uff0cUnix\/Linux \u7684\u8bbe\u8ba1\u54f2\u5b66\u4e4b\u4e00\u5c31\u662f\uff1a\u5bf9\u4e0d\u540c\u7684\u64cd\u4f5c\u8d4b\u4e88\u4e0d\u540c\u7684\u6267\u884c\u7b49\u7ea7\uff0c\u5c31\u662f\u6240\u8c13\u7279\u6743\u7684\u6982\u5ff5\u3002\u7b80\u5355\u8bf4\u5c31\u662f\u6709\u591a\u5927\u80fd\u529b\u505a\u591a\u5927\u7684\u4e8b\uff0c\u4e0e\u7cfb\u7edf\u76f8\u5173\u7684\u4e00\u4e9b\u7279\u522b\u5173\u952e\u7684\u64cd\u4f5c\u5fc5\u987b\u7531\u6700\u9ad8\u7279\u6743\u7684\u7a0b\u5e8f\u6765\u5b8c\u6210\u3002Intel \u7684 x86 \u67b6\u6784\u7684 CPU \u63d0\u4f9b\u4e86 0 \u5230 3 \u56db\u4e2a\u7279\u6743\u7ea7\uff0c\u6570\u5b57\u8d8a\u5c0f\uff0c\u7279\u6743\u8d8a\u9ad8\uff0cLinux \u64cd\u4f5c\u7cfb\u7edf\u4e2d\u4e3b\u8981\u91c7\u7528\u4e86 0 \u548c 3 \u4e24\u4e2a\u7279\u6743\u7ea7\uff0c\u5206\u522b\u5bf9\u5e94\u7684\u5c31\u662f\u5185\u6838\u6001\u548c\u7528\u6237\u6001\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd0\u884c\u4e8e\u7528\u6237\u6001\u7684\u8fdb\u7a0b\u53ef\u4ee5\u6267\u884c\u7684\u64cd\u4f5c\u548c\u8bbf\u95ee\u7684\u8d44\u6e90\u90fd\u4f1a\u53d7\u5230\u6781\u5927\u7684\u9650\u5236\uff0c\u800c\u8fd0\u884c\u5728\u5185\u6838\u6001\u7684\u8fdb\u7a0b\u5219\u53ef\u4ee5\u6267\u884c\u4efb\u4f55\u64cd\u4f5c\u5e76\u4e14\u5728\u8d44\u6e90\u7684\u4f7f\u7528\u4e0a\u6ca1\u6709\u9650\u5236\u3002\u5f88\u591a\u7a0b\u5e8f\u5f00\u59cb\u65f6\u8fd0\u884c\u4e8e\u7528\u6237\u6001\uff0c\u4f46\u5728\u6267\u884c\u7684\u8fc7\u7a0b\u4e2d\uff0c\u4e00\u4e9b\u64cd\u4f5c\u9700\u8981\u5728\u5185\u6838\u6743\u9650\u4e0b\u624d\u80fd\u6267\u884c\uff0c\u8fd9\u5c31\u6d89\u53ca\u5230\u4e00\u4e2a\u4ece\u7528\u6237\u6001\u5207\u6362\u5230\u5185\u6838\u6001\u7684\u8fc7\u7a0b\u3002\u6bd4\u5982 C \u51fd\u6570\u5e93\u4e2d\u7684\u5185\u5b58\u5206\u914d\u51fd\u6570 malloc()\uff0c\u5b83\u5177\u4f53\u662f\u4f7f\u7528 sbrk() \u7cfb\u7edf\u8c03\u7528\u6765\u5206\u914d\u5185\u5b58\uff0c\u5f53 malloc \u8c03\u7528 sbrk() \u7684\u65f6\u5019\u5c31\u6d89\u53ca\u4e00\u6b21\u4ece\u7528\u6237\u6001\u5230\u5185\u6838\u6001\u7684\u5207\u6362\uff0c\u7c7b\u4f3c\u7684\u51fd\u6570\u8fd8\u6709 printf()\uff0c\u8c03\u7528\u7684\u662f wirte() \u7cfb\u7edf\u8c03\u7528\u6765\u8f93\u51fa\u5b57\u7b26\u4e32\uff0c\u7b49\u7b49\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7528\u6237\u8fdb\u7a0b\u5728\u7cfb\u7edf\u4e2d\u8fd0\u884c\u65f6\uff0c\u5927\u90e8\u5206\u65f6\u95f4\u662f\u5904\u5728\u7528\u6237\u6001\u7a7a\u95f4\u91cc\u7684\uff0c\u5728\u5176\u9700\u8981\u64cd\u4f5c\u7cfb\u7edf\u5e2e\u52a9\u5b8c\u6210\u4e00\u4e9b\u7528\u6237\u6001\u6ca1\u6709\u7279\u6743\u548c\u80fd\u529b\u5b8c\u6210\u7684\u64cd\u4f5c\u65f6\u5c31\u9700\u8981\u5207\u6362\u5230\u5185\u6838\u6001\u3002\u90a3\u4e48\u7528\u6237\u8fdb\u7a0b\u5982\u4f55\u5207\u6362\u5230\u5185\u6838\u6001\u53bb\u4f7f\u7528\u90a3\u4e9b\u5185\u6838\u8d44\u6e90\u5462\uff1f\u7b54\u6848\u662f\uff1a1) \u7cfb\u7edf\u8c03\u7528\uff08trap\uff09\uff0c2) \u5f02\u5e38\uff08exception\uff09\u548c 3) \u4e2d\u65ad\uff08interrupt\uff09\u3002<\/p>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section><strong>\u7cfb\u7edf\u8c03\u7528<\/strong>\uff1a\u7528\u6237\u8fdb\u7a0b\u4e3b\u52a8\u53d1\u8d77\u7684\u64cd\u4f5c\u3002\u7528\u6237\u6001\u8fdb\u7a0b\u53d1\u8d77\u7cfb\u7edf\u8c03\u7528\u4e3b\u52a8\u8981\u6c42\u5207\u6362\u5230\u5185\u6838\u6001\uff0c\u9677\u5165\u5185\u6838\u4e4b\u540e\uff0c\u7531\u64cd\u4f5c\u7cfb\u7edf\u6765\u64cd\u4f5c\u7cfb\u7edf\u8d44\u6e90\uff0c\u5b8c\u6210\u4e4b\u540e\u518d\u8fd4\u56de\u5230\u8fdb\u7a0b\u3002<\/section>\n<\/li>\n<li>\n<section><strong>\u5f02\u5e38<\/strong>\uff1a\u88ab\u52a8\u7684\u64cd\u4f5c\uff0c\u4e14\u7528\u6237\u8fdb\u7a0b\u65e0\u6cd5\u9884\u6d4b\u5176\u53d1\u751f\u7684\u65f6\u673a\u3002\u5f53\u7528\u6237\u8fdb\u7a0b\u5728\u8fd0\u884c\u671f\u95f4\u53d1\u751f\u4e86\u5f02\u5e38\uff08\u6bd4\u5982\u67d0\u6761\u6307\u4ee4\u51fa\u4e86\u95ee\u9898\uff09\uff0c\u8fd9\u65f6\u4f1a\u89e6\u53d1\u7531\u5f53\u524d\u8fd0\u884c\u8fdb\u7a0b\u5207\u6362\u5230\u5904\u7406\u6b64\u5f02\u5e38\u7684\u5185\u6838\u76f8\u5173\u8fdb\u7a0b\u4e2d\uff0c\u4e5f\u5373\u662f\u5207\u6362\u5230\u4e86\u5185\u6838\u6001\u3002\u5f02\u5e38\u5305\u62ec\u7a0b\u5e8f\u8fd0\u7b97\u5f15\u8d77\u7684\u5404\u79cd\u9519\u8bef\u5982\u9664 0\u3001\u7f13\u51b2\u533a\u6ea2\u51fa\u3001\u7f3a\u9875\u7b49\u3002<\/section>\n<\/li>\n<li>\n<section><strong>\u4e2d\u65ad<\/strong>\uff1a\u5f53\u5916\u56f4\u8bbe\u5907\u5b8c\u6210\u7528\u6237\u8bf7\u6c42\u7684\u64cd\u4f5c\u540e\uff0c\u4f1a\u5411 CPU \u53d1\u51fa\u76f8\u5e94\u7684\u4e2d\u65ad\u4fe1\u53f7\uff0c\u8fd9\u65f6 CPU \u4f1a\u6682\u505c\u6267\u884c\u4e0b\u4e00\u6761\u5373\u5c06\u8981\u6267\u884c\u7684\u6307\u4ee4\u800c\u8f6c\u5230\u4e0e\u4e2d\u65ad\u4fe1\u53f7\u5bf9\u5e94\u7684\u5904\u7406\u7a0b\u5e8f\u53bb\u6267\u884c\uff0c\u5982\u679c\u524d\u9762\u6267\u884c\u7684\u6307\u4ee4\u662f\u7528\u6237\u6001\u4e0b\u7684\u7a0b\u5e8f\uff0c\u90a3\u4e48\u8f6c\u6362\u7684\u8fc7\u7a0b\u81ea\u7136\u5c31\u4f1a\u662f\u4ece\u7528\u6237\u6001\u5230\u5185\u6838\u6001\u7684\u5207\u6362\u3002\u4e2d\u65ad\u5305\u62ec I\/O \u4e2d\u65ad\u3001\u5916\u90e8\u4fe1\u53f7\u4e2d\u65ad\u3001\u5404\u79cd\u5b9a\u65f6\u5668\u5f15\u8d77\u7684\u65f6\u949f\u4e2d\u65ad\u7b49\u3002\u4e2d\u65ad\u548c\u5f02\u5e38\u7c7b\u4f3c\uff0c\u90fd\u662f\u901a\u8fc7\u4e2d\u65ad\u5411\u91cf\u8868\u6765\u627e\u5230\u76f8\u5e94\u7684\u5904\u7406\u7a0b\u5e8f\u8fdb\u884c\u5904\u7406\u3002\u533a\u522b\u5728\u4e8e\uff0c\u4e2d\u65ad\u6765\u81ea\u5904\u7406\u5668\u5916\u90e8\uff0c\u4e0d\u662f\u7531\u4efb\u4f55\u4e00\u6761\u4e13\u95e8\u7684\u6307\u4ee4\u9020\u6210\uff0c\u800c\u5f02\u5e38\u662f\u6267\u884c\u5f53\u524d\u6307\u4ee4\u7684\u7ed3\u679c\u3002<\/section>\n<\/li>\n<\/ul>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u901a\u8fc7\u4e0a\u9762\u7684\u5206\u6790\uff0c\u6211\u4eec\u53ef\u4ee5\u5f97\u51fa Linux \u7684\u5185\u90e8\u5c42\u7ea7\u53ef\u5206\u4e3a\u4e09\u5927\u90e8\u5206\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u7a7a\u95f4\uff1b<\/section>\n<\/li>\n<li>\n<section>\u5185\u6838\u7a7a\u95f4\uff1b<\/section>\n<\/li>\n<li>\n<section>\u786c\u4ef6\u3002<\/section>\n<\/li>\n<\/ol>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOonb0mgkGwaicWUvfXKLJouhTAMm50e2LJrTso9Cjic5FVFVuSVlUGrbTw\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.7016666666666667\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOonb0mgkGwaicWUvfXKLJouhTAMm50e2LJrTso9Cjic5FVFVuSVlUGrbTw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<h3 data-tool=\"mdnice\u7f16\u8f91\u5668\">Linux I\/O<\/h3>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">I\/O \u7f13\u51b2\u533a<\/h4>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoxmcyx9wDy96RYiaAwjpRLcDRhXzhrM6JpyYm9ON9ia8pAotxxKZfnhSg\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.8627951499680919\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoxmcyx9wDy96RYiaAwjpRLcDRhXzhrM6JpyYm9ON9ia8pAotxxKZfnhSg\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1567\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5728 Linux \u4e2d\uff0c\u5f53\u7a0b\u5e8f\u8c03\u7528\u5404\u7c7b\u6587\u4ef6\u64cd\u4f5c\u51fd\u6570\u540e\uff0c\u7528\u6237\u6570\u636e\uff08User Data\uff09\u5230\u8fbe\u78c1\u76d8\uff08Disk\uff09\u7684\u6d41\u7a0b\u5982\u4e0a\u56fe\u6240\u793a\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u56fe\u4e2d\u63cf\u8ff0\u4e86 Linux \u4e2d\u6587\u4ef6\u64cd\u4f5c\u51fd\u6570\u7684\u5c42\u7ea7\u5173\u7cfb\u548c\u5185\u5b58\u7f13\u5b58\u5c42\u7684\u5b58\u5728\u4f4d\u7f6e\uff0c\u4e2d\u95f4\u7684\u9ed1\u8272\u5b9e\u7ebf\u662f\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u5206\u754c\u7ebf\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>read(2)\/write(2)<\/code>\u00a0\u662f Linux \u7cfb\u7edf\u4e2d\u6700\u57fa\u672c\u7684 I\/O \u8bfb\u5199\u7cfb\u7edf\u8c03\u7528\uff0c\u6211\u4eec\u5f00\u53d1\u64cd\u4f5c I\/O \u7684\u7a0b\u5e8f\u65f6\u5fc5\u5b9a\u4f1a\u63a5\u89e6\u5230\u5b83\u4eec\uff0c\u800c\u5728\u8fd9\u4e24\u4e2a\u7cfb\u7edf\u8c03\u7528\u548c\u771f\u5b9e\u7684\u78c1\u76d8\u8bfb\u5199\u4e4b\u95f4\u5b58\u5728\u4e00\u5c42\u79f0\u4e3a\u00a0<code>Kernel buffer cache<\/code>\u00a0\u7684\u7f13\u51b2\u533a\u7f13\u5b58\u3002\u5728 Linux \u4e2d I\/O \u7f13\u5b58\u5176\u5b9e\u53ef\u4ee5\u7ec6\u5206\u4e3a\u4e24\u4e2a\uff1a<code>Page Cache<\/code>\u00a0\u548c\u00a0<code>Buffer Cache<\/code>\uff0c\u8fd9\u4e24\u4e2a\u5176\u5b9e\u662f\u4e00\u4f53\u4e24\u9762\uff0c\u5171\u540c\u7ec4\u6210\u4e86 Linux \u7684\u5185\u6838\u7f13\u51b2\u533a\uff08Kernel Buffer Cache\uff09\uff1a<\/p>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section><strong>\u8bfb\u78c1\u76d8<\/strong>\uff1a\u5185\u6838\u4f1a\u5148\u68c0\u67e5\u00a0<code>Page Cache<\/code>\u00a0\u91cc\u662f\u4e0d\u662f\u5df2\u7ecf\u7f13\u5b58\u4e86\u8fd9\u4e2a\u6570\u636e\uff0c\u82e5\u662f\uff0c\u76f4\u63a5\u4ece\u8fd9\u4e2a\u5185\u5b58\u7f13\u51b2\u533a\u91cc\u8bfb\u53d6\u8fd4\u56de\uff0c\u82e5\u5426\uff0c\u5219\u7a7f\u900f\u5230\u78c1\u76d8\u53bb\u8bfb\u53d6\uff0c\u7136\u540e\u518d\u7f13\u5b58\u5728\u00a0<code>Page Cache<\/code>\u00a0\u91cc\uff0c\u4ee5\u5907\u4e0b\u6b21\u7f13\u5b58\u547d\u4e2d\uff1b<\/section>\n<\/li>\n<li>\n<section><strong>\u5199\u78c1\u76d8<\/strong>\uff1a\u5185\u6838\u76f4\u63a5\u628a\u6570\u636e\u5199\u5165\u00a0<code>Page Cache<\/code>\uff0c\u5e76\u628a\u5bf9\u5e94\u7684\u9875\u6807\u8bb0\u4e3a dirty\uff0c\u6dfb\u52a0\u5230 dirty list \u91cc\uff0c\u7136\u540e\u5c31\u76f4\u63a5\u8fd4\u56de\uff0c\u5185\u6838\u4f1a\u5b9a\u671f\u628a dirty list \u7684\u9875\u7f13\u5b58 flush \u5230\u78c1\u76d8\uff0c\u4fdd\u8bc1\u9875\u7f13\u5b58\u548c\u78c1\u76d8\u7684\u6700\u7ec8\u4e00\u81f4\u6027\u3002<\/section>\n<\/li>\n<\/ul>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>Page Cache<\/code>\u00a0\u4f1a\u901a\u8fc7\u9875\u9762\u7f6e\u6362\u7b97\u6cd5\u5982 LRU \u5b9a\u671f\u6dd8\u6c70\u65e7\u7684\u9875\u9762\uff0c\u52a0\u8f7d\u65b0\u7684\u9875\u9762\u3002\u53ef\u4ee5\u770b\u51fa\uff0c\u6240\u8c13 I\/O \u7f13\u51b2\u533a\u7f13\u5b58\u5c31\u662f\u5728\u5185\u6838\u548c\u78c1\u76d8\u3001\u7f51\u5361\u7b49\u5916\u8bbe\u4e4b\u95f4\u7684\u4e00\u5c42\u7f13\u51b2\u533a\uff0c\u7528\u6765\u63d0\u5347\u8bfb\u5199\u6027\u80fd\u7684\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5728 Linux \u8fd8\u4e0d\u652f\u6301\u865a\u62df\u5185\u5b58\u6280\u672f\u4e4b\u524d\uff0c\u8fd8\u6ca1\u6709\u9875\u7684\u6982\u5ff5\uff0c\u56e0\u6b64\u00a0<code>Buffer Cache<\/code>\u00a0\u662f\u57fa\u4e8e\u64cd\u4f5c\u7cfb\u7edf\u8bfb\u5199\u78c1\u76d8\u7684\u6700\u5c0f\u5355\u4f4d &#8212; \u5757\uff08block\uff09\u6765\u8fdb\u884c\u7684\uff0c\u6240\u6709\u7684\u78c1\u76d8\u5757\u64cd\u4f5c\u90fd\u662f\u901a\u8fc7\u00a0<code>Buffer Cache<\/code>\u00a0\u6765\u52a0\u901f\uff0cLinux \u5f15\u5165\u865a\u62df\u5185\u5b58\u7684\u673a\u5236\u6765\u7ba1\u7406\u5185\u5b58\u540e\uff0c\u9875\u6210\u4e3a\u865a\u62df\u5185\u5b58\u7ba1\u7406\u7684\u6700\u5c0f\u5355\u4f4d\uff0c\u56e0\u6b64\u4e5f\u5f15\u5165\u4e86\u00a0<code>Page Cache<\/code>\u00a0\u6765\u7f13\u5b58 Linux \u6587\u4ef6\u5185\u5bb9\uff0c\u4e3b\u8981\u7528\u6765\u4f5c\u4e3a\u6587\u4ef6\u7cfb\u7edf\u4e0a\u7684\u6587\u4ef6\u6570\u636e\u7684\u7f13\u5b58\uff0c\u63d0\u5347\u8bfb\u5199\u6027\u80fd\uff0c\u5e38\u89c1\u7684\u662f\u9488\u5bf9\u6587\u4ef6\u7684\u00a0<code>read()\/write()<\/code>\u00a0\u64cd\u4f5c\uff0c\u53e6\u5916\u4e5f\u5305\u62ec\u4e86\u901a\u8fc7\u00a0<code>mmap()<\/code>\u00a0\u6620\u5c04\u4e4b\u540e\u7684\u5757\u8bbe\u5907\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u4e8b\u5b9e\u4e0a Page Cache \u8d1f\u8d23\u4e86\u5927\u90e8\u5206\u7684\u5757\u8bbe\u5907\u6587\u4ef6\u7684\u7f13\u5b58\u5de5\u4f5c\u3002\u800c\u00a0<code>Buffer Cache<\/code>\u00a0\u7528\u6765\u5728\u7cfb\u7edf\u5bf9\u5757\u8bbe\u5907\u8fdb\u884c\u8bfb\u5199\u7684\u65f6\u5019\uff0c\u5bf9\u5757\u8fdb\u884c\u6570\u636e\u7f13\u5b58\u7684\u7cfb\u7edf\u6765\u4f7f\u7528\uff0c\u5b9e\u9645\u4e0a\u8d1f\u8d23\u6240\u6709\u5bf9\u78c1\u76d8\u7684 I\/O \u8bbf\u95ee\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoOpkFTjCdyo3WJZAEnXiahicSCHfFicbK92ICXw3KSPogKaf9doRDaku9Q\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.6316666666666667\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoOpkFTjCdyo3WJZAEnXiahicSCHfFicbK92ICXw3KSPogKaf9doRDaku9Q\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u56e0\u4e3a\u00a0<code>Buffer Cache<\/code>\u00a0\u662f\u5bf9\u7c92\u5ea6\u66f4\u7ec6\u7684\u8bbe\u5907\u5757\u7684\u7f13\u5b58\uff0c\u800c\u00a0<code>Page Cache<\/code>\u00a0\u662f\u57fa\u4e8e\u865a\u62df\u5185\u5b58\u7684\u9875\u5355\u5143\u7f13\u5b58\uff0c\u56e0\u6b64\u8fd8\u662f\u4f1a\u57fa\u4e8e\u00a0<code>Buffer Cache<\/code>\uff0c\u4e5f\u5c31\u662f\u8bf4\u5982\u679c\u662f\u7f13\u5b58\u6587\u4ef6\u5185\u5bb9\u6570\u636e\u5c31\u4f1a\u5728\u5185\u5b58\u91cc\u7f13\u5b58\u4e24\u4efd\u76f8\u540c\u7684\u6570\u636e\uff0c\u8fd9\u5c31\u4f1a\u5bfc\u81f4\u540c\u4e00\u4efd\u6587\u4ef6\u4fdd\u5b58\u4e86\u4e24\u4efd\uff0c\u5197\u4f59\u4e14\u4f4e\u6548\u3002\u53e6\u5916\u4e00\u4e2a\u95ee\u9898\u662f\uff0c\u8c03\u7528\u00a0<code>write<\/code>\u00a0\u540e\uff0c\u6709\u6548\u6570\u636e\u662f\u5728\u00a0<code>Buffer Cache<\/code>\u00a0\u4e2d\uff0c\u800c\u975e\u00a0<code>Page Cache<\/code>\u00a0\u4e2d\u3002\u8fd9\u5c31\u5bfc\u81f4\u00a0<code>mmap<\/code>\u00a0\u8bbf\u95ee\u7684\u6587\u4ef6\u6570\u636e\u53ef\u80fd\u5b58\u5728\u4e0d\u4e00\u81f4\u95ee\u9898\u3002\u4e3a\u4e86\u89c4\u907f\u8fd9\u4e2a\u95ee\u9898\uff0c\u6240\u6709\u57fa\u4e8e\u78c1\u76d8\u6587\u4ef6\u7cfb\u7edf\u7684\u00a0<code>write<\/code>\uff0c\u90fd\u9700\u8981\u8c03\u7528\u00a0<code>update_vm_cache()<\/code>\u00a0\u51fd\u6570\uff0c\u8be5\u64cd\u4f5c\u4f1a\u628a\u8c03\u7528\u00a0<code>write<\/code>\u00a0\u4e4b\u540e\u7684\u00a0<code>Buffer Cache<\/code>\u00a0\u66f4\u65b0\u5230\u00a0<code>Page Cache<\/code>\u00a0\u53bb\u3002\u7531\u4e8e\u6709\u8fd9\u4e9b\u8bbe\u8ba1\u4e0a\u7684\u5f0a\u7aef\uff0c\u56e0\u6b64\u5728 Linux 2.4 \u7248\u672c\u4e4b\u540e\uff0ckernel \u5c31\u5c06\u4e24\u8005\u8fdb\u884c\u4e86\u7edf\u4e00\uff0c<code>Buffer Cache<\/code>\u00a0\u4e0d\u518d\u4ee5\u72ec\u7acb\u7684\u5f62\u5f0f\u5b58\u5728\uff0c\u800c\u662f\u4ee5\u878d\u5408\u7684\u65b9\u5f0f\u5b58\u5728\u4e8e\u00a0<code>Page Cache<\/code>\u00a0\u4e2d\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOolQQP7RmRJXe0xcoUHaxGVKXtzbld4tYFOaiaeIFR5Ax1WSVEyZNvWKQ\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.6316666666666667\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOolQQP7RmRJXe0xcoUHaxGVKXtzbld4tYFOaiaeIFR5Ax1WSVEyZNvWKQ\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u878d\u5408\u4e4b\u540e\u5c31\u53ef\u4ee5\u7edf\u4e00\u64cd\u4f5c\u00a0<code>Page Cache<\/code>\u00a0\u548c\u00a0<code>Buffer Cache<\/code>\uff1a\u5904\u7406\u6587\u4ef6 I\/O \u7f13\u5b58\u4ea4\u7ed9\u00a0<code>Page Cache<\/code>\uff0c\u800c\u5f53\u5e95\u5c42 RAW device \u5237\u65b0\u6570\u636e\u65f6\u4ee5\u00a0<code>Buffer Cache<\/code>\u00a0\u7684\u5757\u5355\u4f4d\u6765\u5b9e\u9645\u5904\u7406\u3002<\/p>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">I\/O \u6a21\u5f0f<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5728 Linux \u6216\u8005\u5176\u4ed6 Unix-like \u64cd\u4f5c\u7cfb\u7edf\u91cc\uff0cI\/O \u6a21\u5f0f\u4e00\u822c\u6709\u4e09\u79cd\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7a0b\u5e8f\u63a7\u5236 I\/O<\/section>\n<\/li>\n<li>\n<section>\u4e2d\u65ad\u9a71\u52a8 I\/O<\/section>\n<\/li>\n<li>\n<section>DMA I\/O<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e0b\u9762\u6211\u5206\u522b\u8be6\u7ec6\u5730\u8bb2\u89e3\u4e00\u4e0b\u8fd9\u4e09\u79cd I\/O \u6a21\u5f0f\u3002<\/p>\n<h5 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7a0b\u5e8f\u63a7\u5236 I\/O<\/h5>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u662f\u6700\u7b80\u5355\u7684\u4e00\u79cd I\/O \u6a21\u5f0f\uff0c\u4e5f\u53eb\u5fd9\u7b49\u5f85\u6216\u8005\u8f6e\u8be2\uff1a\u7528\u6237\u901a\u8fc7\u53d1\u8d77\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\uff0c\u9677\u5165\u5185\u6838\u6001\uff0c\u5185\u6838\u5c06\u7cfb\u7edf\u8c03\u7528\u7ffb\u8bd1\u6210\u4e00\u4e2a\u5bf9\u5e94\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u7684\u8fc7\u7a0b\u8c03\u7528\uff0c\u63a5\u7740\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u4f1a\u542f\u52a8 I\/O \u4e0d\u65ad\u5faa\u73af\u53bb\u68c0\u67e5\u8be5\u8bbe\u5907\uff0c\u770b\u770b\u662f\u5426\u5df2\u7ecf\u5c31\u7eea\uff0c\u4e00\u822c\u901a\u8fc7\u8fd4\u56de\u7801\u6765\u8868\u793a\uff0cI\/O \u7ed3\u675f\u4e4b\u540e\uff0c\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u4f1a\u628a\u6570\u636e\u9001\u5230\u6307\u5b9a\u7684\u5730\u65b9\u5e76\u8fd4\u56de\uff0c\u5207\u56de\u7528\u6237\u6001\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6bd4\u5982\u53d1\u8d77\u7cfb\u7edf\u8c03\u7528\u00a0<code>read()<\/code>\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOosXudQhykMVcPCTXichGsAPmbAdQbCibwYicahtbaOF3ya8DnyFZHI1lSg\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.5257393209200438\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOosXudQhykMVcPCTXichGsAPmbAdQbCibwYicahtbaOF3ya8DnyFZHI1lSg\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1826\" data-fail=\"0\" \/><\/figure>\n<h5 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e2d\u65ad\u9a71\u52a8 I\/O<\/h5>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7b2c\u4e8c\u79cd I\/O \u6a21\u5f0f\u662f\u5229\u7528\u4e2d\u65ad\u6765\u5b9e\u73b0\u7684\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOovJZXPBTjuByy0s9zUYpqSxBnLPaCLQlekb6env5wGrJpib25FrUvg8A\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.5358333333333334\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOovJZXPBTjuByy0s9zUYpqSxBnLPaCLQlekb6env5wGrJpib25FrUvg8A\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6d41\u7a0b\u5982\u4e0b\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u53d1\u8d77\u4e00\u4e2a\u00a0<code>read()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u8bfb\u53d6\u78c1\u76d8\u6587\u4ef6\uff0c\u9677\u5165\u5185\u6838\u6001\u5e76\u7531\u5176\u6240\u5728\u7684 CPU \u901a\u8fc7\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u5411\u8bbe\u5907\u5bc4\u5b58\u5668\u5199\u5165\u4e00\u4e2a\u901a\u77e5\u4fe1\u53f7\uff0c\u544a\u77e5\u8bbe\u5907\u63a7\u5236\u5668 (\u6211\u4eec\u8fd9\u91cc\u662f\u78c1\u76d8\u63a7\u5236\u5668)\u8981\u8bfb\u53d6\u6570\u636e\uff1b<\/section>\n<\/li>\n<li>\n<section>\u78c1\u76d8\u63a7\u5236\u5668\u542f\u52a8\u78c1\u76d8\u8bfb\u53d6\u7684\u8fc7\u7a0b\uff0c\u628a\u6570\u636e\u4ece\u78c1\u76d8\u62f7\u8d1d\u5230\u78c1\u76d8\u63a7\u5236\u5668\u7f13\u51b2\u533a\u91cc\uff1b<\/section>\n<\/li>\n<li>\n<section>\u5b8c\u6210\u62f7\u8d1d\u4e4b\u540e\u78c1\u76d8\u63a7\u5236\u5668\u4f1a\u901a\u8fc7\u603b\u7ebf\u53d1\u9001\u4e00\u4e2a\u4e2d\u65ad\u4fe1\u53f7\u5230\u4e2d\u65ad\u63a7\u5236\u5668\uff0c\u5982\u679c\u6b64\u65f6\u4e2d\u65ad\u63a7\u5236\u5668\u624b\u5934\u8fd8\u6709\u6b63\u5728\u5904\u7406\u7684\u4e2d\u65ad\u6216\u8005\u6709\u4e00\u4e2a\u548c\u8be5\u4e2d\u65ad\u4fe1\u53f7\u540c\u65f6\u5230\u8fbe\u7684\u66f4\u9ad8\u4f18\u5148\u7ea7\u7684\u4e2d\u65ad\uff0c\u5219\u8fd9\u4e2a\u4e2d\u65ad\u4fe1\u53f7\u5c06\u88ab\u5ffd\u7565\uff0c\u800c\u78c1\u76d8\u63a7\u5236\u5668\u4f1a\u5728\u540e\u9762\u6301\u7eed\u53d1\u9001\u4e2d\u65ad\u4fe1\u53f7\u76f4\u81f3\u4e2d\u65ad\u63a7\u5236\u5668\u53d7\u7406\uff1b<\/section>\n<\/li>\n<li>\n<section>\u4e2d\u65ad\u63a7\u5236\u5668\u6536\u5230\u78c1\u76d8\u63a7\u5236\u5668\u7684\u4e2d\u65ad\u4fe1\u53f7\u4e4b\u540e\u4f1a\u901a\u8fc7\u5730\u5740\u603b\u7ebf\u5b58\u5165\u4e00\u4e2a\u78c1\u76d8\u8bbe\u5907\u7684\u7f16\u53f7\uff0c\u8868\u793a\u8fd9\u6b21\u4e2d\u65ad\u9700\u8981\u5173\u6ce8\u7684\u8bbe\u5907\u662f\u78c1\u76d8\uff1b<\/section>\n<\/li>\n<li>\n<section>\u4e2d\u65ad\u63a7\u5236\u5668\u5411 CPU \u7f6e\u8d77\u4e00\u4e2a\u78c1\u76d8\u4e2d\u65ad\u4fe1\u53f7\uff1b<\/section>\n<\/li>\n<li>\n<section>CPU \u6536\u5230\u4e2d\u65ad\u4fe1\u53f7\u4e4b\u540e\u505c\u6b62\u5f53\u524d\u7684\u5de5\u4f5c\uff0c\u628a\u5f53\u524d\u7684 PC\/PSW \u7b49\u5bc4\u5b58\u5668\u538b\u5165\u5806\u6808\u4fdd\u5b58\u73b0\u573a\uff0c\u7136\u540e\u4ece\u5730\u5740\u603b\u7ebf\u53d6\u51fa\u8bbe\u5907\u7f16\u53f7\uff0c\u901a\u8fc7\u7f16\u53f7\u627e\u5230\u4e2d\u65ad\u5411\u91cf\u6240\u5305\u542b\u7684\u4e2d\u65ad\u670d\u52a1\u7684\u5165\u53e3\u5730\u5740\uff0c\u538b\u5165 PC \u5bc4\u5b58\u5668\uff0c\u5f00\u59cb\u8fd0\u884c\u78c1\u76d8\u4e2d\u65ad\u670d\u52a1\uff0c\u628a\u6570\u636e\u4ece\u78c1\u76d8\u63a7\u5236\u5668\u7684\u7f13\u51b2\u533a\u62f7\u8d1d\u5230\u4e3b\u5b58\u91cc\u7684\u5185\u6838\u7f13\u51b2\u533a\uff1b<\/section>\n<\/li>\n<li>\n<section>\u6700\u540e CPU \u518d\u628a\u6570\u636e\u4ece\u5185\u6838\u7f13\u51b2\u533a\u62f7\u8d1d\u5230\u7528\u6237\u7f13\u51b2\u533a\uff0c\u5b8c\u6210\u8bfb\u53d6\u64cd\u4f5c\uff0c<code>read()<\/code>\u00a0\u8fd4\u56de\uff0c\u5207\u6362\u56de\u7528\u6237\u6001\u3002<\/section>\n<\/li>\n<\/ol>\n<h5 data-tool=\"mdnice\u7f16\u8f91\u5668\">DMA I\/O<\/h5>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5e76\u53d1\u7cfb\u7edf\u7684\u6027\u80fd\u9ad8\u4f4e\u7a76\u5176\u6839\u672c\uff0c\u662f\u53d6\u51b3\u4e8e\u5982\u4f55\u5bf9 CPU \u8d44\u6e90\u7684\u9ad8\u6548\u8c03\u5ea6\u548c\u4f7f\u7528\uff0c\u800c\u56de\u5934\u770b\u524d\u9762\u7684\u4e2d\u65ad\u9a71\u52a8 I\/O \u6a21\u5f0f\u7684\u6d41\u7a0b\uff0c\u53ef\u4ee5\u53d1\u73b0\u7b2c 6\u30017 \u6b65\u7684\u6570\u636e\u62f7\u8d1d\u5de5\u4f5c\u90fd\u662f\u7531 CPU \u4eb2\u81ea\u5b8c\u6210\u7684\uff0c\u4e5f\u5c31\u662f\u5728\u8fd9\u4e24\u6b21\u6570\u636e\u62f7\u8d1d\u9636\u6bb5\u4e2d CPU \u662f\u5b8c\u5168\u88ab\u5360\u7528\u800c\u4e0d\u80fd\u5904\u7406\u5176\u4ed6\u5de5\u4f5c\u7684\uff0c\u90a3\u4e48\u8fd9\u91cc\u660e\u663e\u662f\u6709\u4f18\u5316\u7a7a\u95f4\u7684\uff1b\u7b2c 7 \u6b65\u7684\u6570\u636e\u62f7\u8d1d\u662f\u4ece\u5185\u6838\u7f13\u51b2\u533a\u5230\u7528\u6237\u7f13\u51b2\u533a\uff0c\u90fd\u662f\u5728\u4e3b\u5b58\u91cc\uff0c\u6240\u4ee5\u8fd9\u4e00\u6b65\u53ea\u80fd\u7531 CPU \u4eb2\u81ea\u5b8c\u6210\uff0c\u4f46\u662f\u7b2c 6 \u6b65\u7684\u6570\u636e\u62f7\u8d1d\uff0c\u662f\u4ece\u78c1\u76d8\u63a7\u5236\u5668\u7684\u7f13\u51b2\u533a\u5230\u4e3b\u5b58\uff0c\u662f\u4e24\u4e2a\u8bbe\u5907\u4e4b\u95f4\u7684\u6570\u636e\u4f20\u8f93\uff0c\u8fd9\u4e00\u6b65\u5e76\u975e\u4e00\u5b9a\u8981 CPU \u6765\u5b8c\u6210\uff0c\u53ef\u4ee5\u501f\u52a9 DMA \u6765\u5b8c\u6210\uff0c\u51cf\u8f7b CPU \u7684\u8d1f\u62c5\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">DMA \u5168\u79f0\u662f Direct Memory Access\uff0c\u4e5f\u5373\u76f4\u63a5\u5b58\u50a8\u5668\u5b58\u53d6\uff0c\u662f\u4e00\u79cd\u7528\u6765\u63d0\u4f9b\u5728\u5916\u8bbe\u548c\u5b58\u50a8\u5668\u4e4b\u95f4\u6216\u8005\u5b58\u50a8\u5668\u548c\u5b58\u50a8\u5668\u4e4b\u95f4\u7684\u9ad8\u901f\u6570\u636e\u4f20\u8f93\u3002\u6574\u4e2a\u8fc7\u7a0b\u65e0\u987b CPU \u53c2\u4e0e\uff0c\u6570\u636e\u76f4\u63a5\u901a\u8fc7 DMA \u63a7\u5236\u5668\u8fdb\u884c\u5feb\u901f\u5730\u79fb\u52a8\u62f7\u8d1d\uff0c\u8282\u7701 CPU \u7684\u8d44\u6e90\u53bb\u505a\u5176\u4ed6\u5de5\u4f5c\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u76ee\u524d\uff0c\u5927\u90e8\u5206\u7684\u8ba1\u7b97\u673a\u90fd\u914d\u5907\u4e86 DMA \u63a7\u5236\u5668\uff0c\u800c DMA \u6280\u672f\u4e5f\u652f\u6301\u5927\u90e8\u5206\u7684\u5916\u8bbe\u548c\u5b58\u50a8\u5668\u3002\u501f\u52a9\u4e8e DMA \u673a\u5236\uff0c\u8ba1\u7b97\u673a\u7684 I\/O \u8fc7\u7a0b\u5c31\u80fd\u66f4\u52a0\u9ad8\u6548\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOow9ydHFNBqI7RBicAwIRc95FDCm0npSfXXd6TBVZZ4lSKA8axWicdAdKA\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.43890784982935155\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOow9ydHFNBqI7RBicAwIRc95FDCm0npSfXXd6TBVZZ4lSKA8axWicdAdKA\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1465\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">DMA \u63a7\u5236\u5668\u5185\u90e8\u5305\u542b\u82e5\u5e72\u4e2a\u53ef\u4ee5\u88ab CPU \u8bfb\u5199\u7684\u5bc4\u5b58\u5668\uff1a\u4e00\u4e2a\u4e3b\u5b58\u5730\u5740\u5bc4\u5b58\u5668 MAR\uff08\u5b58\u653e\u8981\u4ea4\u6362\u6570\u636e\u7684\u4e3b\u5b58\u5730\u5740\uff09\u3001\u4e00\u4e2a\u5916\u8bbe\u5730\u5740\u5bc4\u5b58\u5668 ADR\uff08\u5b58\u653e I\/O \u8bbe\u5907\u7684\u8bbe\u5907\u7801\uff0c\u6216\u8005\u662f\u8bbe\u5907\u4fe1\u606f\u5b58\u50a8\u533a\u7684\u5bfb\u5740\u4fe1\u606f\uff09\u3001\u4e00\u4e2a\u5b57\u8282\u6570\u5bc4\u5b58\u5668 WC\uff08\u5bf9\u4f20\u9001\u6570\u636e\u7684\u603b\u5b57\u6570\u8fdb\u884c\u7edf\u8ba1\uff09\u3001\u548c\u4e00\u4e2a\u6216\u591a\u4e2a\u63a7\u5236\u5bc4\u5b58\u5668\u3002<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u53d1\u8d77\u4e00\u4e2a\u00a0<code>read()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u8bfb\u53d6\u78c1\u76d8\u6587\u4ef6\uff0c\u9677\u5165\u5185\u6838\u6001\u5e76\u7531\u5176\u6240\u5728\u7684 CPU \u901a\u8fc7\u8bbe\u7f6e DMA \u63a7\u5236\u5668\u7684\u5bc4\u5b58\u5668\u5bf9\u5b83\u8fdb\u884c\u7f16\u7a0b\uff1a\u628a\u5185\u6838\u7f13\u51b2\u533a\u548c\u78c1\u76d8\u6587\u4ef6\u7684\u5730\u5740\u5206\u522b\u5199\u5165 MAR \u548c ADR \u5bc4\u5b58\u5668\uff0c\u7136\u540e\u628a\u671f\u671b\u8bfb\u53d6\u7684\u5b57\u8282\u6570\u5199\u5165 WC \u5bc4\u5b58\u5668\uff0c\u542f\u52a8 DMA \u63a7\u5236\u5668\uff1b<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u6839\u636e ADR \u5bc4\u5b58\u5668\u91cc\u7684\u4fe1\u606f\u77e5\u9053\u8fd9\u6b21 I\/O \u9700\u8981\u8bfb\u53d6\u7684\u5916\u8bbe\u662f\u78c1\u76d8\u7684\u67d0\u4e2a\u5730\u5740\uff0c\u4fbf\u5411\u78c1\u76d8\u63a7\u5236\u5668\u53d1\u51fa\u4e00\u4e2a\u547d\u4ee4\uff0c\u901a\u77e5\u5b83\u4ece\u78c1\u76d8\u8bfb\u53d6\u6570\u636e\u5230\u5176\u5185\u90e8\u7684\u7f13\u51b2\u533a\u91cc\uff1b<\/section>\n<\/li>\n<li>\n<section>\u78c1\u76d8\u63a7\u5236\u5668\u542f\u52a8\u78c1\u76d8\u8bfb\u53d6\u7684\u8fc7\u7a0b\uff0c\u628a\u6570\u636e\u4ece\u78c1\u76d8\u62f7\u8d1d\u5230\u78c1\u76d8\u63a7\u5236\u5668\u7f13\u51b2\u533a\u91cc\uff0c\u5e76\u5bf9\u7f13\u51b2\u533a\u5185\u6570\u636e\u7684\u6821\u9a8c\u548c\u8fdb\u884c\u68c0\u9a8c\uff0c\u5982\u679c\u6570\u636e\u662f\u6709\u6548\u7684\uff0c\u90a3\u4e48 DMA \u5c31\u53ef\u4ee5\u5f00\u59cb\u4e86\uff1b<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u901a\u8fc7\u603b\u7ebf\u5411\u78c1\u76d8\u63a7\u5236\u5668\u53d1\u51fa\u4e00\u4e2a\u8bfb\u8bf7\u6c42\u4fe1\u53f7\u4ece\u800c\u53d1\u8d77 DMA \u4f20\u8f93\uff0c\u8fd9\u4e2a\u4fe1\u53f7\u548c\u524d\u9762\u7684\u4e2d\u65ad\u9a71\u52a8 I\/O \u5c0f\u8282\u91cc CPU \u53d1\u7ed9\u78c1\u76d8\u63a7\u5236\u5668\u7684\u8bfb\u8bf7\u6c42\u662f\u4e00\u6837\u7684\uff0c\u5b83\u5e76\u4e0d\u77e5\u9053\u6216\u8005\u5e76\u4e0d\u5173\u5fc3\u8fd9\u4e2a\u8bfb\u8bf7\u6c42\u662f\u6765\u81ea CPU \u8fd8\u662f DMA \u63a7\u5236\u5668\uff1b<\/section>\n<\/li>\n<li>\n<section>\u7d27\u63a5\u7740 DMA \u63a7\u5236\u5668\u5c06\u5f15\u5bfc\u78c1\u76d8\u63a7\u5236\u5668\u5c06\u6570\u636e\u4f20\u8f93\u5230 MAR \u5bc4\u5b58\u5668\u91cc\u7684\u5730\u5740\uff0c\u4e5f\u5c31\u662f\u5185\u6838\u7f13\u51b2\u533a\uff1b<\/section>\n<\/li>\n<li>\n<section>\u6570\u636e\u4f20\u8f93\u5b8c\u6210\u4e4b\u540e\uff0c\u8fd4\u56de\u4e00\u4e2a ack \u7ed9 DMA \u63a7\u5236\u5668\uff0cWC \u5bc4\u5b58\u5668\u91cc\u7684\u503c\u4f1a\u51cf\u53bb\u76f8\u5e94\u7684\u6570\u636e\u957f\u5ea6\uff0c\u5982\u679c WC \u8fd8\u4e0d\u4e3a 0\uff0c\u5219\u91cd\u590d\u7b2c 4 \u6b65\u5230\u7b2c 6 \u6b65\uff0c\u4e00\u76f4\u5230 WC \u91cc\u7684\u5b57\u8282\u6570\u7b49\u4e8e 0\uff1b<\/section>\n<\/li>\n<li>\n<section>\u6536\u5230 ack \u4fe1\u53f7\u7684 DMA \u63a7\u5236\u5668\u4f1a\u901a\u8fc7\u603b\u7ebf\u53d1\u9001\u4e00\u4e2a\u4e2d\u65ad\u4fe1\u53f7\u5230\u4e2d\u65ad\u63a7\u5236\u5668\uff0c\u5982\u679c\u6b64\u65f6\u4e2d\u65ad\u63a7\u5236\u5668\u624b\u5934\u8fd8\u6709\u6b63\u5728\u5904\u7406\u7684\u4e2d\u65ad\u6216\u8005\u6709\u4e00\u4e2a\u548c\u8be5\u4e2d\u65ad\u4fe1\u53f7\u540c\u65f6\u5230\u8fbe\u7684\u66f4\u9ad8\u4f18\u5148\u7ea7\u7684\u4e2d\u65ad\uff0c\u5219\u8fd9\u4e2a\u4e2d\u65ad\u4fe1\u53f7\u5c06\u88ab\u5ffd\u7565\uff0c\u800c DMA \u63a7\u5236\u5668\u4f1a\u5728\u540e\u9762\u6301\u7eed\u53d1\u9001\u4e2d\u65ad\u4fe1\u53f7\u76f4\u81f3\u4e2d\u65ad\u63a7\u5236\u5668\u53d7\u7406\uff1b<\/section>\n<\/li>\n<li>\n<section>\u4e2d\u65ad\u63a7\u5236\u5668\u6536\u5230\u78c1\u76d8\u63a7\u5236\u5668\u7684\u4e2d\u65ad\u4fe1\u53f7\u4e4b\u540e\u4f1a\u901a\u8fc7\u5730\u5740\u603b\u7ebf\u5b58\u5165\u4e00\u4e2a\u4e3b\u5b58\u8bbe\u5907\u7684\u7f16\u53f7\uff0c\u8868\u793a\u8fd9\u6b21\u4e2d\u65ad\u9700\u8981\u5173\u6ce8\u7684\u8bbe\u5907\u662f\u4e3b\u5b58\uff1b<\/section>\n<\/li>\n<li>\n<section>\u4e2d\u65ad\u63a7\u5236\u5668\u5411 CPU \u7f6e\u8d77\u4e00\u4e2a DMA \u4e2d\u65ad\u7684\u4fe1\u53f7\uff1b<\/section>\n<\/li>\n<li>\n<section>CPU \u6536\u5230\u4e2d\u65ad\u4fe1\u53f7\u4e4b\u540e\u505c\u6b62\u5f53\u524d\u7684\u5de5\u4f5c\uff0c\u628a\u5f53\u524d\u7684 PC\/PSW \u7b49\u5bc4\u5b58\u5668\u538b\u5165\u5806\u6808\u4fdd\u5b58\u73b0\u573a\uff0c\u7136\u540e\u4ece\u5730\u5740\u603b\u7ebf\u53d6\u51fa\u8bbe\u5907\u7f16\u53f7\uff0c\u901a\u8fc7\u7f16\u53f7\u627e\u5230\u4e2d\u65ad\u5411\u91cf\u6240\u5305\u542b\u7684\u4e2d\u65ad\u670d\u52a1\u7684\u5165\u53e3\u5730\u5740\uff0c\u538b\u5165 PC \u5bc4\u5b58\u5668\uff0c\u5f00\u59cb\u8fd0\u884c DMA \u4e2d\u65ad\u670d\u52a1\uff0c\u628a\u6570\u636e\u4ece\u5185\u6838\u7f13\u51b2\u533a\u62f7\u8d1d\u5230\u7528\u6237\u7f13\u51b2\u533a\uff0c\u5b8c\u6210\u8bfb\u53d6\u64cd\u4f5c\uff0c<code>read()<\/code>\u00a0\u8fd4\u56de\uff0c\u5207\u6362\u56de\u7528\u6237\u6001\u3002<\/section>\n<\/li>\n<\/ol>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f20\u7edf I\/O \u8bfb\u5199\u6a21\u5f0f<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">Linux \u4e2d\u4f20\u7edf\u7684 I\/O \u8bfb\u5199\u662f\u901a\u8fc7\u00a0<code>read()\/write()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u5b8c\u6210\u7684\uff0c<code>read()<\/code>\u00a0\u628a\u6570\u636e\u4ece\u5b58\u50a8\u5668 (\u78c1\u76d8\u3001\u7f51\u5361\u7b49) \u8bfb\u53d6\u5230\u7528\u6237\u7f13\u51b2\u533a\uff0c<code>write()<\/code>\u00a0\u5219\u662f\u628a\u6570\u636e\u4ece\u7528\u6237\u7f13\u51b2\u533a\u5199\u51fa\u5230\u5b58\u50a8\u5668\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>#include\u00a0&lt;unistd.h&gt;\r\n\r\nssize_t\u00a0read(int\u00a0fd,\u00a0void\u00a0*buf,\u00a0size_t\u00a0count);\r\nssize_t\u00a0write(int\u00a0fd,\u00a0const\u00a0void\u00a0*buf,\u00a0size_t\u00a0count);\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e00\u6b21\u5b8c\u6574\u7684\u8bfb\u78c1\u76d8\u6587\u4ef6\u7136\u540e\u5199\u51fa\u5230\u7f51\u5361\u7684\u5e95\u5c42\u4f20\u8f93\u8fc7\u7a0b\u5982\u4e0b\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoHScbaM57GxicibUkBia1M4dWZfwiaA0fiaiaKFAibQbcBEsrjLMXeDqMDhicUg\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.57\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoHScbaM57GxicibUkBia1M4dWZfwiaA0fiaiaKFAibQbcBEsrjLMXeDqMDhicUg\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u53ef\u4ee5\u6e05\u695a\u770b\u5230\u8fd9\u91cc\u4e00\u5171\u89e6\u53d1\u4e86 4 \u6b21\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u4e0a\u4e0b\u6587\u5207\u6362\uff0c\u5206\u522b\u662f\u00a0<code>read()\/write()<\/code>\u00a0\u8c03\u7528\u548c\u8fd4\u56de\u65f6\u7684\u5207\u6362\uff0c2 \u6b21 DMA \u62f7\u8d1d\uff0c2 \u6b21 CPU \u62f7\u8d1d\uff0c\u52a0\u8d77\u6765\u4e00\u5171 4 \u6b21\u62f7\u8d1d\u64cd\u4f5c\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u901a\u8fc7\u5f15\u5165 DMA\uff0c\u6211\u4eec\u5df2\u7ecf\u628a Linux \u7684 I\/O \u8fc7\u7a0b\u4e2d\u7684 CPU \u62f7\u8d1d\u6b21\u6570\u4ece 4 \u6b21\u51cf\u5c11\u5230\u4e86 2 \u6b21\uff0c\u4f46\u662f CPU \u62f7\u8d1d\u4f9d\u7136\u662f\u4ee3\u4ef7\u5f88\u5927\u7684\u64cd\u4f5c\uff0c\u5bf9\u7cfb\u7edf\u6027\u80fd\u7684\u5f71\u54cd\u8fd8\u662f\u5f88\u5927\uff0c\u7279\u522b\u662f\u90a3\u4e9b\u9891\u7e41 I\/O \u7684\u573a\u666f\uff0c\u66f4\u662f\u4f1a\u56e0\u4e3a CPU \u62f7\u8d1d\u800c\u635f\u5931\u6389\u5f88\u591a\u6027\u80fd\uff0c\u6211\u4eec\u9700\u8981\u8fdb\u4e00\u6b65\u4f18\u5316\uff0c\u964d\u4f4e\u3001\u751a\u81f3\u662f\u5b8c\u5168\u907f\u514d CPU \u62f7\u8d1d\u3002<\/p>\n<h3 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u96f6\u62f7\u8d1d (Zero-copy)<\/h3>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">Zero-copy \u662f\u4ec0\u4e48\uff1f<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">Wikipedia \u7684\u89e3\u91ca\u5982\u4e0b\uff1a<\/p>\n<blockquote data-tool=\"mdnice\u7f16\u8f91\u5668\"><p>&#8220;<strong>Zero-copy<\/strong>&#8221; describes computer operations in which the\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Central_processing_unit\" data-linktype=\"2\">CPU<\/a>\u00a0does not perform the task of copying data from one\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/RAM\" data-linktype=\"2\">memory<\/a>\u00a0area to another. This is frequently used to save CPU cycles and memory bandwidth when transmitting a file over a network.<\/p><\/blockquote>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u96f6\u62f7\u8d1d\u6280\u672f\u662f\u6307\u8ba1\u7b97\u673a\u6267\u884c\u64cd\u4f5c\u65f6\uff0c<a href=\"https:\/\/zh.wikipedia.org\/wiki\/%E4%B8%AD%E5%A4%AE%E5%A4%84%E7%90%86%E5%99%A8\" data-linktype=\"2\">CPU<\/a>\u4e0d\u9700\u8981\u5148\u5c06\u6570\u636e\u4ece\u67d0\u5904<a href=\"https:\/\/zh.wikipedia.org\/wiki\/%E9%9A%8F%E6%9C%BA%E5%AD%98%E5%8F%96%E5%AD%98%E5%82%A8%E5%99%A8\" data-linktype=\"2\">\u5185\u5b58<\/a>\u590d\u5236\u5230\u53e6\u4e00\u4e2a\u7279\u5b9a\u533a\u57df\u3002\u8fd9\u79cd\u6280\u672f\u901a\u5e38\u7528\u4e8e\u901a\u8fc7\u7f51\u7edc\u4f20\u8f93\u6587\u4ef6\u65f6\u8282\u7701 CPU \u5468\u671f\u548c<a href=\"https:\/\/zh.wikipedia.org\/wiki\/%E5%86%85%E5%AD%98%E5%B8%A6%E5%AE%BD\" data-linktype=\"2\">\u5185\u5b58\u5e26\u5bbd<\/a>\u3002<\/p>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">Zero-copy \u80fd\u505a\u4ec0\u4e48\uff1f<\/h4>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u51cf\u5c11\u751a\u81f3\u5b8c\u5168\u907f\u514d\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u548c\u7528\u6237\u5e94\u7528\u7a0b\u5e8f\u5730\u5740\u7a7a\u95f4\u8fd9\u4e24\u8005\u4e4b\u95f4\u8fdb\u884c\u6570\u636e\u62f7\u8d1d\u64cd\u4f5c\uff0c\u4ece\u800c\u51cf\u5c11\u7528\u6237\u6001 &#8212; \u5185\u6838\u6001\u4e0a\u4e0b\u6587\u5207\u6362\u5e26\u6765\u7684\u7cfb\u7edf\u5f00\u9500\u3002<\/section>\n<\/li>\n<li>\n<section>\u51cf\u5c11\u751a\u81f3\u5b8c\u5168\u907f\u514d\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u7f13\u51b2\u533a\u4e4b\u95f4\u8fdb\u884c\u6570\u636e\u62f7\u8d1d\u64cd\u4f5c\u3002<\/section>\n<\/li>\n<li>\n<section>\u5e2e\u52a9\u7528\u6237\u8fdb\u7a0b\u7ed5\u5f00\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u7a7a\u95f4\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u5b58\u50a8\u63a5\u53e3\u64cd\u4f5c\u6570\u636e\u3002<\/section>\n<\/li>\n<li>\n<section>\u5229\u7528 DMA \u800c\u975e CPU \u6765\u5b8c\u6210\u786c\u4ef6\u63a5\u53e3\u548c\u5185\u6838\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u6570\u636e\u62f7\u8d1d\uff0c\u4ece\u800c\u89e3\u653e CPU\uff0c\u4f7f\u4e4b\u80fd\u53bb\u6267\u884c\u5176\u4ed6\u7684\u4efb\u52a1\uff0c\u63d0\u5347\u7cfb\u7edf\u6027\u80fd\u3002<\/section>\n<\/li>\n<\/ul>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">Zero-copy \u7684\u5b9e\u73b0\u65b9\u5f0f\u6709\u54ea\u4e9b\uff1f<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4ece zero-copy \u8fd9\u4e2a\u6982\u5ff5\u88ab\u63d0\u51fa\u4ee5\u6765\uff0c\u76f8\u5173\u7684\u5b9e\u73b0\u6280\u672f\u4fbf\u72b9\u5982\u96e8\u540e\u6625\u7b0b\uff0c\u5c42\u51fa\u4e0d\u7a77\u3002\u4f46\u662f\u622a\u81f3\u76ee\u524d\u4e3a\u6b62\uff0c\u5e76\u6ca1\u6709\u4efb\u4f55\u4e00\u79cd zero-copy \u6280\u672f\u80fd\u6ee1\u8db3\u6240\u6709\u7684\u573a\u666f\u9700\u6c42\uff0c\u8fd8\u662f\u8ba1\u7b97\u673a\u9886\u57df\u90a3\u53e5\u65e0\u6bd4\u7ecf\u5178\u7684\u540d\u8a00\uff1a&#8221;There is no silver bullet&#8221;!<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u800c\u5728 Linux \u5e73\u53f0\u4e0a\uff0c\u540c\u6837\u4e5f\u6709\u5f88\u591a\u7684 zero-copy \u6280\u672f\uff0c\u65b0\u65e7\u5404\u4e0d\u540c\uff0c\u53ef\u80fd\u5b58\u5728\u4e8e\u4e0d\u540c\u7684\u5185\u6838\u7248\u672c\u91cc\uff0c\u5f88\u591a\u6280\u672f\u53ef\u80fd\u6709\u4e86\u5f88\u5927\u7684\u6539\u8fdb\u6216\u8005\u88ab\u66f4\u65b0\u7684\u5b9e\u73b0\u65b9\u5f0f\u6240\u66ff\u4ee3\uff0c\u8fd9\u4e9b\u4e0d\u540c\u7684\u5b9e\u73b0\u6280\u672f\u6309\u7167\u5176\u6838\u5fc3\u601d\u60f3\u53ef\u4ee5\u5f52\u7eb3\u6210\u5927\u81f4\u7684\u4ee5\u4e0b\u4e09\u7c7b\uff1a<\/p>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section><strong>\u51cf\u5c11\u751a\u81f3\u907f\u514d\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684\u6570\u636e\u62f7\u8d1d<\/strong>\uff1a\u5728\u4e00\u4e9b\u573a\u666f\u4e0b\uff0c\u7528\u6237\u8fdb\u7a0b\u5728\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u5e76\u4e0d\u9700\u8981\u5bf9\u6570\u636e\u8fdb\u884c\u8bbf\u95ee\u548c\u5904\u7406\uff0c\u90a3\u4e48\u6570\u636e\u5728 Linux \u7684\u00a0<code>Page Cache<\/code>\u00a0\u548c\u7528\u6237\u8fdb\u7a0b\u7684\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u4f20\u8f93\u5c31\u5b8c\u5168\u53ef\u4ee5\u907f\u514d\uff0c\u8ba9\u6570\u636e\u62f7\u8d1d\u5b8c\u5168\u5728\u5185\u6838\u91cc\u8fdb\u884c\uff0c\u751a\u81f3\u53ef\u4ee5\u901a\u8fc7\u66f4\u5de7\u5999\u7684\u65b9\u5f0f\u907f\u514d\u5728\u5185\u6838\u91cc\u7684\u6570\u636e\u62f7\u8d1d\u3002\u8fd9\u4e00\u7c7b\u5b9e\u73b0\u4e00\u822c\u662f\u901a\u8fc7\u589e\u52a0\u65b0\u7684\u7cfb\u7edf\u8c03\u7528\u6765\u5b8c\u6210\u7684\uff0c\u6bd4\u5982 Linux \u4e2d\u7684 mmap()\uff0csendfile() \u4ee5\u53ca splice() \u7b49\u3002<\/section>\n<\/li>\n<li>\n<section><strong>\u7ed5\u8fc7\u5185\u6838\u7684\u76f4\u63a5 I\/O<\/strong>\uff1a\u5141\u8bb8\u5728\u7528\u6237\u6001\u8fdb\u7a0b\u7ed5\u8fc7\u5185\u6838\u76f4\u63a5\u548c\u786c\u4ef6\u8fdb\u884c\u6570\u636e\u4f20\u8f93\uff0c\u5185\u6838\u5728\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u53ea\u8d1f\u8d23\u4e00\u4e9b\u7ba1\u7406\u548c\u8f85\u52a9\u7684\u5de5\u4f5c\u3002\u8fd9\u79cd\u65b9\u5f0f\u5176\u5b9e\u548c\u7b2c\u4e00\u79cd\u6709\u70b9\u7c7b\u4f3c\uff0c\u4e5f\u662f\u8bd5\u56fe\u907f\u514d\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684\u6570\u636e\u4f20\u8f93\uff0c\u53ea\u662f\u7b2c\u4e00\u79cd\u65b9\u5f0f\u662f\u628a\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u653e\u5728\u5185\u6838\u6001\u5b8c\u6210\uff0c\u800c\u8fd9\u79cd\u65b9\u5f0f\u5219\u662f\u76f4\u63a5\u7ed5\u8fc7\u5185\u6838\u548c\u786c\u4ef6\u901a\u4fe1\uff0c\u6548\u679c\u7c7b\u4f3c\u4f46\u539f\u7406\u5b8c\u5168\u4e0d\u540c\u3002<\/section>\n<\/li>\n<li>\n<section><strong>\u5185\u6838\u7f13\u51b2\u533a\u548c\u7528\u6237\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u4f20\u8f93\u4f18\u5316<\/strong>\uff1a\u8fd9\u79cd\u65b9\u5f0f\u4fa7\u91cd\u4e8e\u5728\u7528\u6237\u8fdb\u7a0b\u7684\u7f13\u51b2\u533a\u548c\u64cd\u4f5c\u7cfb\u7edf\u7684\u9875\u7f13\u5b58\u4e4b\u95f4\u7684 CPU \u62f7\u8d1d\u7684\u4f18\u5316\u3002\u8fd9\u79cd\u65b9\u6cd5\u5ef6\u7eed\u4e86\u4ee5\u5f80\u90a3\u79cd\u4f20\u7edf\u7684\u901a\u4fe1\u65b9\u5f0f\uff0c\u4f46\u66f4\u7075\u6d3b\u3002<\/section>\n<\/li>\n<\/ul>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoKZFfpfFqAyEwuzPjkpEhU5Riaeejyo0iah3Mlc8zYI2Do96tHYoGWaIw\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.6196078431372549\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoKZFfpfFqAyEwuzPjkpEhU5Riaeejyo0iah3Mlc8zYI2Do96tHYoGWaIw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"2040\" data-fail=\"0\" \/><\/figure>\n<h5 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u51cf\u5c11\u751a\u81f3\u907f\u514d\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684\u6570\u636e\u62f7\u8d1d<\/h5>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">mmap()<\/h6>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>#include\u00a0&lt;sys\/mman.h&gt;\r\n\r\nvoid\u00a0*mmap(void\u00a0*addr,\u00a0size_t\u00a0length,\u00a0int\u00a0prot,\u00a0int\u00a0flags,\u00a0int\u00a0fd,\u00a0off_t\u00a0offset);\r\nint\u00a0munmap(void\u00a0*addr,\u00a0size_t\u00a0length);\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e00\u79cd\u7b80\u5355\u7684\u5b9e\u73b0\u65b9\u6848\u662f\u5728\u4e00\u6b21\u8bfb\u5199\u8fc7\u7a0b\u4e2d\u7528 Linux \u7684\u53e6\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u00a0<code>mmap()<\/code>\u00a0\u66ff\u6362\u539f\u5148\u7684\u00a0<code>read()<\/code>\uff0c<code>mmap()<\/code>\u00a0\u4e5f\u5373\u662f\u5185\u5b58\u6620\u5c04\uff08memory map\uff09\uff1a\u628a\u7528\u6237\u8fdb\u7a0b\u7a7a\u95f4\u7684\u4e00\u6bb5\u5185\u5b58\u7f13\u51b2\u533a\uff08user buffer\uff09\u6620\u5c04\u5230\u6587\u4ef6\u6240\u5728\u7684\u5185\u6838\u7f13\u51b2\u533a\uff08kernel buffer\uff09\u4e0a\u3002<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOodZctNiboBoK4g0lSb1HdhP6ic7X2f3eWx1S1yDmeRm6MtVyvmeI4Tfsw\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.57\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOodZctNiboBoK4g0lSb1HdhP6ic7X2f3eWx1S1yDmeRm6MtVyvmeI4Tfsw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5229\u7528\u00a0<code>mmap()<\/code>\u00a0\u66ff\u6362\u00a0<code>read()<\/code>\uff0c\u914d\u5408\u00a0<code>write()<\/code>\u00a0\u8c03\u7528\u7684\u6574\u4e2a\u6d41\u7a0b\u5982\u4e0b\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>mmap()<\/code>\uff0c\u4ece\u7528\u6237\u6001\u9677\u5165\u5185\u6838\u6001\uff0c\u5c06\u5185\u6838\u7f13\u51b2\u533a\u6620\u5c04\u5230\u7528\u6237\u7f13\u5b58\u533a\uff1b<\/p>\n<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u5c06\u6570\u636e\u4ece\u786c\u76d8\u62f7\u8d1d\u5230\u5185\u6838\u7f13\u51b2\u533a\uff1b<\/p>\n<\/section>\n<\/li>\n<li>\n<section><code>mmap()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u5207\u6362\u56de\u7528\u6237\u6001\uff1b<\/p>\n<\/section>\n<\/li>\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>write()<\/code>\uff0c\u5c1d\u8bd5\u628a\u6587\u4ef6\u6570\u636e\u5199\u5230\u5185\u6838\u91cc\u7684\u5957\u63a5\u5b57\u7f13\u51b2\u533a\uff0c\u518d\u6b21\u9677\u5165\u5185\u6838\u6001\uff1b<\/p>\n<\/section>\n<\/li>\n<li>\n<section>CPU \u5c06\u5185\u6838\u7f13\u51b2\u533a\u4e2d\u7684\u6570\u636e\u62f7\u8d1d\u5230\u7684\u5957\u63a5\u5b57\u7f13\u51b2\u533a\uff1b<\/p>\n<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u5c06\u6570\u636e\u4ece\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u62f7\u8d1d\u5230\u7f51\u5361\u5b8c\u6210\u6570\u636e\u4f20\u8f93\uff1b<\/p>\n<\/section>\n<\/li>\n<li>\n<section><code>write()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u5207\u6362\u56de\u7528\u6237\u6001\u3002<\/p>\n<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u901a\u8fc7\u8fd9\u79cd\u65b9\u5f0f\uff0c\u6709\u4e24\u4e2a\u4f18\u70b9\uff1a\u4e00\u662f\u8282\u7701\u5185\u5b58\u7a7a\u95f4\uff0c\u56e0\u4e3a\u7528\u6237\u8fdb\u7a0b\u4e0a\u7684\u8fd9\u4e00\u6bb5\u5185\u5b58\u662f\u865a\u62df\u7684\uff0c\u5e76\u4e0d\u771f\u6b63\u5360\u636e\u7269\u7406\u5185\u5b58\uff0c\u53ea\u662f\u6620\u5c04\u5230\u6587\u4ef6\u6240\u5728\u7684\u5185\u6838\u7f13\u51b2\u533a\u4e0a\uff0c\u56e0\u6b64\u53ef\u4ee5\u8282\u7701\u4e00\u534a\u7684\u5185\u5b58\u5360\u7528\uff1b\u4e8c\u662f\u7701\u53bb\u4e86\u4e00\u6b21 CPU \u62f7\u8d1d\uff0c\u5bf9\u6bd4\u4f20\u7edf\u7684 Linux I\/O \u8bfb\u5199\uff0c\u6570\u636e\u4e0d\u9700\u8981\u518d\u7ecf\u8fc7\u7528\u6237\u8fdb\u7a0b\u8fdb\u884c\u8f6c\u53d1\u4e86\uff0c\u800c\u662f\u76f4\u63a5\u5728\u5185\u6838\u91cc\u5c31\u5b8c\u6210\u4e86\u62f7\u8d1d\u3002\u6240\u4ee5\u4f7f\u7528\u00a0<code>mmap()<\/code>\u00a0\u4e4b\u540e\u7684\u62f7\u8d1d\u6b21\u6570\u662f 2 \u6b21 DMA \u62f7\u8d1d\uff0c1 \u6b21 CPU \u62f7\u8d1d\uff0c\u52a0\u8d77\u6765\u4e00\u5171 3 \u6b21\u62f7\u8d1d\u64cd\u4f5c\uff0c\u6bd4\u4f20\u7edf\u7684 I\/O \u65b9\u5f0f\u8282\u7701\u4e86\u4e00\u6b21 CPU \u62f7\u8d1d\u4ee5\u53ca\u4e00\u534a\u7684\u5185\u5b58\uff0c\u4e0d\u8fc7\u56e0\u4e3a\u00a0<code>mmap()<\/code>\u00a0\u4e5f\u662f\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\uff0c\u56e0\u6b64\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u5207\u6362\u8fd8\u662f 4 \u6b21\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>mmap()<\/code>\u00a0\u56e0\u4e3a\u65e2\u8282\u7701 CPU \u62f7\u8d1d\u6b21\u6570\u53c8\u8282\u7701\u5185\u5b58\uff0c\u6240\u4ee5\u6bd4\u8f83\u9002\u5408\u5927\u6587\u4ef6\u4f20\u8f93\u7684\u573a\u666f\u3002\u867d\u7136\u00a0<code>mmap()<\/code>\u00a0\u5b8c\u5168\u662f\u7b26\u5408 POSIX \u6807\u51c6\u7684\uff0c\u4f46\u662f\u5b83\u4e5f\u4e0d\u662f\u5b8c\u7f8e\u7684\uff0c\u56e0\u4e3a\u5b83\u5e76\u4e0d\u603b\u662f\u80fd\u8fbe\u5230\u7406\u60f3\u7684\u6570\u636e\u4f20\u8f93\u6027\u80fd\u3002\u9996\u5148\u662f\u56e0\u4e3a\u6570\u636e\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u4f9d\u7136\u9700\u8981\u4e00\u6b21 CPU \u62f7\u8d1d\uff0c\u5176\u6b21\u662f\u5185\u5b58\u6620\u5c04\u6280\u672f\u662f\u4e00\u4e2a\u5f00\u9500\u5f88\u5927\u7684\u865a\u62df\u5b58\u50a8\u64cd\u4f5c\uff1a\u8fd9\u79cd\u64cd\u4f5c\u9700\u8981\u4fee\u6539\u9875\u8868\u4ee5\u53ca\u7528\u5185\u6838\u7f13\u51b2\u533a\u91cc\u7684\u6587\u4ef6\u6570\u636e\u6c70\u6362\u6389\u5f53\u524d TLB \u91cc\u7684\u7f13\u5b58\u4ee5\u7ef4\u6301\u865a\u62df\u5185\u5b58\u6620\u5c04\u7684\u4e00\u81f4\u6027\u3002\u4f46\u662f\uff0c\u56e0\u4e3a\u5185\u5b58\u6620\u5c04\u901a\u5e38\u9488\u5bf9\u7684\u662f\u76f8\u5bf9\u8f83\u5927\u7684\u6570\u636e\u533a\u57df\uff0c\u6240\u4ee5\u5bf9\u4e8e\u76f8\u540c\u5927\u5c0f\u7684\u6570\u636e\u6765\u8bf4\uff0c\u5185\u5b58\u6620\u5c04\u6240\u5e26\u6765\u7684\u5f00\u9500\u8fdc\u8fdc\u4f4e\u4e8e CPU \u62f7\u8d1d\u6240\u5e26\u6765\u7684\u5f00\u9500\u3002\u6b64\u5916\uff0c\u4f7f\u7528\u00a0<code>mmap()<\/code>\u00a0\u8fd8\u53ef\u80fd\u4f1a\u9047\u5230\u4e00\u4e9b\u9700\u8981\u503c\u5f97\u5173\u6ce8\u7684\u7279\u6b8a\u60c5\u51b5\uff0c\u4f8b\u5982\uff0c\u5728\u00a0<code>mmap()<\/code>\u00a0&#8211;&gt;\u00a0<code>write()<\/code>\u00a0\u8fd9\u4e24\u4e2a\u7cfb\u7edf\u8c03\u7528\u7684\u6574\u4e2a\u4f20\u8f93\u8fc7\u7a0b\u4e2d\uff0c\u5982\u679c\u6709\u5176\u4ed6\u7684\u8fdb\u7a0b\u7a81\u7136\u622a\u65ad\u4e86\u8fd9\u4e2a\u6587\u4ef6\uff0c\u90a3\u4e48\u8fd9\u65f6\u7528\u6237\u8fdb\u7a0b\u5c31\u4f1a\u56e0\u4e3a\u8bbf\u95ee\u975e\u6cd5\u5730\u5740\u800c\u88ab\u4e00\u4e2a\u4ece\u603b\u7ebf\u4f20\u6765\u7684 SIGBUS \u4e2d\u65ad\u4fe1\u53f7\u6740\u6b7b\u5e76\u4e14\u4ea7\u751f\u4e00\u4e2a core dump\u3002\u6709\u4e24\u79cd\u89e3\u51b3\u529e\u6cd5\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u8bbe\u7f6e\u4e00\u4e2a\u4fe1\u53f7\u5904\u7406\u5668\uff0c\u4e13\u95e8\u7528\u6765\u5904\u7406 SIGBUS \u4fe1\u53f7\uff0c\u8fd9\u4e2a\u5904\u7406\u5668\u76f4\u63a5\u8fd4\u56de\uff0c\u00a0<code>write()<\/code>\u00a0\u5c31\u53ef\u4ee5\u6b63\u5e38\u8fd4\u56de\u5df2\u5199\u5165\u7684\u5b57\u8282\u6570\u800c\u4e0d\u4f1a\u88ab SIGBUS \u4e2d\u65ad\uff0cerrno \u9519\u8bef\u7801\u4e5f\u4f1a\u88ab\u8bbe\u7f6e\u6210 success\u3002\u7136\u800c\u8fd9\u5b9e\u9645\u4e0a\u662f\u4e00\u4e2a\u63a9\u8033\u76d7\u94c3\u7684\u89e3\u51b3\u65b9\u6848\uff0c\u56e0\u4e3a BIGBUS \u4fe1\u53f7\u7684\u5e26\u6765\u7684\u4fe1\u606f\u662f\u7cfb\u7edf\u53d1\u751f\u4e86\u4e00\u4e9b\u5f88\u4e25\u91cd\u7684\u9519\u8bef\uff0c\u800c\u6211\u4eec\u5374\u9009\u62e9\u5ffd\u7565\u6389\u5b83\uff0c\u4e00\u822c\u4e0d\u5efa\u8bae\u91c7\u7528\u8fd9\u79cd\u65b9\u5f0f\u3002<\/section>\n<\/li>\n<li>\n<section>\u901a\u8fc7\u5185\u6838\u7684\u6587\u4ef6\u79df\u501f\u9501\uff08\u8fd9\u662f Linux \u7684\u53eb\u6cd5\uff0cWindows \u4e0a\u79f0\u4e4b\u4e3a\u673a\u4f1a\u9501\uff09\u6765\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u8fd9\u79cd\u65b9\u6cd5\u76f8\u5bf9\u6765\u8bf4\u66f4\u597d\u4e00\u4e9b\u3002\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u5185\u6838\u5bf9\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e0a\u8bfb\/\u5199\u7684\u79df\u501f\u9501\uff0c\u5f53\u53e6\u5916\u4e00\u4e2a\u8fdb\u7a0b\u5c1d\u8bd5\u5bf9\u5f53\u524d\u7528\u6237\u8fdb\u7a0b\u6b63\u5728\u8fdb\u884c\u4f20\u8f93\u7684\u6587\u4ef6\u8fdb\u884c\u622a\u65ad\u7684\u65f6\u5019\uff0c\u5185\u6838\u4f1a\u53d1\u9001\u7ed9\u7528\u6237\u4e00\u4e2a\u5b9e\u65f6\u4fe1\u53f7\uff1aRT_SIGNAL_LEASE \u4fe1\u53f7\uff0c\u8fd9\u4e2a\u4fe1\u53f7\u4f1a\u544a\u8bc9\u7528\u6237\u5185\u6838\u6b63\u5728\u7834\u574f\u4f60\u52a0\u5728\u90a3\u4e2a\u6587\u4ef6\u4e0a\u7684\u8bfb\/\u5199\u79df\u501f\u9501\uff0c\u8fd9\u65f6\u00a0<code>write()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u4f1a\u88ab\u4e2d\u65ad\uff0c\u5e76\u4e14\u5f53\u524d\u7528\u6237\u8fdb\u7a0b\u4f1a\u88ab SIGBUS \u4fe1\u53f7\u6740\u6b7b\uff0c\u8fd4\u56de\u503c\u5219\u662f\u4e2d\u65ad\u524d\u5199\u7684\u5b57\u8282\u6570\uff0cerrno \u540c\u6837\u4f1a\u88ab\u8bbe\u7f6e\u4e3a success\u3002\u6587\u4ef6\u79df\u501f\u9501\u9700\u8981\u5728\u5bf9\u6587\u4ef6\u8fdb\u884c\u5185\u5b58\u6620\u5c04\u4e4b\u524d\u8bbe\u7f6e\uff0c\u6700\u540e\u5728\u7528\u6237\u8fdb\u7a0b\u7ed3\u675f\u4e4b\u524d\u91ca\u653e\u6389\u3002<\/section>\n<\/li>\n<\/ol>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">sendfile()<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5728 Linux \u5185\u6838 2.1 \u7248\u672c\u4e2d\uff0c\u5f15\u5165\u4e86\u4e00\u4e2a\u65b0\u7684\u7cfb\u7edf\u8c03\u7528\u00a0<code>sendfile()<\/code>\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>#include\u00a0&lt;sys\/sendfile.h&gt;\r\n\r\nssize_t\u00a0sendfile(int\u00a0out_fd,\u00a0int\u00a0in_fd,\u00a0off_t\u00a0*offset,\u00a0size_t\u00a0count);\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4ece\u529f\u80fd\u4e0a\u6765\u770b\uff0c\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u5c06\u00a0<code>mmap()<\/code>\u00a0+\u00a0<code>write()<\/code>\u00a0\u8fd9\u4e24\u4e2a\u7cfb\u7edf\u8c03\u7528\u5408\u4e8c\u4e3a\u4e00\uff0c\u5b9e\u73b0\u4e86\u4e00\u6837\u6548\u679c\u7684\u540c\u65f6\u8fd8\u7b80\u5316\u4e86\u7528\u6237\u63a5\u53e3\uff0c\u5176\u4ed6\u7684\u4e00\u4e9b Unix-like \u7684\u7cfb\u7edf\u50cf BSD\u3001Solaris \u548c AIX \u7b49\u4e5f\u6709\u7c7b\u4f3c\u7684\u5b9e\u73b0\uff0c\u751a\u81f3 Windows \u4e0a\u4e5f\u6709\u4e00\u4e2a\u529f\u80fd\u7c7b\u4f3c\u7684 API \u51fd\u6570\u00a0<code>TransmitFile<\/code>\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">out_fd \u548c in_fd \u5206\u522b\u4ee3\u8868\u4e86\u5199\u5165\u548c\u8bfb\u51fa\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0cin_fd \u5fc5\u987b\u662f\u4e00\u4e2a\u6307\u5411\u6587\u4ef6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u4e14\u8981\u80fd\u652f\u6301\u7c7b\u00a0<code>mmap()<\/code>\u00a0\u5185\u5b58\u6620\u5c04\uff0c\u4e0d\u80fd\u662f Socket \u7c7b\u578b\uff0c\u800c out_fd \u5728 Linux \u5185\u6838 2.6.33 \u7248\u672c\u4e4b\u524d\u53ea\u80fd\u662f\u4e00\u4e2a\u6307\u5411 Socket \u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u4ece 2.6.33 \u4e4b\u540e\u5219\u53ef\u4ee5\u662f\u4efb\u610f\u7c7b\u578b\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002off_t \u662f\u4e00\u4e2a\u4ee3\u8868\u4e86 in_fd \u504f\u79fb\u91cf\u7684\u6307\u9488\uff0c\u6307\u793a\u00a0<code>sendfile()<\/code>\u00a0\u8be5\u4ece in_fd \u7684\u54ea\u4e2a\u4f4d\u7f6e\u5f00\u59cb\u8bfb\u53d6\uff0c\u51fd\u6570\u8fd4\u56de\u540e\uff0c\u8fd9\u4e2a\u6307\u9488\u4f1a\u88ab\u66f4\u65b0\u6210\u00a0<code>sendfile()<\/code>\u00a0\u6700\u540e\u8bfb\u53d6\u7684\u5b57\u8282\u4f4d\u7f6e\u5904\uff0c\u8868\u660e\u6b64\u6b21\u8c03\u7528\u5171\u8bfb\u53d6\u4e86\u591a\u5c11\u6587\u4ef6\u6570\u636e\uff0c\u6700\u540e\u7684 count \u53c2\u6570\u5219\u662f\u6b64\u6b21\u8c03\u7528\u9700\u8981\u4f20\u8f93\u7684\u5b57\u8282\u603b\u6570\u3002<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoPVfUl02TQeuQ2ia8eFWDzibfAWBsVHeBMCzT5nN1j1w04WpTIfbAUtUw\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.57\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoPVfUl02TQeuQ2ia8eFWDzibfAWBsVHeBMCzT5nN1j1w04WpTIfbAUtUw\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f7f\u7528\u00a0<code>sendfile()<\/code>\u00a0\u5b8c\u6210\u4e00\u6b21\u6570\u636e\u8bfb\u5199\u7684\u6d41\u7a0b\u5982\u4e0b\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>sendfile()<\/code>\u00a0\u4ece\u7528\u6237\u6001\u9677\u5165\u5185\u6838\u6001\uff1b<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u5c06\u6570\u636e\u4ece\u786c\u76d8\u62f7\u8d1d\u5230\u5185\u6838\u7f13\u51b2\u533a\uff1b<\/section>\n<\/li>\n<li>\n<section>CPU \u5c06\u5185\u6838\u7f13\u51b2\u533a\u4e2d\u7684\u6570\u636e\u62f7\u8d1d\u5230\u5957\u63a5\u5b57\u7f13\u51b2\u533a\uff1b<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u5c06\u6570\u636e\u4ece\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u62f7\u8d1d\u5230\u7f51\u5361\u5b8c\u6210\u6570\u636e\u4f20\u8f93\uff1b<\/section>\n<\/li>\n<li>\n<section><code>sendfile()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u5207\u6362\u56de\u7528\u6237\u6001\u3002<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u57fa\u4e8e\u00a0<code>sendfile()<\/code>\uff0c \u6574\u4e2a\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u5171\u53d1\u751f 2 \u6b21 DMA \u62f7\u8d1d\u548c 1 \u6b21 CPU \u62f7\u8d1d\uff0c\u8fd9\u4e2a\u548c\u00a0<code>mmap()<\/code>\u00a0+\u00a0<code>write()<\/code>\u00a0\u76f8\u540c\uff0c\u4f46\u662f\u56e0\u4e3a\u00a0<code>sendfile()<\/code>\u00a0\u53ea\u662f\u4e00\u6b21\u7cfb\u7edf\u8c03\u7528\uff0c\u56e0\u6b64\u6bd4\u524d\u8005\u5c11\u4e86\u4e00\u6b21\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u4e0a\u4e0b\u6587\u5207\u6362\u5f00\u9500\u3002\u8bfb\u5230\u8fd9\u91cc\uff0c\u806a\u660e\u7684\u8bfb\u8005\u5e94\u8be5\u4f1a\u5f00\u59cb\u63d0\u95ee\u4e86\uff1a&#8221;<code>sendfile()<\/code>\u00a0\u4f1a\u4e0d\u4f1a\u9047\u5230\u548c\u00a0<code>mmap()<\/code>\u00a0+\u00a0<code>write()<\/code>\u00a0\u76f8\u4f3c\u7684\u6587\u4ef6\u622a\u65ad\u95ee\u9898\u5462\uff1f&#8221;\uff0c\u5f88\u4e0d\u5e78\uff0c\u7b54\u6848\u662f\u80af\u5b9a\u7684\u3002<code>sendfile()<\/code>\u00a0\u4e00\u6837\u4f1a\u6709\u6587\u4ef6\u622a\u65ad\u7684\u95ee\u9898\uff0c\u4f46\u6b23\u6170\u7684\u662f\uff0c<code>sendfile()<\/code>\u00a0\u4e0d\u4ec5\u6bd4\u00a0<code>mmap()<\/code>\u00a0+\u00a0<code>write()<\/code>\u00a0\u5728\u63a5\u53e3\u4f7f\u7528\u4e0a\u66f4\u52a0\u7b80\u6d01\uff0c\u800c\u4e14\u5904\u7406\u6587\u4ef6\u622a\u65ad\u65f6\u4e5f\u66f4\u52a0\u4f18\u96c5\uff1a\u5982\u679c\u00a0<code>sendfile()<\/code>\u00a0\u8fc7\u7a0b\u4e2d\u906d\u9047\u6587\u4ef6\u622a\u65ad\uff0c\u5219\u00a0<code>sendfile()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u4f1a\u88ab\u4e2d\u65ad\u6740\u6b7b\u4e4b\u524d\u8fd4\u56de\u7ed9\u7528\u6237\u8fdb\u7a0b\u5176\u4e2d\u65ad\u524d\u6240\u4f20\u8f93\u7684\u5b57\u8282\u6570\uff0cerrno \u4f1a\u88ab\u8bbe\u7f6e\u4e3a success\uff0c\u65e0\u9700\u7528\u6237\u63d0\u524d\u8bbe\u7f6e\u4fe1\u53f7\u5904\u7406\u5668\uff0c\u5f53\u7136\u4f60\u8981\u8bbe\u7f6e\u4e00\u4e2a\u8fdb\u884c\u4e2a\u6027\u5316\u5904\u7406\u4e5f\u53ef\u4ee5\uff0c\u4e5f\u4e0d\u9700\u8981\u50cf\u4e4b\u524d\u90a3\u6837\u63d0\u524d\u7ed9\u6587\u4ef6\u63cf\u8ff0\u7b26\u8bbe\u7f6e\u4e00\u4e2a\u79df\u501f\u9501\uff0c\u56e0\u4e3a\u6700\u7ec8\u7ed3\u679c\u8fd8\u662f\u4e00\u6837\u7684\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>sendfile()<\/code>\u00a0\u76f8\u8f83\u4e8e\u00a0<code>mmap()<\/code>\u00a0\u7684\u53e6\u4e00\u4e2a\u4f18\u52bf\u5728\u4e8e\u6570\u636e\u5728\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u59cb\u7ec8\u6ca1\u6709\u8d8a\u8fc7\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u8fb9\u754c\uff0c\u56e0\u6b64\u6781\u5927\u5730\u51cf\u5c11\u4e86\u5b58\u50a8\u7ba1\u7406\u7684\u5f00\u9500\u3002\u5373\u4fbf\u5982\u6b64\uff0c<code>sendfile()<\/code>\u00a0\u4f9d\u7136\u662f\u4e00\u4e2a\u9002\u7528\u6027\u5f88\u7a84\u7684\u6280\u672f\uff0c\u6700\u9002\u5408\u7684\u573a\u666f\u57fa\u672c\u4e5f\u5c31\u662f\u4e00\u4e2a\u9759\u6001\u6587\u4ef6\u670d\u52a1\u5668\u4e86\u3002\u800c\u4e14\u6839\u636e Linus \u5728 2001 \u5e74\u548c\u5176\u4ed6\u5185\u6838\u7ef4\u62a4\u8005\u7684\u90ae\u4ef6\u5217\u8868\u5185\u5bb9\uff0c\u5176\u5b9e\u5f53\u521d\u4e4b\u6240\u4ee5\u51b3\u5b9a\u5728 Linux \u4e0a\u5b9e\u73b0\u00a0<code>sendfile()<\/code>\u00a0\u4ec5\u4ec5\u662f\u56e0\u4e3a\u5728\u5176\u4ed6\u64cd\u4f5c\u7cfb\u7edf\u5e73\u53f0\u4e0a\u5df2\u7ecf\u7387\u5148\u5b9e\u73b0\u4e86\uff0c\u800c\u4e14\u6709\u5927\u540d\u9f0e\u9f0e\u7684 Apache Web \u670d\u52a1\u5668\u5df2\u7ecf\u5728\u4f7f\u7528\u4e86\uff0c\u4e3a\u4e86\u517c\u5bb9 Apache Web \u670d\u52a1\u5668\u624d\u51b3\u5b9a\u5728 Linux \u4e0a\u4e5f\u5b9e\u73b0\u8fd9\u4e2a\u6280\u672f\uff0c\u800c\u4e14\u00a0<code>sendfile()<\/code>\u00a0\u5b9e\u73b0\u4e0a\u7684\u7b80\u6d01\u6027\u4e5f\u548c Linux \u5185\u6838\u7684\u5176\u4ed6\u90e8\u5206\u96c6\u6210\u5f97\u5f88\u597d\uff0c\u6240\u4ee5 Linus \u4e5f\u5c31\u540c\u610f\u4e86\u8fd9\u4e2a\u63d0\u6848\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7136\u800c\u00a0<code>sendfile()<\/code>\u00a0\u672c\u8eab\u662f\u6709\u5f88\u5927\u95ee\u9898\u7684\uff0c\u4ece\u4e0d\u540c\u7684\u89d2\u5ea6\u6765\u770b\u7684\u8bdd\u4e3b\u8981\u662f\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u9996\u5148\u4e00\u4e2a\u662f\u8fd9\u4e2a\u63a5\u53e3\u5e76\u6ca1\u6709\u8fdb\u884c\u6807\u51c6\u5316\uff0c\u5bfc\u81f4\u00a0<code>sendfile()<\/code>\u00a0\u5728 Linux \u4e0a\u7684\u63a5\u53e3\u5b9e\u73b0\u548c\u5176\u4ed6\u7c7b Unix \u7cfb\u7edf\u7684\u5b9e\u73b0\u5e76\u4e0d\u76f8\u540c\uff1b<\/section>\n<\/li>\n<li>\n<section>\u5176\u6b21\u7531\u4e8e\u7f51\u7edc\u4f20\u8f93\u7684\u5f02\u6b65\u6027\uff0c\u5f88\u96be\u5728\u63a5\u6536\u7aef\u5b9e\u73b0\u548c\u00a0<code>sendfile()<\/code>\u00a0\u5bf9\u63a5\u7684\u6280\u672f\uff0c\u56e0\u6b64\u63a5\u6536\u7aef\u4e00\u76f4\u6ca1\u6709\u5b9e\u73b0\u5bf9\u5e94\u7684\u8fd9\u79cd\u6280\u672f\uff1b<\/section>\n<\/li>\n<li>\n<section>\u6700\u540e\u4ece\u6027\u80fd\u65b9\u9762\u8003\u91cf\uff0c\u56e0\u4e3a\u00a0<code>sendfile()<\/code>\u00a0\u5728\u628a\u78c1\u76d8\u6587\u4ef6\u4ece\u5185\u6838\u7f13\u51b2\u533a\uff08page cache\uff09\u4f20\u8f93\u5230\u5230\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u7684\u8fc7\u7a0b\u4e2d\u4f9d\u7136\u9700\u8981 CPU \u53c2\u4e0e\uff0c\u8fd9\u5c31\u5f88\u96be\u907f\u514d CPU \u7684\u9ad8\u901f\u7f13\u5b58\u88ab\u4f20\u8f93\u7684\u6570\u636e\u6240\u6c61\u67d3\u3002<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6b64\u5916\uff0c\u9700\u8981\u8bf4\u660e\u4e0b\uff0c<code>sendfile()<\/code>\u00a0\u7684\u6700\u521d\u8bbe\u8ba1\u5e76\u4e0d\u662f\u7528\u6765\u5904\u7406\u5927\u6587\u4ef6\u7684\uff0c\u56e0\u6b64\u5982\u679c\u9700\u8981\u5904\u7406\u5f88\u5927\u7684\u6587\u4ef6\u7684\u8bdd\uff0c\u53ef\u4ee5\u4f7f\u7528\u53e6\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u00a0<code>sendfile64()<\/code>\uff0c\u5b83\u652f\u6301\u5bf9\u66f4\u5927\u7684\u6587\u4ef6\u5185\u5bb9\u8fdb\u884c\u5bfb\u5740\u548c\u504f\u79fb\u3002<\/p>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">send\ufb01le() with DMA Scatter\/Gather Copy<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e0a\u4e00\u5c0f\u8282\u4ecb\u7ecd\u7684\u00a0<code>sendfile()<\/code>\u00a0\u6280\u672f\u5df2\u7ecf\u628a\u4e00\u6b21\u6570\u636e\u8bfb\u5199\u8fc7\u7a0b\u4e2d\u7684 CPU \u62f7\u8d1d\u7684\u964d\u4f4e\u81f3\u53ea\u6709 1 \u6b21\u4e86\uff0c\u4f46\u662f\u4eba\u6c38\u8fdc\u662f\u8d2a\u5fc3\u548c\u4e0d\u77e5\u8db3\u7684\uff0c\u73b0\u5728\u5982\u679c\u60f3\u8981\u628a\u8fd9\u4ec5\u6709\u7684\u4e00\u6b21 CPU \u62f7\u8d1d\u4e5f\u53bb\u9664\u6389\uff0c\u6709\u6ca1\u6709\u529e\u6cd5\u5462\uff1f<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5f53\u7136\u6709\uff01\u901a\u8fc7\u5f15\u5165\u4e00\u4e2a\u65b0\u786c\u4ef6\u4e0a\u7684\u652f\u6301\uff0c\u6211\u4eec\u53ef\u4ee5\u628a\u8fd9\u4e2a\u4ec5\u5269\u7684\u4e00\u6b21 CPU \u62f7\u8d1d\u4e5f\u7ed9\u62b9\u6389\uff1aLinux \u5728\u5185\u6838 2.4 \u7248\u672c\u91cc\u5f15\u5165\u4e86 DMA \u7684 scatter\/gather &#8212; \u5206\u6563\/\u6536\u96c6\u529f\u80fd\uff0c\u5e76\u4fee\u6539\u4e86\u00a0<code>sendfile()<\/code>\u00a0\u7684\u4ee3\u7801\u4f7f\u4e4b\u548c DMA \u9002\u914d\u3002scatter \u4f7f\u5f97 DMA \u62f7\u8d1d\u53ef\u4ee5\u4e0d\u518d\u9700\u8981\u628a\u6570\u636e\u5b58\u50a8\u5728\u4e00\u7247\u8fde\u7eed\u7684\u5185\u5b58\u7a7a\u95f4\u4e0a\uff0c\u800c\u662f\u5141\u8bb8\u79bb\u6563\u5b58\u50a8\uff0cgather \u5219\u80fd\u591f\u8ba9 DMA \u63a7\u5236\u5668\u6839\u636e\u5c11\u91cf\u7684\u5143\u4fe1\u606f\uff1a\u4e00\u4e2a\u5305\u542b\u4e86\u5185\u5b58\u5730\u5740\u548c\u6570\u636e\u5927\u5c0f\u7684\u7f13\u51b2\u533a\u63cf\u8ff0\u7b26\uff0c\u6536\u96c6\u5b58\u50a8\u5728\u5404\u5904\u7684\u6570\u636e\uff0c\u6700\u7ec8\u8fd8\u539f\u6210\u4e00\u4e2a\u5b8c\u6574\u7684\u7f51\u7edc\u5305\uff0c\u76f4\u63a5\u62f7\u8d1d\u5230\u7f51\u5361\u800c\u975e\u5957\u63a5\u5b57\u7f13\u51b2\u533a\uff0c\u907f\u514d\u4e86\u6700\u540e\u4e00\u6b21\u7684 CPU \u62f7\u8d1d\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoNm32yLVrNqU3bicU9aIMGkzoJib00Iz0eoOA0xDVCBIQWiaD0SMATDuJQ\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.57\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoNm32yLVrNqU3bicU9aIMGkzoJib00Iz0eoOA0xDVCBIQWiaD0SMATDuJQ\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>sendfile() + DMA gather<\/code>\u00a0\u7684\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u5982\u4e0b\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>sendfile()<\/code>\uff0c\u4ece\u7528\u6237\u6001\u9677\u5165\u5185\u6838\u6001\uff1b<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u4f7f\u7528 scatter \u529f\u80fd\u628a\u6570\u636e\u4ece\u786c\u76d8\u62f7\u8d1d\u5230\u5185\u6838\u7f13\u51b2\u533a\u8fdb\u884c\u79bb\u6563\u5b58\u50a8\uff1b<\/section>\n<\/li>\n<li>\n<section>CPU \u628a\u5305\u542b\u5185\u5b58\u5730\u5740\u548c\u6570\u636e\u957f\u5ea6\u7684\u7f13\u51b2\u533a\u63cf\u8ff0\u7b26\u62f7\u8d1d\u5230\u5957\u63a5\u5b57\u7f13\u51b2\u533a\uff0cDMA \u63a7\u5236\u5668\u80fd\u591f\u6839\u636e\u8fd9\u4e9b\u4fe1\u606f\u751f\u6210\u7f51\u7edc\u5305\u6570\u636e\u5206\u7ec4\u7684\u62a5\u5934\u548c\u62a5\u5c3e<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u6839\u636e\u7f13\u51b2\u533a\u63cf\u8ff0\u7b26\u91cc\u7684\u5185\u5b58\u5730\u5740\u548c\u6570\u636e\u5927\u5c0f\uff0c\u4f7f\u7528 scatter-gather \u529f\u80fd\u5f00\u59cb\u4ece\u5185\u6838\u7f13\u51b2\u533a\u6536\u96c6\u79bb\u6563\u7684\u6570\u636e\u5e76\u7ec4\u5305\uff0c\u6700\u540e\u76f4\u63a5\u628a\u7f51\u7edc\u5305\u6570\u636e\u62f7\u8d1d\u5230\u7f51\u5361\u5b8c\u6210\u6570\u636e\u4f20\u8f93\uff1b<\/section>\n<\/li>\n<li>\n<section><code>sendfile()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u5207\u6362\u56de\u7528\u6237\u6001\u3002<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u57fa\u4e8e\u8fd9\u79cd\u65b9\u6848\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u628a\u8fd9\u4ec5\u5269\u7684\u552f\u4e00\u4e00\u6b21 CPU \u62f7\u8d1d\u4e5f\u7ed9\u53bb\u9664\u4e86\uff08\u4e25\u683c\u6765\u8bf4\u8fd8\u662f\u4f1a\u6709\u4e00\u6b21\uff0c\u4f46\u662f\u56e0\u4e3a\u8fd9\u6b21 CPU \u62f7\u8d1d\u7684\u53ea\u662f\u90a3\u4e9b\u5fae\u4e4e\u5176\u5fae\u7684\u5143\u4fe1\u606f\uff0c\u5f00\u9500\u51e0\u4e4e\u53ef\u4ee5\u5ffd\u7565\u4e0d\u8ba1\uff09\uff0c\u7406\u8bba\u4e0a\uff0c\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u5c31\u518d\u4e5f\u6ca1\u6709 CPU \u7684\u53c2\u4e0e\u4e86\uff0c\u4e5f\u56e0\u6b64 CPU \u7684\u9ad8\u901f\u7f13\u5b58\u518d\u4e0d\u4f1a\u88ab\u6c61\u67d3\u4e86\uff0c\u4e5f\u4e0d\u518d\u9700\u8981 CPU \u6765\u8ba1\u7b97\u6570\u636e\u6821\u9a8c\u548c\u4e86\uff0cCPU \u53ef\u4ee5\u53bb\u6267\u884c\u5176\u4ed6\u7684\u4e1a\u52a1\u8ba1\u7b97\u4efb\u52a1\uff0c\u540c\u65f6\u548c DMA \u7684 I\/O \u4efb\u52a1\u5e76\u884c\uff0c\u6b64\u4e3e\u80fd\u6781\u5927\u5730\u63d0\u5347\u7cfb\u7edf\u6027\u80fd\u3002<\/p>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">splice()<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>sendfile()<\/code>\u00a0+ DMA Scatter\/Gather \u7684\u96f6\u62f7\u8d1d\u65b9\u6848\u867d\u7136\u9ad8\u6548\uff0c\u4f46\u662f\u4e5f\u6709\u4e24\u4e2a\u7f3a\u70b9\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u8fd9\u79cd\u65b9\u6848\u9700\u8981\u5f15\u5165\u65b0\u7684\u786c\u4ef6\u652f\u6301\uff1b<\/section>\n<\/li>\n<li>\n<section>\u867d\u7136\u00a0<code>sendfile()<\/code>\u00a0\u7684\u8f93\u51fa\u6587\u4ef6\u63cf\u8ff0\u7b26\u5728 Linux kernel 2.6.33 \u7248\u672c\u4e4b\u540e\u5df2\u7ecf\u53ef\u4ee5\u652f\u6301\u4efb\u610f\u7c7b\u578b\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u4f46\u662f\u8f93\u5165\u6587\u4ef6\u63cf\u8ff0\u7b26\u4f9d\u7136\u53ea\u80fd\u6307\u5411\u6587\u4ef6\u3002<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u4e24\u4e2a\u7f3a\u70b9\u9650\u5236\u4e86\u00a0<code>sendfile()<\/code>\u00a0+ DMA Scatter\/Gather \u65b9\u6848\u7684\u9002\u7528\u573a\u666f\u3002\u4e3a\u6b64\uff0cLinux \u5728 2.6.17 \u7248\u672c\u5f15\u5165\u4e86\u4e00\u4e2a\u65b0\u7684\u7cfb\u7edf\u8c03\u7528\u00a0<code>splice()<\/code>\uff0c\u5b83\u5728\u529f\u80fd\u4e0a\u548c\u00a0<code>sendfile()<\/code>\u00a0\u975e\u5e38\u76f8\u4f3c\uff0c\u4f46\u662f\u80fd\u591f\u5b9e\u73b0\u5728\u4efb\u610f\u7c7b\u578b\u7684\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u65f6\u4e4b\u95f4\u4f20\u8f93\u6570\u636e\uff1b\u800c\u5728\u5e95\u5c42\u5b9e\u73b0\u4e0a\uff0c<code>splice()<\/code>\u53c8\u6bd4\u00a0<code>sendfile()<\/code>\u00a0\u5c11\u4e86\u4e00\u6b21 CPU \u62f7\u8d1d\uff0c\u4e5f\u5c31\u662f\u7b49\u540c\u4e8e\u00a0<code>sendfile()<\/code>\u00a0+ DMA Scatter\/Gather\uff0c\u5b8c\u5168\u53bb\u9664\u4e86\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u7684 CPU \u62f7\u8d1d\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>splice()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u51fd\u6570\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>#include\u00a0&lt;fcntl.h&gt;\r\n#include\u00a0&lt;unistd.h&gt;\r\n\r\nint\u00a0pipe(int\u00a0pipefd[2]);\r\nint\u00a0pipe2(int\u00a0pipefd[2],\u00a0int\u00a0flags);\r\n\r\nssize_t\u00a0splice(int\u00a0fd_in,\u00a0loff_t\u00a0*off_in,\u00a0int\u00a0fd_out,\u00a0loff_t\u00a0*off_out,\u00a0size_t\u00a0len,\u00a0unsigned\u00a0int\u00a0flags);\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">fd_in \u548c fd_out \u4e5f\u662f\u5206\u522b\u4ee3\u8868\u4e86\u8f93\u5165\u7aef\u548c\u8f93\u51fa\u7aef\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u8fd9\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u5fc5\u987b\u6709\u4e00\u4e2a\u662f\u6307\u5411\u7ba1\u9053\u8bbe\u5907\u7684\uff0c\u8fd9\u4e5f\u662f\u4e00\u4e2a\u4e0d\u592a\u53cb\u597d\u7684\u9650\u5236\uff0c\u867d\u7136 Linux \u5185\u6838\u5f00\u53d1\u7684\u5b98\u65b9\u4ece\u8fd9\u4e2a\u7cfb\u7edf\u8c03\u7528\u63a8\u51fa\u4e4b\u65f6\u5c31\u627f\u8bfa\u672a\u6765\u53ef\u80fd\u4f1a\u91cd\u6784\u53bb\u6389\u8fd9\u4e2a\u9650\u5236\uff0c\u7136\u800c\u4ed6\u4eec\u8bb8\u4e0b\u8fd9\u4e2a\u627f\u8bfa\u4e4b\u540e\u5c31\u5982\u540c\u77f3\u6c89\u5927\u6d77\uff0c\u5982\u4eca 14 \u5e74\u8fc7\u53bb\u4e86\uff0c\u4f9d\u65e7\u6773\u65e0\u97f3\u8baf&#8230;<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">off_in \u548c off_out \u5219\u5206\u522b\u662f fd_in \u548c fd_out \u7684\u504f\u79fb\u91cf\u6307\u9488\uff0c\u6307\u793a\u5185\u6838\u4ece\u54ea\u91cc\u8bfb\u53d6\u548c\u5199\u5165\u6570\u636e\uff0clen \u5219\u6307\u793a\u4e86\u6b64\u6b21\u8c03\u7528\u5e0c\u671b\u4f20\u8f93\u7684\u5b57\u8282\u6570\uff0c\u6700\u540e\u7684 flags \u662f\u7cfb\u7edf\u8c03\u7528\u7684\u6807\u8bb0\u9009\u9879\u4f4d\u63a9\u7801\uff0c\u7528\u6765\u8bbe\u7f6e\u7cfb\u7edf\u8c03\u7528\u7684\u884c\u4e3a\u5c5e\u6027\u7684\uff0c\u7531\u4ee5\u4e0b 0 \u4e2a\u6216\u8005\u591a\u4e2a\u503c\u901a\u8fc7\u300e\u6216\u300f\u64cd\u4f5c\u7ec4\u5408\u800c\u6210\uff1a<\/p>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>SPLICE_F_MOVE\uff1a\u6307\u793a\u00a0<code>splice()<\/code>\u00a0\u5c1d\u8bd5\u4ec5\u4ec5\u662f\u79fb\u52a8\u5185\u5b58\u9875\u9762\u800c\u4e0d\u662f\u590d\u5236\uff0c\u8bbe\u7f6e\u4e86\u8fd9\u4e2a\u503c\u4e0d\u4ee3\u8868\u5c31\u4e00\u5b9a\u4e0d\u4f1a\u590d\u5236\u5185\u5b58\u9875\u9762\uff0c\u590d\u5236\u8fd8\u662f\u79fb\u52a8\u53d6\u51b3\u4e8e\u5185\u6838\u80fd\u5426\u4ece\u7ba1\u9053\u4e2d\u79fb\u52a8\u5185\u5b58\u9875\u9762\uff0c\u6216\u8005\u7ba1\u9053\u4e2d\u7684\u5185\u5b58\u9875\u9762\u662f\u5426\u662f\u5b8c\u6574\u7684\uff1b\u8fd9\u4e2a\u6807\u8bb0\u7684\u521d\u59cb\u5b9e\u73b0\u6709\u5f88\u591a bug\uff0c\u6240\u4ee5\u4ece Linux 2.6.21 \u7248\u672c\u5f00\u59cb\u5c31\u5df2\u7ecf\u65e0\u6548\u4e86\uff0c\u4f46\u8fd8\u662f\u4fdd\u7559\u4e86\u4e0b\u6765\uff0c\u56e0\u4e3a\u5728\u672a\u6765\u7684\u7248\u672c\u91cc\u53ef\u80fd\u4f1a\u91cd\u65b0\u88ab\u5b9e\u73b0\u3002<\/section>\n<\/li>\n<li>\n<section>SPLICE_F_NONBLOCK\uff1a\u6307\u793a\u00a0<code>splice()<\/code>\u00a0\u4e0d\u8981\u963b\u585e I\/O\uff0c\u4e5f\u5c31\u662f\u4f7f\u5f97\u00a0<code>splice()<\/code>\u00a0\u8c03\u7528\u6210\u4e3a\u4e00\u4e2a\u975e\u963b\u585e\u8c03\u7528\uff0c\u53ef\u4ee5\u7528\u6765\u5b9e\u73b0\u5f02\u6b65\u6570\u636e\u4f20\u8f93\uff0c\u4e0d\u8fc7\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u6570\u636e\u4f20\u8f93\u7684\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e5f\u6700\u597d\u662f\u9884\u5148\u901a\u8fc7 O_NONBLOCK \u6807\u8bb0\u6210\u975e\u963b\u585e I\/O\uff0c\u4e0d\u7136\u00a0<code>splice()<\/code>\u00a0\u8c03\u7528\u8fd8\u662f\u6709\u53ef\u80fd\u88ab\u963b\u585e\u3002<\/section>\n<\/li>\n<li>\n<section>SPLICE_F_MORE\uff1a\u901a\u77e5\u5185\u6838\u4e0b\u4e00\u4e2a\u00a0<code>splice()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u5c06\u4f1a\u6709\u66f4\u591a\u7684\u6570\u636e\u4f20\u8f93\u8fc7\u6765\uff0c\u8fd9\u4e2a\u6807\u8bb0\u5bf9\u4e8e\u8f93\u51fa\u7aef\u662f socket \u7684\u573a\u666f\u975e\u5e38\u6709\u7528\u3002<\/section>\n<\/li>\n<\/ul>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>splice()<\/code>\u00a0\u662f\u57fa\u4e8e Linux \u7684\u7ba1\u9053\u7f13\u51b2\u533a (pipe buffer) \u673a\u5236\u5b9e\u73b0\u7684\uff0c\u6240\u4ee5\u00a0<code>splice()<\/code>\u00a0\u7684\u4e24\u4e2a\u5165\u53c2\u6587\u4ef6\u63cf\u8ff0\u7b26\u624d\u8981\u6c42\u5fc5\u987b\u6709\u4e00\u4e2a\u662f\u7ba1\u9053\u8bbe\u5907\uff0c\u4e00\u4e2a\u5178\u578b\u7684\u00a0<code>splice()<\/code>\u00a0\u7528\u6cd5\u662f\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>int\u00a0pfd[2];\r\n\r\npipe(pfd);\r\n\r\nssize_t\u00a0bytes\u00a0=\u00a0splice(file_fd,\u00a0NULL,\u00a0pfd[1],\u00a0NULL,\u00a04096,\u00a0SPLICE_F_MOVE);\r\nassert(bytes\u00a0!=\u00a0-1);\r\n\r\nbytes\u00a0=\u00a0splice(pfd[0],\u00a0NULL,\u00a0socket_fd,\u00a0NULL,\u00a0bytes,\u00a0SPLICE_F_MOVE\u00a0|\u00a0SPLICE_F_MORE);\r\nassert(bytes\u00a0!=\u00a0-1);\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u56fe\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOozljDCNLQlRaRpYtu9manJZNqmB2o0dCxTZaFkNroYj6BTtpUicwVaug\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.57\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOozljDCNLQlRaRpYtu9manJZNqmB2o0dCxTZaFkNroYj6BTtpUicwVaug\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f7f\u7528\u00a0<code>splice()<\/code>\u00a0\u5b8c\u6210\u4e00\u6b21\u78c1\u76d8\u6587\u4ef6\u5230\u7f51\u5361\u7684\u8bfb\u5199\u8fc7\u7a0b\u5982\u4e0b\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>pipe()<\/code>\uff0c\u4ece\u7528\u6237\u6001\u9677\u5165\u5185\u6838\u6001\uff0c\u521b\u5efa\u533f\u540d\u5355\u5411\u7ba1\u9053\uff0c<code>pipe()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u5207\u6362\u56de\u7528\u6237\u6001\uff1b<\/section>\n<\/li>\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>splice()<\/code>\uff0c\u4ece\u7528\u6237\u6001\u9677\u5165\u5185\u6838\u6001\uff1b<\/section>\n<\/li>\n<li>\n<section>DMA \u63a7\u5236\u5668\u5c06\u6570\u636e\u4ece\u786c\u76d8\u62f7\u8d1d\u5230\u5185\u6838\u7f13\u51b2\u533a\uff0c\u4ece\u7ba1\u9053\u7684\u5199\u5165\u7aef&#8221;\u62f7\u8d1d&#8221;\u8fdb\u7ba1\u9053\uff0c<code>splice()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u56de\u5230\u7528\u6237\u6001\uff1b<\/section>\n<\/li>\n<li>\n<section>\u7528\u6237\u8fdb\u7a0b\u518d\u6b21\u8c03\u7528\u00a0<code>splice()<\/code>\uff0c\u4ece\u7528\u6237\u6001\u9677\u5165\u5185\u6838\u6001\uff1b<\/section>\n<\/li>\n<li>\n<section>\u5185\u6838\u628a\u6570\u636e\u4ece\u7ba1\u9053\u7684\u8bfb\u53d6\u7aef&#8221;\u62f7\u8d1d&#8221;\u5230\u5957\u63a5\u5b57\u7f13\u51b2\u533a\uff0cDMA \u63a7\u5236\u5668\u5c06\u6570\u636e\u4ece\u5957\u63a5\u5b57\u7f13\u51b2\u533a\u62f7\u8d1d\u5230\u7f51\u5361\uff1b<\/section>\n<\/li>\n<li>\n<section><code>splice()<\/code>\u00a0\u8fd4\u56de\uff0c\u4e0a\u4e0b\u6587\u4ece\u5185\u6838\u6001\u5207\u6362\u56de\u7528\u6237\u6001\u3002<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u76f8\u4fe1\u770b\u5b8c\u4e0a\u9762\u7684\u8bfb\u5199\u6d41\u7a0b\u4e4b\u540e\uff0c\u8bfb\u8005\u80af\u5b9a\u4f1a\u975e\u5e38\u56f0\u60d1\uff1a\u8bf4\u597d\u7684\u00a0<code>splice()<\/code>\u00a0\u662f\u00a0<code>sendfile()<\/code>\u00a0\u7684\u6539\u8fdb\u7248\u5462\uff1f<code>sendfile()<\/code>\u00a0\u597d\u6b79\u53ea\u9700\u8981\u4e00\u6b21\u7cfb\u7edf\u8c03\u7528\uff0c<code>splice()<\/code>\u00a0\u5c45\u7136\u9700\u8981\u4e09\u6b21\uff0c\u8fd9\u4e5f\u5c31\u7f62\u4e86\uff0c\u5c45\u7136\u4e2d\u95f4\u8fd8\u641e\u51fa\u6765\u4e00\u4e2a\u7ba1\u9053\uff0c\u800c\u4e14\u8fd8\u8981\u5728\u5185\u6838\u7a7a\u95f4\u62f7\u8d1d\u4e24\u6b21\uff0c\u8fd9\u7b97\u4e2a\u6bdb\u7684\u6539\u8fdb\u554a\uff1f<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6211\u6700\u5f00\u59cb\u4e86\u89e3\u00a0<code>splice()<\/code>\u00a0\u7684\u65f6\u5019\uff0c\u4e5f\u662f\u8fd9\u4e2a\u53cd\u5e94\uff0c\u4f46\u662f\u6df1\u5165\u5b66\u4e60\u5b83\u4e4b\u540e\uff0c\u624d\u6e10\u6e10\u77e5\u6653\u4e2a\u4e2d\u5965\u5999\uff0c\u4e14\u542c\u6211\u7ec6\u7ec6\u9053\u6765\uff1a<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5148\u6765\u4e86\u89e3\u4e00\u4e0b pipe buffer \u7ba1\u9053\uff0c\u7ba1\u9053\u662f Linux \u4e0a\u7528\u6765\u4f9b\u8fdb\u7a0b\u4e4b\u95f4\u901a\u4fe1\u7684\u4fe1\u9053\uff0c\u7ba1\u9053\u6709\u4e24\u4e2a\u7aef\uff1a\u5199\u5165\u7aef\u548c\u8bfb\u51fa\u7aef\uff0c\u4ece\u8fdb\u7a0b\u7684\u89c6\u89d2\u6765\u770b\uff0c\u7ba1\u9053\u8868\u73b0\u4e3a\u4e00\u4e2a FIFO \u5b57\u8282\u6d41\u73af\u5f62\u961f\u5217\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoulUOnwNbx1icHibyvh3I3IvHdU1ZoWSic54YHl9tXUSlz1dic4Ymh4HB0Q\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.5758333333333333\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoulUOnwNbx1icHibyvh3I3IvHdU1ZoWSic54YHl9tXUSlz1dic4Ymh4HB0Q\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7ba1\u9053\u672c\u8d28\u4e0a\u662f\u4e00\u4e2a\u5185\u5b58\u4e2d\u7684\u6587\u4ef6\uff0c\u4e5f\u5c31\u662f\u672c\u8d28\u4e0a\u8fd8\u662f\u57fa\u4e8e Linux \u7684 VFS\uff0c\u7528\u6237\u8fdb\u7a0b\u53ef\u4ee5\u901a\u8fc7\u00a0<code>pipe()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u521b\u5efa\u4e00\u4e2a\u533f\u540d\u7ba1\u9053\uff0c\u521b\u5efa\u5b8c\u6210\u4e4b\u540e\u4f1a\u6709\u4e24\u4e2a VFS \u7684 file \u7ed3\u6784\u4f53\u7684 inode \u5206\u522b\u6307\u5411\u5176\u5199\u5165\u7aef\u548c\u8bfb\u51fa\u7aef\uff0c\u5e76\u8fd4\u56de\u5bf9\u5e94\u7684\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u7528\u6237\u8fdb\u7a0b\u901a\u8fc7\u8fd9\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u8bfb\u5199\u7ba1\u9053\uff1b\u7ba1\u9053\u7684\u5bb9\u91cf\u5355\u4f4d\u662f\u4e00\u4e2a\u865a\u62df\u5185\u5b58\u7684\u9875\uff0c\u4e5f\u5c31\u662f 4KB\uff0c\u603b\u5927\u5c0f\u4e00\u822c\u662f 16 \u4e2a\u9875\uff0c\u57fa\u4e8e\u5176\u73af\u5f62\u7ed3\u6784\uff0c\u7ba1\u9053\u7684\u9875\u53ef\u4ee5\u5faa\u73af\u4f7f\u7528\uff0c\u63d0\u9ad8\u5185\u5b58\u5229\u7528\u7387\u3002Linux \u4e2d\u4ee5 pipe_buffer \u7ed3\u6784\u4f53\u5c01\u88c5\u7ba1\u9053\u9875\uff0cfile \u7ed3\u6784\u4f53\u91cc\u7684 inode \u5b57\u6bb5\u91cc\u4f1a\u4fdd\u5b58\u4e00\u4e2a pipe_inode_info \u7ed3\u6784\u4f53\u6307\u4ee3\u7ba1\u9053\uff0c\u5176\u4e2d\u4f1a\u4fdd\u5b58\u5f88\u591a\u8bfb\u5199\u7ba1\u9053\u65f6\u6240\u9700\u7684\u5143\u4fe1\u606f\uff0c\u73af\u5f62\u961f\u5217\u7684\u5934\u90e8\u6307\u9488\u9875\uff0c\u8bfb\u5199\u65f6\u7684\u540c\u6b65\u673a\u5236\u5982\u4e92\u65a5\u9501\u3001\u7b49\u5f85\u961f\u5217\u7b49\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>struct\u00a0pipe_buffer\u00a0{\r\n\u00a0struct\u00a0page\u00a0*page;\u00a0\/\/\u00a0\u5185\u5b58\u9875\u7ed3\u6784\r\n\u00a0unsigned\u00a0int\u00a0offset,\u00a0len;\u00a0\/\/\u00a0\u504f\u79fb\u91cf\uff0c\u957f\u5ea6\r\n\u00a0const\u00a0struct\u00a0pipe_buf_operations\u00a0*ops;\r\n\u00a0unsigned\u00a0int\u00a0flags;\r\n\u00a0unsigned\u00a0long\u00a0private;\r\n};\r\n\r\nstruct\u00a0pipe_inode_info\u00a0{\r\n\u00a0struct\u00a0mutex\u00a0mutex;\r\n\u00a0wait_queue_head_t\u00a0wait;\r\n\u00a0unsigned\u00a0int\u00a0nrbufs,\u00a0curbuf,\u00a0buffers;\r\n\u00a0unsigned\u00a0int\u00a0readers;\r\n\u00a0unsigned\u00a0int\u00a0writers;\r\n\u00a0unsigned\u00a0int\u00a0files;\r\n\u00a0unsigned\u00a0int\u00a0waiting_writers;\r\n\u00a0unsigned\u00a0int\u00a0r_counter;\r\n\u00a0unsigned\u00a0int\u00a0w_counter;\r\n\u00a0struct\u00a0page\u00a0*tmp_page;\r\n\u00a0struct\u00a0fasync_struct\u00a0*fasync_readers;\r\n\u00a0struct\u00a0fasync_struct\u00a0*fasync_writers;\r\n\u00a0struct\u00a0pipe_buffer\u00a0*bufs;\r\n\u00a0struct\u00a0user_struct\u00a0*user;\r\n};\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">pipe_buffer \u4e2d\u4fdd\u5b58\u4e86\u6570\u636e\u5728\u5185\u5b58\u4e2d\u7684\u9875\u3001\u504f\u79fb\u91cf\u548c\u957f\u5ea6\uff0c\u4ee5\u8fd9\u4e09\u4e2a\u503c\u6765\u5b9a\u4f4d\u6570\u636e\uff0c\u6ce8\u610f\u8fd9\u91cc\u7684\u9875\u4e0d\u662f\u865a\u62df\u5185\u5b58\u7684\u9875\uff0c\u800c\u7528\u7684\u662f\u7269\u7406\u5185\u5b58\u7684\u9875\u6846\uff0c\u56e0\u4e3a\u7ba1\u9053\u65f6\u8de8\u8fdb\u7a0b\u7684\u4fe1\u9053\uff0c\u56e0\u6b64\u4e0d\u80fd\u4f7f\u7528\u865a\u62df\u5185\u5b58\u6765\u8868\u793a\uff0c\u53ea\u80fd\u4f7f\u7528\u7269\u7406\u5185\u5b58\u7684\u9875\u6846\u5b9a\u4f4d\u6570\u636e\uff1b\u7ba1\u9053\u7684\u6b63\u5e38\u8bfb\u5199\u64cd\u4f5c\u662f\u901a\u8fc7 pipe_write()\/pipe_read() \u6765\u5b8c\u6210\u7684\uff0c\u901a\u8fc7\u628a\u6570\u636e\u8bfb\u53d6\/\u5199\u5165\u73af\u5f62\u961f\u5217\u7684 pipe_buffer \u6765\u5b8c\u6210\u6570\u636e\u4f20\u8f93\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>splice()<\/code>\u00a0\u662f\u57fa\u4e8e pipe buffer \u5b9e\u73b0\u7684\uff0c\u4f46\u662f\u5b83\u5728\u901a\u8fc7\u7ba1\u9053\u4f20\u8f93\u6570\u636e\u7684\u65f6\u5019\u5374\u662f\u96f6\u62f7\u8d1d\uff0c\u56e0\u4e3a\u5b83\u5728\u5199\u5165\u8bfb\u51fa\u65f6\u5e76\u6ca1\u6709\u4f7f\u7528 pipe_write()\/pipe_read() \u771f\u6b63\u5730\u5728\u7ba1\u9053\u7f13\u51b2\u533a\u5199\u5165\u8bfb\u51fa\u6570\u636e\uff0c\u800c\u662f\u901a\u8fc7\u628a\u6570\u636e\u5728\u5185\u5b58\u7f13\u51b2\u533a\u4e2d\u7684\u7269\u7406\u5185\u5b58\u9875\u6846\u6307\u9488\u3001\u504f\u79fb\u91cf\u548c\u957f\u5ea6\u8d4b\u503c\u7ed9\u524d\u6587\u63d0\u53ca\u7684 pipe_buffer \u4e2d\u5bf9\u5e94\u7684\u4e09\u4e2a\u5b57\u6bb5\u6765\u5b8c\u6210\u6570\u636e\u7684&#8221;\u62f7\u8d1d&#8221;\uff0c\u4e5f\u5c31\u662f\u5176\u5b9e\u53ea\u62f7\u8d1d\u4e86\u6570\u636e\u7684\u5185\u5b58\u5730\u5740\u7b49\u5143\u4fe1\u606f\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>splice()<\/code>\u00a0\u5728 Linux \u5185\u6838\u6e90\u7801\u4e2d\u7684\u5185\u90e8\u5b9e\u73b0\u662f\u00a0<code>do_splice()<\/code>\u00a0\u51fd\u6570\uff0c\u800c\u5199\u5165\u8bfb\u51fa\u7ba1\u9053\u5219\u5206\u522b\u662f\u901a\u8fc7\u00a0<code>do_splice_to()<\/code>\u00a0\u548c\u00a0<code>do_splice_from()<\/code>\uff0c\u8fd9\u91cc\u6211\u4eec\u91cd\u70b9\u6765\u89e3\u6790\u4e0b\u5199\u5165\u7ba1\u9053\u7684\u6e90\u7801\uff0c\u4e5f\u5c31\u662f\u00a0<code>do_splice_to()<\/code>\uff0c\u6211\u73b0\u5728\u624b\u5934\u7684 Linux \u5185\u6838\u7248\u672c\u662f v4.8.17\uff0c\u6211\u4eec\u5c31\u57fa\u4e8e\u8fd9\u4e2a\u7248\u672c\u6765\u5206\u6790\uff0c\u81f3\u4e8e\u8bfb\u51fa\u7684\u6e90\u7801\u51fd\u6570\u00a0<code>do_splice_from()<\/code>\uff0c\u539f\u7406\u662f\u76f8\u901a\u7684\uff0c\u5927\u5bb6\u4e3e\u4e00\u53cd\u4e09\u5373\u53ef\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>splice()<\/code>\u00a0\u5199\u5165\u6570\u636e\u5230\u7ba1\u9053\u7684\u8c03\u7528\u94fe\u5f0f\uff1a<code>do_splice()<\/code>\u00a0&#8211;&gt;\u00a0<code>do_splice_to()<\/code>\u00a0&#8211;&gt;\u00a0<code>splice_read()<\/code><\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>static\u00a0long\u00a0do_splice(struct\u00a0file\u00a0*in,\u00a0loff_t\u00a0__user\u00a0*off_in,\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0struct\u00a0file\u00a0*out,\u00a0loff_t\u00a0__user\u00a0*off_out,\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0size_t\u00a0len,\u00a0unsigned\u00a0int\u00a0flags)\r\n{\r\n...\r\n\r\n\u00a0\/\/\u00a0\u5224\u65ad\u662f\u5199\u51fa\u00a0fd\u00a0\u662f\u4e00\u4e2a\u7ba1\u9053\u8bbe\u5907\uff0c\u5219\u8fdb\u5165\u6570\u636e\u5199\u5165\u7684\u903b\u8f91\r\n\u00a0if\u00a0(opipe)\u00a0{\r\n\u00a0\u00a0if\u00a0(off_out)\r\n\u00a0\u00a0\u00a0return\u00a0-ESPIPE;\r\n\u00a0\u00a0if\u00a0(off_in)\u00a0{\r\n\u00a0\u00a0\u00a0if\u00a0(!(in-&gt;f_mode\u00a0&amp;\u00a0FMODE_PREAD))\r\n\u00a0\u00a0\u00a0\u00a0return\u00a0-EINVAL;\r\n\u00a0\u00a0\u00a0if\u00a0(copy_from_user(&amp;offset,\u00a0off_in,\u00a0sizeof(loff_t)))\r\n\u00a0\u00a0\u00a0\u00a0return\u00a0-EFAULT;\r\n\u00a0\u00a0}\u00a0else\u00a0{\r\n\u00a0\u00a0\u00a0offset\u00a0=\u00a0in-&gt;f_pos;\r\n\u00a0\u00a0}\r\n\r\n\u00a0\u00a0\/\/\u00a0\u8c03\u7528\u00a0do_splice_to\u00a0\u628a\u6587\u4ef6\u5185\u5bb9\u5199\u5165\u7ba1\u9053\r\n\u00a0\u00a0ret\u00a0=\u00a0do_splice_to(in,\u00a0&amp;offset,\u00a0opipe,\u00a0len,\u00a0flags);\r\n\r\n\u00a0\u00a0if\u00a0(!off_in)\r\n\u00a0\u00a0\u00a0in-&gt;f_pos\u00a0=\u00a0offset;\r\n\u00a0\u00a0else\u00a0if\u00a0(copy_to_user(off_in,\u00a0&amp;offset,\u00a0sizeof(loff_t)))\r\n\u00a0\u00a0\u00a0ret\u00a0=\u00a0-EFAULT;\r\n\r\n\u00a0\u00a0return\u00a0ret;\r\n\u00a0}\r\n\r\n\u00a0return\u00a0-EINVAL;\r\n}\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fdb\u5165\u00a0<code>do_splice_to()<\/code>\u00a0\u4e4b\u540e\uff0c\u518d\u8c03\u7528\u00a0<code>splice_read()<\/code>\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>static\u00a0long\u00a0do_splice_to(struct\u00a0file\u00a0*in,\u00a0loff_t\u00a0*ppos,\r\n\u00a0\u00a0\u00a0\u00a0struct\u00a0pipe_inode_info\u00a0*pipe,\u00a0size_t\u00a0len,\r\n\u00a0\u00a0\u00a0\u00a0unsigned\u00a0int\u00a0flags)\r\n{\r\n\u00a0ssize_t\u00a0(*splice_read)(struct\u00a0file\u00a0*,\u00a0loff_t\u00a0*,\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0struct\u00a0pipe_inode_info\u00a0*,\u00a0size_t,\u00a0unsigned\u00a0int);\r\n\u00a0int\u00a0ret;\r\n\r\n\u00a0if\u00a0(unlikely(!(in-&gt;f_mode\u00a0&amp;\u00a0FMODE_READ)))\r\n\u00a0\u00a0return\u00a0-EBADF;\r\n\r\n\u00a0ret\u00a0=\u00a0rw_verify_area(READ,\u00a0in,\u00a0ppos,\u00a0len);\r\n\u00a0if\u00a0(unlikely(ret\u00a0&lt;\u00a00))\r\n\u00a0\u00a0return\u00a0ret;\r\n\r\n\u00a0if\u00a0(unlikely(len\u00a0&gt;\u00a0MAX_RW_COUNT))\r\n\u00a0\u00a0len\u00a0=\u00a0MAX_RW_COUNT;\r\n\r\n\u00a0\/\/\u00a0\u5224\u65ad\u6587\u4ef6\u7684\u6587\u4ef6\u7684\u00a0file\u00a0\u7ed3\u6784\u4f53\u7684\u00a0f_op\u00a0\u4e2d\u6709\u6ca1\u6709\u53ef\u4f9b\u4f7f\u7528\u7684\u3001\u652f\u6301\u00a0splice\u00a0\u7684\u00a0splice_read\u00a0\u51fd\u6570\u6307\u9488\r\n\u00a0\/\/\u00a0\u56e0\u4e3a\u662f\u00a0splice()\u00a0\u8c03\u7528\uff0c\u56e0\u6b64\u5185\u6838\u4f1a\u63d0\u524d\u7ed9\u8fd9\u4e2a\u51fd\u6570\u6307\u9488\u6307\u6d3e\u4e00\u4e2a\u53ef\u7528\u7684\u51fd\u6570\r\n\u00a0if\u00a0(in-&gt;f_op-&gt;splice_read)\r\n\u00a0\u00a0splice_read\u00a0=\u00a0in-&gt;f_op-&gt;splice_read;\r\n\u00a0else\r\n\u00a0\u00a0splice_read\u00a0=\u00a0default_file_splice_read;\r\n\r\n\u00a0return\u00a0splice_read(in,\u00a0ppos,\u00a0pipe,\u00a0len,\u00a0flags);\r\n}\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>in-&gt;f_op-&gt;splice_read<\/code>\u00a0\u8fd9\u4e2a\u51fd\u6570\u6307\u9488\u6839\u636e\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u7c7b\u578b\u4e0d\u540c\u6709\u4e0d\u540c\u7684\u5b9e\u73b0\uff0c\u6bd4\u5982\u8fd9\u91cc\u7684 in \u662f\u4e00\u4e2a\u6587\u4ef6\uff0c\u56e0\u6b64\u662f\u00a0<code>generic_file_splice_read()<\/code>\uff0c\u5982\u679c\u662f socket \u7684\u8bdd\uff0c\u5219\u662f\u00a0<code>sock_splice_read()<\/code>\uff0c\u5176\u4ed6\u7684\u7c7b\u578b\u4e5f\u4f1a\u6709\u5bf9\u5e94\u7684\u5b9e\u73b0\uff0c\u603b\u4e4b\u6211\u4eec\u8fd9\u91cc\u5c06\u4f7f\u7528\u7684\u662f\u00a0<code>generic_file_splice_read()<\/code>\u00a0\u51fd\u6570\uff0c\u8fd9\u4e2a\u51fd\u6570\u4f1a\u7ee7\u7eed\u8c03\u7528\u5185\u90e8\u51fd\u6570\u00a0<code>__generic_file_splice_read<\/code>\u00a0\u5b8c\u6210\u4ee5\u4e0b\u5de5\u4f5c\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u5728 page cache \u9875\u7f13\u5b58\u91cc\u8fdb\u884c\u641c\u5bfb\uff0c\u770b\u770b\u6211\u4eec\u8981\u8bfb\u53d6\u8fd9\u4e2a\u6587\u4ef6\u5185\u5bb9\u662f\u5426\u5df2\u7ecf\u5728\u7f13\u5b58\u91cc\u4e86\uff0c\u5982\u679c\u662f\u5219\u76f4\u63a5\u7528\uff0c\u5426\u5219\u5982\u679c\u4e0d\u5b58\u5728\u6216\u8005\u53ea\u6709\u90e8\u5206\u6570\u636e\u5728\u7f13\u5b58\u4e2d\uff0c\u5219\u5206\u914d\u4e00\u4e9b\u65b0\u7684\u5185\u5b58\u9875\u5e76\u8fdb\u884c\u8bfb\u5165\u6570\u636e\u64cd\u4f5c\uff0c\u540c\u65f6\u4f1a\u589e\u52a0\u9875\u6846\u7684\u5f15\u7528\u8ba1\u6570\uff1b<\/section>\n<\/li>\n<li>\n<section>\u57fa\u4e8e\u8fd9\u4e9b\u5185\u5b58\u9875\uff0c\u521d\u59cb\u5316 splice_pipe_desc \u7ed3\u6784\uff0c\u8fd9\u4e2a\u7ed3\u6784\u4fdd\u5b58\u4f1a\u4fdd\u5b58\u6587\u4ef6\u6570\u636e\u7684\u5730\u5740\u5143\u4fe1\u606f\uff0c\u5305\u542b\u6709\u7269\u7406\u5185\u5b58\u9875\u6846\u5730\u5740\uff0c\u504f\u79fb\u3001\u6570\u636e\u957f\u5ea6\uff0c\u4e5f\u5c31\u662f pipe_buffer \u6240\u9700\u7684\u4e09\u4e2a\u5b9a\u4f4d\u6570\u636e\u7684\u503c\uff1b<\/section>\n<\/li>\n<li>\n<section>\u6700\u540e\uff0c\u8c03\u7528\u00a0<code>splice_to_pipe()<\/code>\uff0csplice_pipe_desc \u7ed3\u6784\u4f53\u5b9e\u4f8b\u662f\u51fd\u6570\u5165\u53c2\u3002<\/section>\n<\/li>\n<\/ol>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>ssize_t\u00a0splice_to_pipe(struct\u00a0pipe_inode_info\u00a0*pipe,\u00a0struct\u00a0splice_pipe_desc\u00a0*spd)\r\n{\r\n...\r\n\r\n\u00a0for\u00a0(;;)\u00a0{\r\n\u00a0\u00a0if\u00a0(!pipe-&gt;readers)\u00a0{\r\n\u00a0\u00a0\u00a0send_sig(SIGPIPE,\u00a0current,\u00a00);\r\n\u00a0\u00a0\u00a0if\u00a0(!ret)\r\n\u00a0\u00a0\u00a0\u00a0ret\u00a0=\u00a0-EPIPE;\r\n\u00a0\u00a0\u00a0break;\r\n\u00a0\u00a0}\r\n\r\n\u00a0\u00a0if\u00a0(pipe-&gt;nrbufs\u00a0&lt;\u00a0pipe-&gt;buffers)\u00a0{\r\n\u00a0\u00a0\u00a0int\u00a0newbuf\u00a0=\u00a0(pipe-&gt;curbuf\u00a0+\u00a0pipe-&gt;nrbufs)\u00a0&amp;\u00a0(pipe-&gt;buffers\u00a0-\u00a01);\r\n\u00a0\u00a0\u00a0struct\u00a0pipe_buffer\u00a0*buf\u00a0=\u00a0pipe-&gt;bufs\u00a0+\u00a0newbuf;\r\n\r\n\u00a0\u00a0\u00a0\/\/\u00a0\u5199\u5165\u6570\u636e\u5230\u7ba1\u9053\uff0c\u6ca1\u6709\u771f\u6b63\u62f7\u8d1d\u6570\u636e\uff0c\u800c\u662f\u5185\u5b58\u5730\u5740\u6307\u9488\u7684\u79fb\u52a8\uff0c\r\n\u00a0\u00a0\u00a0\/\/\u00a0\u628a\u7269\u7406\u9875\u6846\u3001\u504f\u79fb\u91cf\u548c\u6570\u636e\u957f\u5ea6\u8d4b\u503c\u7ed9\u00a0pipe_buffer\u00a0\u5b8c\u6210\u6570\u636e\u5165\u961f\u64cd\u4f5c\r\n\u00a0\u00a0\u00a0buf-&gt;page\u00a0=\u00a0spd-&gt;pages[page_nr];\r\n\u00a0\u00a0\u00a0buf-&gt;offset\u00a0=\u00a0spd-&gt;partial[page_nr].offset;\r\n\u00a0\u00a0\u00a0buf-&gt;len\u00a0=\u00a0spd-&gt;partial[page_nr].len;\r\n\u00a0\u00a0\u00a0buf-&gt;private\u00a0=\u00a0spd-&gt;partial[page_nr].private;\r\n\u00a0\u00a0\u00a0buf-&gt;ops\u00a0=\u00a0spd-&gt;ops;\r\n\u00a0\u00a0\u00a0if\u00a0(spd-&gt;flags\u00a0&amp;\u00a0SPLICE_F_GIFT)\r\n\u00a0\u00a0\u00a0\u00a0buf-&gt;flags\u00a0|=\u00a0PIPE_BUF_FLAG_GIFT;\r\n\r\n\u00a0\u00a0\u00a0pipe-&gt;nrbufs++;\r\n\u00a0\u00a0\u00a0page_nr++;\r\n\u00a0\u00a0\u00a0ret\u00a0+=\u00a0buf-&gt;len;\r\n\r\n\u00a0\u00a0\u00a0if\u00a0(pipe-&gt;files)\r\n\u00a0\u00a0\u00a0\u00a0do_wakeup\u00a0=\u00a01;\r\n\r\n\u00a0\u00a0\u00a0if\u00a0(!--spd-&gt;nr_pages)\r\n\u00a0\u00a0\u00a0\u00a0break;\r\n\u00a0\u00a0\u00a0if\u00a0(pipe-&gt;nrbufs\u00a0&lt;\u00a0pipe-&gt;buffers)\r\n\u00a0\u00a0\u00a0\u00a0continue;\r\n\r\n\u00a0\u00a0\u00a0break;\r\n\u00a0\u00a0}\r\n\r\n\u00a0...\r\n}\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u91cc\u53ef\u4ee5\u6e05\u695a\u5730\u770b\u5230\u00a0<code>splice()<\/code>\u00a0\u6240\u8c13\u7684\u5199\u5165\u6570\u636e\u5230\u7ba1\u9053\u5176\u5b9e\u5e76\u6ca1\u6709\u771f\u6b63\u5730\u62f7\u8d1d\u6570\u636e\uff0c\u800c\u662f\u73a9\u4e86\u4e2a tricky \u7684\u64cd\u4f5c\uff1a\u53ea\u8fdb\u884c\u5185\u5b58\u5730\u5740\u6307\u9488\u7684\u62f7\u8d1d\u800c\u4e0d\u771f\u6b63\u53bb\u62f7\u8d1d\u6570\u636e\u3002\u6240\u4ee5\uff0c\u6570\u636e\u00a0<code>splice()<\/code>\u00a0\u5728\u5185\u6838\u4e2d\u5e76\u6ca1\u6709\u8fdb\u884c\u771f\u6b63\u7684\u6570\u636e\u62f7\u8d1d\uff0c\u56e0\u6b64\u00a0<code>splice()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u4e5f\u662f\u96f6\u62f7\u8d1d\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd8\u6709\u4e00\u70b9\u9700\u8981\u6ce8\u610f\uff0c\u524d\u9762\u8bf4\u8fc7\u7ba1\u9053\u7684\u5bb9\u91cf\u662f 16 \u4e2a\u5185\u5b58\u9875\uff0c\u4e5f\u5c31\u662f 16 * 4KB = 64 KB\uff0c\u4e5f\u5c31\u662f\u8bf4\u4e00\u6b21\u5f80\u7ba1\u9053\u91cc\u5199\u6570\u636e\u7684\u65f6\u5019\u6700\u597d\u4e0d\u8981\u8d85\u8fc7 64 KB\uff0c\u5426\u5219\u7684\u8bdd\u4f1a\u00a0<code>splice()<\/code>\u00a0\u4f1a\u963b\u585e\u4f4f\uff0c\u9664\u975e\u5728\u521b\u5efa\u7ba1\u9053\u7684\u65f6\u5019\u4f7f\u7528\u7684\u662f\u00a0<code>pipe2()<\/code>\u00a0\u5e76\u901a\u8fc7\u4f20\u5165\u00a0<code>O_NONBLOCK<\/code>\u00a0\u5c5e\u6027\u5c06\u7ba1\u9053\u8bbe\u7f6e\u4e3a\u975e\u963b\u585e\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5373\u4f7f\u00a0<code>splice()<\/code>\u00a0\u901a\u8fc7\u5185\u5b58\u5730\u5740\u6307\u9488\u907f\u514d\u4e86\u771f\u6b63\u7684\u62f7\u8d1d\u5f00\u9500\uff0c\u4f46\u662f\u7b97\u8d77\u6765\u5b83\u8fd8\u8981\u4f7f\u7528\u989d\u5916\u7684\u7ba1\u9053\u6765\u5b8c\u6210\u6570\u636e\u4f20\u8f93\uff0c\u4e5f\u5c31\u662f\u6bd4\u00a0<code>sendfile()<\/code>\u00a0\u591a\u4e86\u4e24\u6b21\u7cfb\u7edf\u8c03\u7528\uff0c\u8fd9\u4e0d\u662f\u53c8\u589e\u52a0\u4e86\u4e0a\u4e0b\u6587\u5207\u6362\u7684\u5f00\u9500\u5417\uff1f\u4e3a\u4ec0\u4e48\u4e0d\u76f4\u63a5\u5728\u5185\u6838\u521b\u5efa\u7ba1\u9053\u5e76\u8c03\u7528\u90a3\u4e24\u6b21\u00a0<code>splice()<\/code>\uff0c\u7136\u540e\u53ea\u66b4\u9732\u7ed9\u7528\u6237\u4e00\u6b21\u7cfb\u7edf\u8c03\u7528\u5462\uff1f\u5b9e\u9645\u4e0a\u56e0\u4e3a\u00a0<code>splice()<\/code>\u00a0\u5229\u7528\u7ba1\u9053\u800c\u975e\u786c\u4ef6\u6765\u5b8c\u6210\u96f6\u62f7\u8d1d\u7684\u5b9e\u73b0\u6bd4\u00a0<code>sendfile()<\/code>\u00a0+ DMA Scatter\/Gather \u7684\u95e8\u69db\u66f4\u4f4e\uff0c\u56e0\u6b64\u540e\u6765\u7684\u00a0<code>sendfile()<\/code>\u00a0\u7684\u5e95\u5c42\u5b9e\u73b0\u5c31\u5df2\u7ecf\u66ff\u6362\u6210\u00a0<code>splice()<\/code>\u00a0\u4e86\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u81f3\u4e8e\u8bf4\u00a0<code>splice()<\/code>\u00a0\u672c\u8eab\u7684 API \u4e3a\u4ec0\u4e48\u8fd8\u662f\u8fd9\u79cd\u4f7f\u7528\u6a21\u5f0f\uff0c\u90a3\u662f\u56e0\u4e3a Linux \u5185\u6838\u5f00\u53d1\u56e2\u961f\u4e00\u76f4\u60f3\u628a\u57fa\u4e8e\u7ba1\u9053\u7684\u8fd9\u4e2a\u9650\u5236\u53bb\u6389\uff0c\u4f46\u4e0d\u77e5\u9053\u56e0\u4e3a\u4ec0\u4e48\u4e00\u76f4\u6401\u7f6e\uff0c\u6240\u4ee5\u8fd9\u4e2a API \u4e5f\u5c31\u4e00\u76f4\u6ca1\u53d8\u5316\uff0c\u53ea\u80fd\u7b49\u5185\u6838\u56e2\u961f\u54ea\u5929\u60f3\u8d77\u6765\u4e86\u8fd9\u4e00\u832c\uff0c\u7136\u540e\u91cd\u6784\u4e00\u4e0b\u4f7f\u4e4b\u4e0d\u518d\u4f9d\u8d56\u7ba1\u9053\uff0c\u5728\u90a3\u4e4b\u524d\uff0c\u4f7f\u7528\u00a0<code>splice()<\/code>\u00a0\u4f9d\u7136\u8fd8\u662f\u9700\u8981\u989d\u5916\u521b\u5efa\u7ba1\u9053\u6765\u4f5c\u4e3a\u4e2d\u95f4\u7f13\u51b2\uff0c\u5982\u679c\u4f60\u7684\u4e1a\u52a1\u573a\u666f\u5f88\u9002\u5408\u4f7f\u7528\u00a0<code>splice()<\/code>\uff0c\u4f46\u53c8\u662f\u6027\u80fd\u654f\u611f\u7684\uff0c\u4e0d\u60f3\u9891\u7e41\u5730\u521b\u5efa\u9500\u6bc1 pipe buffer \u7ba1\u9053\u7f13\u51b2\u533a\uff0c\u90a3\u4e48\u53ef\u4ee5\u53c2\u8003\u4e00\u4e0b HAProxy \u4f7f\u7528\u00a0<code>splice()<\/code>\u00a0\u65f6\u91c7\u7528\u7684\u4f18\u5316\u65b9\u6848\uff1a\u9884\u5148\u5206\u914d\u4e00\u4e2a pipe buffer pool \u7f13\u5b58\u7ba1\u9053\uff0c\u6bcf\u6b21\u8c03\u7528\u00a0<code>spclie()<\/code>\u00a0\u7684\u65f6\u5019\u53bb\u7f13\u5b58\u6c60\u91cc\u53d6\u4e00\u4e2a\u7ba1\u9053\uff0c\u7528\u5b8c\u5c31\u653e\u56de\u53bb\uff0c\u5faa\u73af\u5229\u7528\uff0c\u63d0\u5347\u6027\u80fd\u3002<\/p>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">send() with MSG_ZEROCOPY<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">Linux \u5185\u6838\u5728 2017 \u5e74\u7684 v4.14 \u7248\u672c\u63a5\u53d7\u4e86\u6765\u81ea Google \u5de5\u7a0b\u5e08 Willem de Bruijn \u5728 TCP \u7f51\u7edc\u62a5\u6587\u7684\u901a\u7528\u53d1\u9001\u63a5\u53e3\u00a0<code>send()<\/code>\u00a0\u4e2d\u5b9e\u73b0\u7684 zero-copy \u529f\u80fd (MSG_ZEROCOPY) \u7684 patch\uff0c\u901a\u8fc7\u8fd9\u4e2a\u65b0\u529f\u80fd\uff0c\u7528\u6237\u8fdb\u7a0b\u5c31\u80fd\u591f\u628a\u7528\u6237\u7f13\u51b2\u533a\u7684\u6570\u636e\u901a\u8fc7\u96f6\u62f7\u8d1d\u7684\u65b9\u5f0f\u7ecf\u8fc7\u5185\u6838\u7a7a\u95f4\u53d1\u9001\u5230\u7f51\u7edc\u5957\u63a5\u5b57\u4e2d\u53bb\uff0c\u8fd9\u4e2a\u65b0\u6280\u672f\u548c\u524d\u6587\u4ecb\u7ecd\u7684\u51e0\u79cd\u96f6\u62f7\u8d1d\u65b9\u5f0f\u76f8\u6bd4\u66f4\u52a0\u5148\u8fdb\uff0c\u56e0\u4e3a\u524d\u9762\u51e0\u79cd\u96f6\u62f7\u8d1d\u6280\u672f\u90fd\u662f\u8981\u6c42\u7528\u6237\u8fdb\u7a0b\u4e0d\u80fd\u5904\u7406\u52a0\u5de5\u6570\u636e\u800c\u662f\u76f4\u63a5\u8f6c\u53d1\u5230\u76ee\u6807\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e2d\u53bb\u7684\u3002Willem de Bruijn \u5728\u4ed6\u7684\u8bba\u6587\u91cc\u7ed9\u51fa\u7684\u538b\u6d4b\u6570\u636e\u662f\uff1a\u91c7\u7528 netperf \u5927\u5305\u53d1\u9001\u6d4b\u8bd5\uff0c\u6027\u80fd\u63d0\u5347 39%\uff0c\u800c\u7ebf\u4e0a\u73af\u5883\u7684\u6570\u636e\u53d1\u9001\u6027\u80fd\u5219\u63d0\u5347\u4e86 5%~8%\uff0c\u5b98\u65b9\u6587\u6863\u9648\u8ff0\u8bf4\u8fd9\u4e2a\u7279\u6027\u901a\u5e38\u53ea\u5728\u53d1\u9001 10KB \u5de6\u53f3\u5927\u5305\u7684\u573a\u666f\u4e0b\u624d\u4f1a\u6709\u663e\u8457\u7684\u6027\u80fd\u63d0\u5347\u3002\u4e00\u5f00\u59cb\u8fd9\u4e2a\u7279\u6027\u53ea\u652f\u6301 TCP\uff0c\u5230\u5185\u6838 v5.0 \u7248\u672c\u4e4b\u540e\u624d\u652f\u6301 UDP\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u4e2a\u529f\u80fd\u7684\u4f7f\u7528\u6a21\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>if\u00a0(setsockopt(socket_fd,\u00a0SOL_SOCKET,\u00a0SO_ZEROCOPY,\u00a0&amp;one,\u00a0sizeof(one)))\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0error(1,\u00a0errno,\u00a0\"setsockopt\u00a0zerocopy\");\r\n\r\nret\u00a0=\u00a0send(socket_fd,\u00a0buffer,\u00a0sizeof(buffer),\u00a0MSG_ZEROCOPY);\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u9996\u5148\u7b2c\u4e00\u6b65\uff0c\u5148\u7ed9\u8981\u53d1\u9001\u6570\u636e\u7684 socket \u8bbe\u7f6e\u4e00\u4e2a SOCK_ZEROCOPY option\uff0c\u7136\u540e\u5728\u8c03\u7528\u00a0<code>send()<\/code>\u00a0\u53d1\u9001\u6570\u636e\u65f6\u518d\u8bbe\u7f6e\u4e00\u4e2a MSG_ZEROCOPY option\uff0c\u5176\u5b9e\u7406\u8bba\u4e0a\u6765\u8bf4\u53ea\u9700\u8981\u8c03\u7528\u00a0<code>setsockopt()<\/code>\u00a0\u6216\u8005\u00a0<code>send()<\/code>\u00a0\u65f6\u4f20\u9012\u8fd9\u4e2a zero-copy \u7684 option \u5373\u53ef\uff0c\u4e24\u8005\u9009\u5176\u4e00\uff0c\u4f46\u662f\u8fd9\u91cc\u5374\u8981\u8bbe\u7f6e\u540c\u4e00\u4e2a option \u4e24\u6b21\uff0c\u5b98\u65b9\u7684\u8bf4\u6cd5\u662f\u4e3a\u4e86\u517c\u5bb9\u00a0<code>send()<\/code>\u00a0API \u4ee5\u524d\u7684\u8bbe\u8ba1\u4e0a\u7684\u4e00\u4e2a\u9519\u8bef\uff1a<code>send()<\/code>\u00a0\u4ee5\u524d\u7684\u5b9e\u73b0\u4f1a\u5ffd\u7565\u6389\u672a\u77e5\u7684 option\uff0c\u4e3a\u4e86\u517c\u5bb9\u90a3\u4e9b\u53ef\u80fd\u5df2\u7ecf\u4e0d\u5c0f\u5fc3\u8bbe\u7f6e\u4e86 MSG_ZEROCOPY option \u7684\u7a0b\u5e8f\uff0c\u6545\u800c\u8bbe\u8ba1\u6210\u4e86\u4e24\u6b65\u8bbe\u7f6e\u3002\u4e0d\u8fc7\u6211\u731c\u8fd8\u6709\u4e00\u79cd\u53ef\u80fd\uff1a\u5c31\u662f\u7ed9\u4f7f\u7528\u8005\u63d0\u4f9b\u66f4\u7075\u6d3b\u7684\u4f7f\u7528\u6a21\u5f0f\uff0c\u56e0\u4e3a\u8fd9\u4e2a\u65b0\u529f\u80fd\u53ea\u5728\u5927\u5305\u573a\u666f\u4e0b\u624d\u53ef\u80fd\u4f1a\u6709\u663e\u8457\u7684\u6027\u80fd\u63d0\u5347\uff0c\u4f46\u662f\u73b0\u5b9e\u573a\u666f\u662f\u5f88\u590d\u6742\u7684\uff0c\u4e0d\u4ec5\u4ec5\u662f\u5168\u90e8\u5927\u5305\u6216\u8005\u5168\u90e8\u5c0f\u5305\u7684\u573a\u666f\uff0c\u6709\u53ef\u80fd\u662f\u5927\u5305\u5c0f\u5305\u6df7\u5408\u7684\u573a\u666f\uff0c\u56e0\u6b64\u4f7f\u7528\u8005\u53ef\u4ee5\u5148\u8c03\u7528\u00a0<code>setsockopt()<\/code>\u00a0\u8bbe\u7f6e SOCK_ZEROCOPY option\uff0c\u7136\u540e\u518d\u6839\u636e\u5b9e\u9645\u4e1a\u52a1\u573a\u666f\u4e2d\u7684\u7f51\u7edc\u5305\u5c3a\u5bf8\u9009\u62e9\u662f\u5426\u8981\u5728\u8c03\u7528\u00a0<code>send()<\/code>\u00a0\u65f6\u4f7f\u7528 MSG_ZEROCOPY \u8fdb\u884c zero-copy \u4f20\u8f93\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u56e0\u4e3a\u00a0<code>send()<\/code>\u00a0\u53ef\u80fd\u662f\u5f02\u6b65\u53d1\u9001\u6570\u636e\uff0c\u56e0\u6b64\u4f7f\u7528 MSG_ZEROCOPY \u6709\u4e00\u4e2a\u9700\u8981\u7279\u522b\u6ce8\u610f\u7684\u70b9\u662f\uff1a\u8c03\u7528\u00a0<code>send()<\/code>\u00a0\u4e4b\u540e\u4e0d\u80fd\u7acb\u523b\u91cd\u7528\u6216\u91ca\u653e buffer\uff0c\u56e0\u4e3a buffer \u4e2d\u7684\u6570\u636e\u4e0d\u4e00\u5b9a\u5df2\u7ecf\u88ab\u5185\u6838\u8bfb\u8d70\u4e86\uff0c\u6240\u4ee5\u8fd8\u9700\u8981\u4ece socket \u5173\u8054\u7684\u9519\u8bef\u961f\u5217\u91cc\u8bfb\u53d6\u4e00\u4e0b\u901a\u77e5\u6d88\u606f\uff0c\u770b\u770b buffer \u4e2d\u7684\u6570\u636e\u662f\u5426\u5df2\u7ecf\u88ab\u5185\u6838\u8bfb\u8d70\u4e86\uff1a<\/p>\n<pre data-tool=\"mdnice\u7f16\u8f91\u5668\"><code>pfd.fd\u00a0=\u00a0fd;\r\npfd.events\u00a0=\u00a00;\r\nif\u00a0(poll(&amp;pfd,\u00a01,\u00a0-1)\u00a0!=\u00a01\u00a0||\u00a0pfd.revents\u00a0&amp;\u00a0POLLERR\u00a0==\u00a00)\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0error(1,\u00a0errno,\u00a0\"poll\");\r\n\r\nret\u00a0=\u00a0recvmsg(fd,\u00a0&amp;msg,\u00a0MSG_ERRQUEUE);\r\nif\u00a0(ret\u00a0==\u00a0-1)\r\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0error(1,\u00a0errno,\u00a0\"recvmsg\");\r\n\r\nread_notification(msg);\r\n\r\n\r\nuint32_t\u00a0read_notification(struct\u00a0msghdr\u00a0*msg)\r\n{\r\n\u00a0struct\u00a0sock_extended_err\u00a0*serr;\r\n\u00a0struct\u00a0cmsghdr\u00a0*cm;\r\n\r\n\u00a0cm\u00a0=\u00a0CMSG_FIRSTHDR(msg);\r\n\u00a0if\u00a0(cm-&gt;cmsg_level\u00a0!=\u00a0SOL_IP\u00a0&amp;&amp;\r\n\u00a0\u00a0cm-&gt;cmsg_type\u00a0!=\u00a0IP_RECVERR)\r\n\u00a0\u00a0\u00a0error(1,\u00a00,\u00a0\"cmsg\");\r\n\r\n\u00a0serr\u00a0=\u00a0(void\u00a0*)\u00a0CMSG_DATA(cm);\r\n\u00a0if\u00a0(serr-&gt;ee_errno\u00a0!=\u00a00\u00a0||\r\n\u00a0\u00a0serr-&gt;ee_origin\u00a0!=\u00a0SO_EE_ORIGIN_ZEROCOPY)\r\n\u00a0\u00a0\u00a0error(1,\u00a00,\u00a0\"serr\");\r\n\r\n\u00a0return\u00a0serr-&gt;ee\u00a0_\u00a0data;\r\n}\r\n<\/code><\/pre>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u4e2a\u6280\u672f\u662f\u57fa\u4e8e redhat \u7ea2\u5e3d\u5728 2010 \u5e74\u7ed9 Linux \u5185\u6838\u63d0\u4ea4\u7684 virtio-net zero-copy \u6280\u672f\u4e4b\u4e0a\u5b9e\u73b0\u7684\uff0c\u81f3\u4e8e\u5e95\u5c42\u539f\u7406\uff0c\u7b80\u5355\u6765\u8bf4\u5c31\u662f\u901a\u8fc7\u00a0<code>send()<\/code>\u00a0\u628a\u6570\u636e\u5728\u7528\u6237\u7f13\u51b2\u533a\u4e2d\u7684\u5206\u6bb5\u6307\u9488\u53d1\u9001\u5230 socket \u4e2d\u53bb\uff0c\u5229\u7528 page pinning \u9875\u9501\u5b9a\u673a\u5236\u9501\u4f4f\u7528\u6237\u7f13\u51b2\u533a\u7684\u5185\u5b58\u9875\uff0c\u7136\u540e\u5229\u7528 DMA \u76f4\u63a5\u5728\u7528\u6237\u7f13\u51b2\u533a\u901a\u8fc7\u5185\u5b58\u5730\u5740\u6307\u9488\u8fdb\u884c\u6570\u636e\u8bfb\u53d6\uff0c\u5b9e\u73b0\u96f6\u62f7\u8d1d\uff1b\u5177\u4f53\u7684\u7ec6\u8282\u53ef\u4ee5\u901a\u8fc7\u9605\u8bfb Willem de Bruijn \u7684<a href=\"https:\/\/netdevconf.org\/2.1\/papers\/netdev.pdf\" data-linktype=\"2\">\u8bba\u6587 (PDF)<\/a>\u00a0\u6df1\u5165\u4e86\u89e3\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u76ee\u524d\u6765\u8bf4\uff0c\u8fd9\u79cd\u6280\u672f\u7684\u4e3b\u8981\u7f3a\u9677\u6709\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u53ea\u9002\u7528\u4e8e\u5927\u6587\u4ef6 (10KB \u5de6\u53f3) \u7684\u573a\u666f\uff0c\u5c0f\u6587\u4ef6\u573a\u666f\u56e0\u4e3a page pinning \u9875\u9501\u5b9a\u548c\u7b49\u5f85\u7f13\u51b2\u533a\u91ca\u653e\u7684\u901a\u77e5\u6d88\u606f\u8fd9\u4e9b\u673a\u5236\uff0c\u751a\u81f3\u53ef\u80fd\u6bd4\u76f4\u63a5 CPU \u62f7\u8d1d\u66f4\u8017\u65f6\uff1b<\/section>\n<\/li>\n<li>\n<section>\u56e0\u4e3a\u53ef\u80fd\u5f02\u6b65\u53d1\u9001\u6570\u636e\uff0c\u9700\u8981\u989d\u5916\u8c03\u7528\u00a0<code>poll()<\/code>\u00a0\u548c\u00a0<code>recvmsg()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u7b49\u5f85 buffer \u88ab\u91ca\u653e\u7684\u901a\u77e5\u6d88\u606f\uff0c\u589e\u52a0\u4ee3\u7801\u590d\u6742\u5ea6\uff0c\u4ee5\u53ca\u4f1a\u5bfc\u81f4\u591a\u6b21\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684\u4e0a\u4e0b\u6587\u5207\u6362\uff1b<\/section>\n<\/li>\n<li>\n<section>MSG_ZEROCOPY \u76ee\u524d\u53ea\u652f\u6301\u53d1\u9001\u7aef\uff0c\u63a5\u6536\u7aef\u6682\u4e0d\u652f\u6301\u3002<\/section>\n<\/li>\n<\/ol>\n<h5 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7ed5\u8fc7\u5185\u6838\u7684\u76f4\u63a5 I\/O<\/h5>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u53ef\u4ee5\u770b\u51fa\uff0c\u524d\u9762\u79cd\u79cd\u7684 zero-copy \u7684\u65b9\u6cd5\uff0c\u90fd\u662f\u5728\u60f3\u65b9\u8bbe\u6cd5\u5730\u4f18\u5316\u51cf\u5c11\u6216\u8005\u53bb\u6389\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u4e4b\u95f4\u4ee5\u53ca\u5185\u6838\u6001\u548c\u5185\u6838\u6001\u4e4b\u95f4\u7684\u6570\u636e\u62f7\u8d1d\uff0c\u4e3a\u4e86\u5b9e\u73b0\u907f\u514d\u8fd9\u4e9b\u62f7\u8d1d\u53ef\u8c13\u662f\u516b\u4ed9\u8fc7\u6d77\uff0c\u5404\u663e\u795e\u901a\uff0c\u91c7\u7528\u4e86\u5404\u79cd\u5404\u6837\u7684\u624b\u6bb5\uff0c\u90a3\u4e48\u5982\u679c\u6211\u4eec\u6362\u4e2a\u601d\u8def\uff1a\u5176\u5b9e\u8fd9\u4e48\u8d39\u52b2\u5730\u53bb\u6d88\u9664\u8fd9\u4e9b\u62f7\u8d1d\u4e0d\u5c31\u662f\u56e0\u4e3a\u6709\u5185\u6838\u5728\u63ba\u548c\u5417\uff1f\u5982\u679c\u6211\u4eec\u7ed5\u8fc7\u5185\u6838\u76f4\u63a5\u8fdb\u884c I\/O \u4e0d\u5c31\u6ca1\u6709\u8fd9\u4e9b\u70e6\u4eba\u7684\u62f7\u8d1d\u95ee\u9898\u4e86\u5417\uff1f\u8fd9\u5c31\u662f<strong>\u7ed5\u8fc7\u5185\u6838\u76f4\u63a5 I\/O<\/strong>\u00a0\u6280\u672f\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoSpB0EuVpzAsUc3XFZl9DFogBTG3YFRKP0JW6YXG1ib9avp2x44TFdMQ\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.57\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoSpB0EuVpzAsUc3XFZl9DFogBTG3YFRKP0JW6YXG1ib9avp2x44TFdMQ\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u79cd\u65b9\u6848\u6709\u4e24\u79cd\u5b9e\u73b0\u65b9\u5f0f\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u7528\u6237\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6<\/section>\n<\/li>\n<li>\n<section>\u5185\u6838\u63a7\u5236\u8bbf\u95ee\u786c\u4ef6<\/section>\n<\/li>\n<\/ol>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7528\u6237\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u79cd\u6280\u672f\u8d4b\u4e88\u7528\u6237\u8fdb\u7a0b\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u8bbe\u5907\u7684\u6743\u9650\uff0c\u8fd9\u8ba9\u7528\u6237\u8fdb\u7a0b\u80fd\u6709\u76f4\u63a5\u8bfb\u5199\u786c\u4ef6\u8bbe\u5907\uff0c\u5728\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u53ea\u9700\u8981\u5185\u6838\u505a\u4e00\u4e9b\u865a\u62df\u5185\u5b58\u914d\u7f6e\u76f8\u5173\u7684\u5de5\u4f5c\u3002\u8fd9\u79cd\u65e0\u9700\u6570\u636e\u62f7\u8d1d\u548c\u5185\u6838\u5e72\u9884\u7684\u76f4\u63a5 I\/O\uff0c\u7406\u8bba\u4e0a\u662f\u6700\u9ad8\u6548\u7684\u6570\u636e\u4f20\u8f93\u6280\u672f\uff0c\u4f46\u662f\u6b63\u5982\u524d\u9762\u6240\u8bf4\u7684\u90a3\u6837\uff0c\u5e76\u4e0d\u5b58\u5728\u80fd\u89e3\u51b3\u4e00\u5207\u95ee\u9898\u7684\u94f6\u5f39\uff0c\u8fd9\u79cd\u76f4\u63a5 I\/O \u6280\u672f\u867d\u7136\u6709\u53ef\u80fd\u975e\u5e38\u9ad8\u6548\uff0c\u4f46\u662f\u5b83\u7684\u9002\u7528\u6027\u4e5f\u975e\u5e38\u7a84\uff0c\u76ee\u524d\u53ea\u9002\u7528\u4e8e\u8bf8\u5982 MPI \u9ad8\u6027\u80fd\u901a\u4fe1\u3001\u4e1b\u96c6\u8ba1\u7b97\u7cfb\u7edf\u4e2d\u7684\u8fdc\u7a0b\u5171\u4eab\u5185\u5b58\u7b49\u6709\u9650\u7684\u573a\u666f\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u79cd\u6280\u672f\u5b9e\u9645\u4e0a\u7834\u574f\u4e86\u73b0\u4ee3\u8ba1\u7b97\u673a\u64cd\u4f5c\u7cfb\u7edf\u6700\u91cd\u8981\u7684\u6982\u5ff5\u4e4b\u4e00 \u2014\u2014 \u786c\u4ef6\u62bd\u8c61\uff0c\u6211\u4eec\u4e4b\u524d\u63d0\u8fc7\uff0c\u62bd\u8c61\u662f\u8ba1\u7b97\u673a\u9886\u57df\u6700\u6700\u6838\u5fc3\u7684\u8bbe\u8ba1\u601d\u8def\uff0c\u6b63\u5f0f\u7531\u4e8e\u6709\u4e86\u62bd\u8c61\u548c\u5206\u5c42\uff0c\u5404\u4e2a\u5c42\u7ea7\u624d\u80fd\u4e0d\u5fc5\u53bb\u5173\u5fc3\u5f88\u591a\u5e95\u5c42\u7ec6\u8282\u4ece\u800c\u4e13\u6ce8\u4e8e\u771f\u6b63\u7684\u5de5\u4f5c\uff0c\u624d\u4f7f\u5f97\u7cfb\u7edf\u7684\u8fd0\u4f5c\u66f4\u52a0\u9ad8\u6548\u548c\u5feb\u901f\u3002\u6b64\u5916\uff0c\u7f51\u5361\u901a\u5e38\u4f7f\u7528\u529f\u80fd\u8f83\u5f31\u7684 CPU\uff0c\u4f8b\u5982\u53ea\u5305\u542b\u7b80\u5355\u6307\u4ee4\u96c6\u7684 MIPS \u67b6\u6784\u5904\u7406\u5668\uff08\u6ca1\u6709\u4e0d\u5fc5\u8981\u7684\u529f\u80fd\uff0c\u5982\u6d6e\u70b9\u6570\u8ba1\u7b97\u7b49\uff09\uff0c\u4e5f\u6ca1\u6709\u592a\u591a\u7684\u5185\u5b58\u6765\u5bb9\u7eb3\u590d\u6742\u7684\u8f6f\u4ef6\u3002\u56e0\u6b64\uff0c\u901a\u5e38\u53ea\u6709\u90a3\u4e9b\u57fa\u4e8e\u4ee5\u592a\u7f51\u4e4b\u4e0a\u7684\u4e13\u7528\u534f\u8bae\u4f1a\u4f7f\u7528\u8fd9\u79cd\u6280\u672f\uff0c\u8fd9\u4e9b\u4e13\u7528\u534f\u8bae\u7684\u8bbe\u8ba1\u8981\u6bd4\u8fdc\u6bd4 TCP\/IP \u7b80\u5355\u5f97\u591a\uff0c\u800c\u4e14\u591a\u7528\u4e8e\u5c40\u57df\u7f51\u73af\u5883\u4e2d\uff0c\u5728\u8fd9\u79cd\u73af\u5883\u4e2d\uff0c\u6570\u636e\u5305\u4e22\u5931\u548c\u635f\u574f\u5f88\u5c11\u53d1\u751f\uff0c\u56e0\u6b64\u6ca1\u6709\u5fc5\u8981\u8fdb\u884c\u590d\u6742\u7684\u6570\u636e\u5305\u786e\u8ba4\u548c\u6d41\u91cf\u63a7\u5236\u673a\u5236\u3002\u800c\u4e14\u8fd9\u79cd\u6280\u672f\u8fd8\u9700\u8981\u5b9a\u5236\u7684\u7f51\u5361\uff0c\u6240\u4ee5\u5b83\u662f\u9ad8\u5ea6\u4f9d\u8d56\u786c\u4ef6\u7684\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e0e\u4f20\u7edf\u7684\u901a\u4fe1\u8bbe\u8ba1\u76f8\u6bd4\uff0c\u76f4\u63a5\u786c\u4ef6\u8bbf\u95ee\u6280\u672f\u7ed9\u7a0b\u5e8f\u8bbe\u8ba1\u5e26\u6765\u4e86\u5404\u79cd\u9650\u5236\uff1a\u7531\u4e8e\u8bbe\u5907\u4e4b\u95f4\u7684\u6570\u636e\u4f20\u8f93\u662f\u901a\u8fc7 DMA \u5b8c\u6210\u7684\uff0c\u56e0\u6b64\u7528\u6237\u7a7a\u95f4\u7684\u6570\u636e\u7f13\u51b2\u533a\u5185\u5b58\u9875\u5fc5\u987b\u8fdb\u884c page pinning\uff08\u9875\u9501\u5b9a\uff09\uff0c\u8fd9\u662f\u4e3a\u4e86\u9632\u6b62\u5176\u7269\u7406\u9875\u6846\u5730\u5740\u88ab\u4ea4\u6362\u5230\u78c1\u76d8\u6216\u8005\u88ab\u79fb\u52a8\u5230\u65b0\u7684\u5730\u5740\u800c\u5bfc\u81f4 DMA \u53bb\u62f7\u8d1d\u6570\u636e\u7684\u65f6\u5019\u5728\u6307\u5b9a\u7684\u5730\u5740\u627e\u4e0d\u5230\u5185\u5b58\u9875\u4ece\u800c\u5f15\u53d1\u7f3a\u9875\u9519\u8bef\uff0c\u800c\u9875\u9501\u5b9a\u7684\u5f00\u9500\u5e76\u4e0d\u6bd4 CPU \u62f7\u8d1d\u5c0f\uff0c\u6240\u4ee5\u4e3a\u4e86\u907f\u514d\u9891\u7e41\u7684\u9875\u9501\u5b9a\u7cfb\u7edf\u8c03\u7528\uff0c\u5e94\u7528\u7a0b\u5e8f\u5fc5\u987b\u5206\u914d\u548c\u6ce8\u518c\u4e00\u4e2a\u6301\u4e45\u7684\u5185\u5b58\u6c60\uff0c\u7528\u4e8e\u6570\u636e\u7f13\u51b2\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7528\u6237\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u7684\u6280\u672f\u53ef\u4ee5\u5f97\u5230\u6781\u9ad8\u7684 I\/O \u6027\u80fd\uff0c\u4f46\u662f\u5176\u5e94\u7528\u9886\u57df\u548c\u9002\u7528\u573a\u666f\u4e5f\u6781\u5176\u7684\u6709\u9650\uff0c\u5982\u96c6\u7fa4\u6216\u7f51\u7edc\u5b58\u50a8\u7cfb\u7edf\u4e2d\u7684\u8282\u70b9\u901a\u4fe1\u3002\u5b83\u9700\u8981\u5b9a\u5236\u7684\u786c\u4ef6\u548c\u4e13\u95e8\u8bbe\u8ba1\u7684\u5e94\u7528\u7a0b\u5e8f\uff0c\u4f46\u76f8\u5e94\u5730\u5bf9\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u7684\u6539\u52a8\u6bd4\u8f83\u5c0f\uff0c\u53ef\u4ee5\u5f88\u5bb9\u6613\u5730\u4ee5\u5185\u6838\u6a21\u5757\u6216\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u7684\u5f62\u5f0f\u5b9e\u73b0\u51fa\u6765\u3002\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u8fd8\u53ef\u80fd\u4f1a\u5e26\u6765\u4e25\u91cd\u7684\u5b89\u5168\u95ee\u9898\uff0c\u56e0\u4e3a\u7528\u6237\u8fdb\u7a0b\u62e5\u6709\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u7684\u6781\u9ad8\u6743\u9650\uff0c\u6240\u4ee5\u5982\u679c\u4f60\u7684\u7a0b\u5e8f\u8bbe\u8ba1\u6ca1\u6709\u505a\u597d\u7684\u8bdd\uff0c\u53ef\u80fd\u4f1a\u6d88\u8017\u672c\u6765\u5c31\u6709\u9650\u7684\u786c\u4ef6\u8d44\u6e90\u6216\u8005\u8fdb\u884c\u975e\u6cd5\u5730\u5740\u8bbf\u95ee\uff0c\u53ef\u80fd\u4e5f\u4f1a\u56e0\u6b64\u95f4\u63a5\u5730\u5f71\u54cd\u5176\u4ed6\u6b63\u5728\u4f7f\u7528\u540c\u4e00\u8bbe\u5907\u7684\u5e94\u7528\u7a0b\u5e8f\uff0c\u800c\u56e0\u4e3a\u7ed5\u5f00\u4e86\u5185\u6838\uff0c\u6240\u4ee5\u4e5f\u65e0\u6cd5\u8ba9\u5185\u6838\u66ff\u4f60\u53bb\u63a7\u5236\u548c\u7ba1\u7406\u3002<\/p>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5185\u6838\u63a7\u5236\u8bbf\u95ee\u786c\u4ef6<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u76f8\u8f83\u4e8e\u7528\u6237\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u6280\u672f\uff0c\u901a\u8fc7\u5185\u6838\u63a7\u5236\u7684\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u6280\u672f\u66f4\u52a0\u7684\u5b89\u5168\uff0c\u5b83\u6bd4\u524d\u8005\u5728\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u4f1a\u591a\u5e72\u9884\u4e00\u70b9\uff0c\u4f46\u4e5f\u4ec5\u4ec5\u662f\u4f5c\u4e3a\u4e00\u4e2a\u4ee3\u7406\u4eba\u8fd9\u6837\u7684\u89d2\u8272\uff0c\u4e0d\u4f1a\u53c2\u4e0e\u5230\u5b9e\u9645\u7684\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\uff0c\u5185\u6838\u4f1a\u63a7\u5236 DMA \u5f15\u64ce\u53bb\u66ff\u7528\u6237\u8fdb\u7a0b\u505a\u7f13\u51b2\u533a\u7684\u6570\u636e\u4f20\u8f93\u5de5\u4f5c\u3002\u540c\u6837\u7684\uff0c\u8fd9\u79cd\u65b9\u5f0f\u4e5f\u662f\u9ad8\u5ea6\u4f9d\u8d56\u786c\u4ef6\u7684\uff0c\u6bd4\u5982\u4e00\u4e9b\u96c6\u6210\u4e86\u4e13\u6709\u7f51\u7edc\u6808\u534f\u8bae\u7684\u7f51\u5361\u3002\u8fd9\u79cd\u6280\u672f\u7684\u4e00\u4e2a\u4f18\u52bf\u5c31\u662f\u7528\u6237\u96c6\u6210\u53bb I\/O \u65f6\u7684\u63a5\u53e3\u4e0d\u4f1a\u6539\u53d8\uff0c\u5c31\u548c\u666e\u901a\u7684\u00a0<code>read()\/write()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u90a3\u6837\u4f7f\u7528\u5373\u53ef\uff0c\u6240\u6709\u7684\u810f\u6d3b\u7d2f\u6d3b\u90fd\u5728\u5185\u6838\u91cc\u5b8c\u6210\uff0c\u7528\u6237\u63a5\u53e3\u53cb\u597d\u5ea6\u5f88\u9ad8\uff0c\u4e0d\u8fc7\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u4f7f\u7528\u8fd9\u79cd\u6280\u672f\u7684\u8fc7\u7a0b\u4e2d\u5982\u679c\u53d1\u751f\u4e86\u4ec0\u4e48\u4e0d\u53ef\u9884\u77e5\u7684\u610f\u5916\u4ece\u800c\u5bfc\u81f4\u65e0\u6cd5\u4f7f\u7528\u8fd9\u79cd\u6280\u672f\u8fdb\u884c\u6570\u636e\u4f20\u8f93\u7684\u8bdd\uff0c\u5219\u5185\u6838\u4f1a\u81ea\u52a8\u5207\u6362\u4e3a\u6700\u4f20\u7edf I\/O \u6a21\u5f0f\uff0c\u4e5f\u5c31\u662f\u6027\u80fd\u6700\u5dee\u7684\u90a3\u79cd\u6a21\u5f0f\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u8fd9\u79cd\u6280\u672f\u4e5f\u6709\u7740\u548c\u7528\u6237\u76f4\u63a5\u8bbf\u95ee\u786c\u4ef6\u6280\u672f\u4e00\u6837\u7684\u95ee\u9898\uff1aDMA \u4f20\u8f93\u6570\u636e\u7684\u8fc7\u7a0b\u4e2d\uff0c\u7528\u6237\u8fdb\u7a0b\u7684\u7f13\u51b2\u533a\u5185\u5b58\u9875\u5fc5\u987b\u8fdb\u884c page pinning \u9875\u9501\u5b9a\uff0c\u6570\u636e\u4f20\u8f93\u5b8c\u6210\u540e\u624d\u80fd\u89e3\u9501\u3002CPU \u9ad8\u901f\u7f13\u5b58\u5185\u4fdd\u5b58\u7684\u591a\u4e2a\u5185\u5b58\u5730\u5740\u4e5f\u4f1a\u88ab\u51b2\u5237\u6389\u4ee5\u4fdd\u8bc1 DMA \u4f20\u8f93\u524d\u540e\u7684\u6570\u636e\u4e00\u81f4\u6027\u3002\u8fd9\u4e9b\u673a\u5236\u6709\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6570\u636e\u4f20\u8f93\u7684\u6027\u80fd\u53d8\u5f97\u66f4\u5dee\uff0c\u56e0\u4e3a\u00a0<code>read()\/write()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u7684\u8bed\u4e49\u5e76\u4e0d\u80fd\u63d0\u524d\u901a\u77e5 CPU \u7528\u6237\u7f13\u51b2\u533a\u8981\u53c2\u4e0e DMA \u6570\u636e\u4f20\u8f93\u4f20\u8f93\uff0c\u56e0\u6b64\u4e5f\u5c31\u65e0\u6cd5\u50cf\u5185\u6838\u7f13\u51b2\u533a\u90a3\u6837\u53ef\u4f9d\u63d0\u524d\u52a0\u8f7d\u8fdb\u9ad8\u901f\u7f13\u5b58\uff0c\u63d0\u9ad8\u6027\u80fd\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7531\u4e8e\u7528\u6237\u7f13\u51b2\u533a\u7684\u5185\u5b58\u9875\u53ef\u80fd\u5206\u5e03\u5728\u7269\u7406\u5185\u5b58\u4e2d\u7684\u4efb\u610f\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4e00\u4e9b\u5b9e\u73b0\u4e0d\u597d\u7684 DMA \u63a7\u5236\u5668\u5f15\u64ce\u53ef\u80fd\u4f1a\u6709\u5bfb\u5740\u9650\u5236\u4ece\u800c\u5bfc\u81f4\u65e0\u6cd5\u8bbf\u95ee\u8fd9\u4e9b\u5185\u5b58\u533a\u57df\u3002\u4e00\u4e9b\u6280\u672f\u6bd4\u5982 AMD64 \u67b6\u6784\u4e2d\u7684 IOMMU\uff0c\u5141\u8bb8\u901a\u8fc7\u5c06 DMA \u5730\u5740\u91cd\u65b0\u6620\u5c04\u5230\u5185\u5b58\u4e2d\u7684\u7269\u7406\u5730\u5740\u6765\u89e3\u51b3\u8fd9\u4e9b\u9650\u5236\uff0c\u4f46\u53cd\u8fc7\u6765\u53c8\u53ef\u80fd\u4f1a\u5bfc\u81f4\u53ef\u79fb\u690d\u6027\u95ee\u9898\uff0c\u56e0\u4e3a\u5176\u4ed6\u7684\u5904\u7406\u5668\u67b6\u6784\uff0c\u751a\u81f3\u662f Intel 64 \u4f4d x86 \u67b6\u6784\u7684\u53d8\u79cd EM64T \u90fd\u4e0d\u5177\u5907\u8fd9\u6837\u7684\u7279\u6027\u5355\u5143\u3002\u6b64\u5916\uff0c\u8fd8\u53ef\u80fd\u5b58\u5728\u5176\u4ed6\u9650\u5236\uff0c\u6bd4\u5982 DMA \u4f20\u8f93\u7684\u6570\u636e\u5bf9\u9f50\u95ee\u9898\uff0c\u53c8\u4f1a\u5bfc\u81f4\u65e0\u6cd5\u8bbf\u95ee\u7528\u6237\u8fdb\u7a0b\u6307\u5b9a\u7684\u4efb\u610f\u7f13\u51b2\u533a\u5185\u5b58\u5730\u5740\u3002<\/p>\n<h4 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5185\u6838\u7f13\u51b2\u533a\u548c\u7528\u6237\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u4f20\u8f93\u4f18\u5316<\/h4>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\u6211\u4eec\u8ba8\u8bba\u7684 zero-copy \u6280\u672f\u90fd\u662f\u57fa\u4e8e\u51cf\u5c11\u751a\u81f3\u662f\u907f\u514d\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684 CPU \u6570\u636e\u62f7\u8d1d\u7684\uff0c\u867d\u7136\u6709\u4e00\u4e9b\u6280\u672f\u975e\u5e38\u9ad8\u6548\uff0c\u4f46\u662f\u5927\u591a\u90fd\u6709\u9002\u7528\u6027\u5f88\u7a84\u7684\u95ee\u9898\uff0c\u6bd4\u5982\u00a0<code>sendfile()<\/code>\u3001<code>splice()<\/code>\u00a0\u8fd9\u4e9b\uff0c\u6548\u7387\u5f88\u9ad8\uff0c\u4f46\u662f\u90fd\u53ea\u9002\u7528\u4e8e\u90a3\u4e9b\u7528\u6237\u8fdb\u7a0b\u4e0d\u9700\u8981\u76f4\u63a5\u5904\u7406\u6570\u636e\u7684\u573a\u666f\uff0c\u6bd4\u5982\u9759\u6001\u6587\u4ef6\u670d\u52a1\u5668\u6216\u8005\u662f\u76f4\u63a5\u8f6c\u53d1\u6570\u636e\u7684\u4ee3\u7406\u670d\u52a1\u5668\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u73b0\u5728\u6211\u4eec\u5df2\u7ecf\u77e5\u9053\uff0c\u786c\u4ef6\u8bbe\u5907\u4e4b\u95f4\u7684\u6570\u636e\u53ef\u4ee5\u901a\u8fc7 DMA \u8fdb\u884c\u4f20\u8f93\uff0c\u7136\u800c\u5374\u5e76\u6ca1\u6709\u8fd9\u6837\u7684\u4f20\u8f93\u673a\u5236\u53ef\u4ee5\u5e94\u7528\u4e8e\u7528\u6237\u7f13\u51b2\u533a\u548c\u5185\u6838\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u6570\u636e\u4f20\u8f93\u3002\u4e0d\u8fc7\u53e6\u4e00\u65b9\u9762\uff0c\u5e7f\u6cdb\u5e94\u7528\u5728\u73b0\u4ee3\u7684 CPU \u67b6\u6784\u548c\u64cd\u4f5c\u7cfb\u7edf\u4e0a\u7684\u865a\u62df\u5185\u5b58\u673a\u5236\u8868\u660e\uff0c\u901a\u8fc7\u5728\u4e0d\u540c\u7684\u865a\u62df\u5730\u5740\u4e0a\u91cd\u65b0\u6620\u5c04\u9875\u9762\u53ef\u4ee5\u5b9e\u73b0\u5728\u7528\u6237\u8fdb\u7a0b\u548c\u5185\u6838\u4e4b\u95f4\u865a\u62df\u590d\u5236\u548c\u5171\u4eab\u5185\u5b58\uff0c\u5c3d\u7ba1\u4e00\u6b21\u4f20\u8f93\u7684\u5185\u5b58\u9897\u7c92\u5ea6\u76f8\u5bf9\u8f83\u5927\uff1a4KB \u6216 8KB\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u56e0\u6b64\u5982\u679c\u8981\u5728\u5b9e\u73b0\u5728\u7528\u6237\u8fdb\u7a0b\u5185\u5904\u7406\u6570\u636e\uff08\u8fd9\u79cd\u573a\u666f\u6bd4\u76f4\u63a5\u8f6c\u53d1\u6570\u636e\u66f4\u52a0\u5e38\u89c1\uff09\u4e4b\u540e\u518d\u53d1\u9001\u51fa\u53bb\u7684\u8bdd\uff0c\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u7684\u6570\u636e\u4f20\u8f93\u5c31\u662f\u4e0d\u53ef\u907f\u514d\u7684\uff0c\u65e2\u7136\u907f\u65e0\u53ef\u907f\uff0c\u90a3\u5c31\u53ea\u80fd\u9009\u62e9\u4f18\u5316\u4e86\uff0c\u56e0\u6b64\u672c\u7ae0\u8282\u6211\u4eec\u8981\u4ecb\u7ecd\u4e24\u79cd\u4f18\u5316\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u6570\u636e\u4f20\u8f93\u7684\u6280\u672f\uff1a<\/p>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u52a8\u6001\u91cd\u6620\u5c04\u4e0e\u5199\u65f6\u62f7\u8d1d (Copy-on-Write)<\/section>\n<\/li>\n<li>\n<section>\u7f13\u51b2\u533a\u5171\u4eab (Buffer Sharing)<\/section>\n<\/li>\n<\/ol>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u52a8\u6001\u91cd\u6620\u5c04\u4e0e\u5199\u65f6\u62f7\u8d1d (Copy-on-Write)<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u524d\u9762\u6211\u4eec\u4ecb\u7ecd\u8fc7\u5229\u7528\u5185\u5b58\u6620\u5c04\u6280\u672f\u6765\u51cf\u5c11\u6570\u636e\u5728\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684\u590d\u5236\uff0c\u901a\u5e38\u7b80\u5355\u6a21\u5f0f\u4e0b\uff0c\u7528\u6237\u8fdb\u7a0b\u662f\u5bf9\u5171\u4eab\u7684\u7f13\u51b2\u533a\u8fdb\u884c\u540c\u6b65\u963b\u585e\u8bfb\u5199\u7684\uff0c\u8fd9\u6837\u4e0d\u4f1a\u6709 data race \u95ee\u9898\uff0c\u4f46\u662f\u8fd9\u79cd\u6a21\u5f0f\u4e0b\u6548\u7387\u5e76\u4e0d\u9ad8\uff0c\u800c\u63d0\u5347\u6548\u7387\u7684\u4e00\u79cd\u65b9\u6cd5\u5c31\u662f\u5f02\u6b65\u5730\u5bf9\u5171\u4eab\u7f13\u51b2\u533a\u8fdb\u884c\u8bfb\u5199\uff0c\u800c\u8fd9\u6837\u7684\u8bdd\u5c31\u5fc5\u987b\u5f15\u5165\u4fdd\u62a4\u673a\u5236\u6765\u907f\u514d\u6570\u636e\u51b2\u7a81\u95ee\u9898\uff0c\u5199\u65f6\u590d\u5236 (Copy on Write) \u5c31\u662f\u8fd9\u6837\u7684\u4e00\u79cd\u6280\u672f\u3002<\/p>\n<blockquote data-tool=\"mdnice\u7f16\u8f91\u5668\"><p><strong>\u5199\u5165\u65f6\u590d\u5236<\/strong>\uff08<strong>Copy-on-write<\/strong>\uff0c<strong>COW<\/strong>\uff09\u662f\u4e00\u79cd\u8ba1\u7b97\u673a<a href=\"https:\/\/zh.wikipedia.org\/wiki\/%E7%A8%8B%E5%BC%8F%E8%A8%AD%E8%A8%88\" data-linktype=\"2\">\u7a0b\u5e8f\u8bbe\u8ba1<\/a>\u9886\u57df\u7684\u4f18\u5316\u7b56\u7565\u3002\u5176\u6838\u5fc3\u601d\u60f3\u662f\uff0c\u5982\u679c\u6709\u591a\u4e2a\u8c03\u7528\u8005\uff08callers\uff09\u540c\u65f6\u8bf7\u6c42\u76f8\u540c\u8d44\u6e90\uff08\u5982\u5185\u5b58\u6216\u78c1\u76d8\u4e0a\u7684\u6570\u636e\u5b58\u50a8\uff09\uff0c\u4ed6\u4eec\u4f1a\u5171\u540c\u83b7\u53d6\u76f8\u540c\u7684\u6307\u9488\u6307\u5411\u76f8\u540c\u7684\u8d44\u6e90\uff0c\u76f4\u5230\u67d0\u4e2a\u8c03\u7528\u8005\u8bd5\u56fe\u4fee\u6539\u8d44\u6e90\u7684\u5185\u5bb9\u65f6\uff0c\u7cfb\u7edf\u624d\u4f1a\u771f\u6b63\u590d\u5236\u4e00\u4efd\u4e13\u7528\u526f\u672c\uff08private copy\uff09\u7ed9\u8be5\u8c03\u7528\u8005\uff0c\u800c\u5176\u4ed6\u8c03\u7528\u8005\u6240\u89c1\u5230\u7684\u6700\u521d\u7684\u8d44\u6e90\u4ecd\u7136\u4fdd\u6301\u4e0d\u53d8\u3002\u8fd9\u8fc7\u7a0b\u5bf9\u5176\u4ed6\u7684\u8c03\u7528\u8005\u90fd\u662f<a href=\"https:\/\/zh.wikipedia.org\/wiki\/%E9%80%8F%E6%98%8E\" data-linktype=\"2\">\u900f\u660e<\/a>\u7684\u3002\u6b64\u4f5c\u6cd5\u4e3b\u8981\u7684\u4f18\u70b9\u662f\u5982\u679c\u8c03\u7528\u8005\u6ca1\u6709\u4fee\u6539\u8be5\u8d44\u6e90\uff0c\u5c31\u4e0d\u4f1a\u6709\u526f\u672c\uff08private copy\uff09\u88ab\u521b\u5efa\uff0c\u56e0\u6b64\u591a\u4e2a\u8c03\u7528\u8005\u53ea\u662f\u8bfb\u53d6\u64cd\u4f5c\u65f6\u53ef\u4ee5\u5171\u4eab\u540c\u4e00\u4efd\u8d44\u6e90\u3002<\/p><\/blockquote>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e3e\u4e00\u4e2a\u4f8b\u5b50\uff0c\u5f15\u5165\u4e86 COW \u6280\u672f\u4e4b\u540e\uff0c\u7528\u6237\u8fdb\u7a0b\u8bfb\u53d6\u78c1\u76d8\u6587\u4ef6\u8fdb\u884c\u6570\u636e\u5904\u7406\u6700\u540e\u5199\u5230\u7f51\u5361\uff0c\u9996\u5148\u4f7f\u7528\u5185\u5b58\u6620\u5c04\u6280\u672f\u8ba9\u7528\u6237\u7f13\u51b2\u533a\u548c\u5185\u6838\u7f13\u51b2\u533a\u5171\u4eab\u4e86\u4e00\u6bb5\u5185\u5b58\u5730\u5740\u5e76\u6807\u8bb0\u4e3a\u53ea\u8bfb (read-only)\uff0c\u907f\u514d\u6570\u636e\u62f7\u8d1d\uff0c\u800c\u5f53\u8981\u628a\u6570\u636e\u5199\u5230\u7f51\u5361\u7684\u65f6\u5019\uff0c\u7528\u6237\u8fdb\u7a0b\u9009\u62e9\u4e86\u5f02\u6b65\u5199\u7684\u65b9\u5f0f\uff0c\u7cfb\u7edf\u8c03\u7528\u4f1a\u76f4\u63a5\u8fd4\u56de\uff0c\u6570\u636e\u4f20\u8f93\u5c31\u4f1a\u5728\u5185\u6838\u91cc\u5f02\u6b65\u8fdb\u884c\uff0c\u800c\u7528\u6237\u8fdb\u7a0b\u5c31\u53ef\u4ee5\u7ee7\u7eed\u5176\u4ed6\u7684\u5de5\u4f5c\uff0c\u5e76\u4e14\u5171\u4eab\u7f13\u51b2\u533a\u7684\u5185\u5bb9\u53ef\u4ee5\u968f\u65f6\u518d\u8fdb\u884c\u8bfb\u53d6\uff0c\u6548\u7387\u5f88\u9ad8\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f46\u662f\u5982\u679c\u8be5\u8fdb\u7a0b\u53c8\u5c1d\u8bd5\u5f80\u5171\u4eab\u7f13\u51b2\u533a\u5199\u5165\u6570\u636e\uff0c\u5219\u4f1a\u4ea7\u751f\u4e00\u4e2a COW \u4e8b\u4ef6\uff0c\u8ba9\u8bd5\u56fe\u5199\u5165\u6570\u636e\u7684\u8fdb\u7a0b\u628a\u6570\u636e\u590d\u5236\u5230\u81ea\u5df1\u7684\u7f13\u51b2\u533a\u53bb\u4fee\u6539\uff0c\u8fd9\u91cc\u53ea\u9700\u8981\u590d\u5236\u8981\u4fee\u6539\u7684\u5185\u5b58\u9875\u5373\u53ef\uff0c\u65e0\u9700\u6240\u6709\u6570\u636e\u90fd\u590d\u5236\u8fc7\u53bb\uff0c\u800c\u5982\u679c\u5176\u4ed6\u8bbf\u95ee\u8be5\u5171\u4eab\u5185\u5b58\u7684\u8fdb\u7a0b\u4e0d\u9700\u8981\u4fee\u6539\u6570\u636e\u5219\u53ef\u4ee5\u6c38\u8fdc\u4e0d\u9700\u8981\u8fdb\u884c\u6570\u636e\u62f7\u8d1d\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">COW \u662f\u4e00\u79cd\u5efa\u6784\u5728\u865a\u62df\u5185\u5b58\u51b2\u6620\u5c04\u6280\u672f\u4e4b\u4e0a\u7684\u6280\u672f\uff0c\u56e0\u6b64\u5b83\u9700\u8981 MMU \u7684\u786c\u4ef6\u652f\u6301\uff0cMMU \u4f1a\u8bb0\u5f55\u5f53\u524d\u54ea\u4e9b\u5185\u5b58\u9875\u88ab\u6807\u8bb0\u6210\u53ea\u8bfb\uff0c\u5f53\u6709\u8fdb\u7a0b\u5c1d\u8bd5\u5f80\u8fd9\u4e9b\u5185\u5b58\u9875\u4e2d\u5199\u6570\u636e\u7684\u65f6\u5019\uff0cMMU \u5c31\u4f1a\u629b\u4e00\u4e2a\u5f02\u5e38\u7ed9\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\uff0c\u5185\u6838\u5904\u7406\u8be5\u5f02\u5e38\u65f6\u4e3a\u8be5\u8fdb\u7a0b\u5206\u914d\u4e00\u4efd\u7269\u7406\u5185\u5b58\u5e76\u590d\u5236\u6570\u636e\u5230\u6b64\u5185\u5b58\u5730\u5740\uff0c\u91cd\u65b0\u5411 MMU \u53d1\u51fa\u6267\u884c\u8be5\u8fdb\u7a0b\u7684\u5199\u64cd\u4f5c\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">COW \u6700\u5927\u7684\u4f18\u52bf\u662f\u8282\u7701\u5185\u5b58\u548c\u51cf\u5c11\u6570\u636e\u62f7\u8d1d\uff0c\u4e0d\u8fc7\u5374\u662f\u901a\u8fc7\u589e\u52a0\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838 I\/O \u8fc7\u7a0b\u590d\u6742\u6027\u4f5c\u4e3a\u4ee3\u4ef7\u7684\u3002\u5f53\u786e\u5b9a\u91c7\u7528 COW \u6765\u590d\u5236\u9875\u9762\u65f6\uff0c\u91cd\u8981\u7684\u662f\u6ce8\u610f\u7a7a\u95f2\u9875\u9762\u7684\u5206\u914d\u4f4d\u7f6e\u3002\u8bb8\u591a\u64cd\u4f5c\u7cfb\u7edf\u4e3a\u8fd9\u7c7b\u8bf7\u6c42\u63d0\u4f9b\u4e86\u4e00\u4e2a\u7a7a\u95f2\u7684\u9875\u9762\u6c60\u3002\u5f53\u8fdb\u7a0b\u7684\u5806\u6808\u6216\u5806\u8981\u6269\u5c55\u65f6\u6216\u6709\u5199\u65f6\u590d\u5236\u9875\u9762\u9700\u8981\u7ba1\u7406\u65f6\uff0c\u901a\u5e38\u5206\u914d\u8fd9\u4e9b\u7a7a\u95f2\u9875\u9762\u3002\u64cd\u4f5c\u7cfb\u7edf\u5206\u914d\u8fd9\u4e9b\u9875\u9762\u901a\u5e38\u91c7\u7528\u79f0\u4e3a<strong>\u6309\u9700\u586b\u96f6<\/strong>\u7684\u6280\u672f\u3002\u6309\u9700\u586b\u96f6\u9875\u9762\u5728\u9700\u8981\u5206\u914d\u4e4b\u524d\u5148\u586b\u96f6\uff0c\u56e0\u6b64\u4f1a\u6e05\u9664\u91cc\u9762\u65e7\u7684\u5185\u5bb9\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><strong>\u5c40\u9650\u6027<\/strong>\uff1a<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">COW \u8fd9\u79cd\u96f6\u62f7\u8d1d\u6280\u672f\u6bd4\u8f83\u9002\u7528\u4e8e\u90a3\u79cd\u591a\u8bfb\u5c11\u5199\u4ece\u800c\u4f7f\u5f97 COW \u4e8b\u4ef6\u53d1\u751f\u8f83\u5c11\u7684\u573a\u666f\uff0c\u56e0\u4e3a COW \u4e8b\u4ef6\u6240\u5e26\u6765\u7684\u7cfb\u7edf\u5f00\u9500\u8981\u8fdc\u8fdc\u9ad8\u4e8e\u4e00\u6b21 CPU \u62f7\u8d1d\u6240\u4ea7\u751f\u7684\u3002\u6b64\u5916\uff0c\u5728\u5b9e\u9645\u5e94\u7528\u7684\u8fc7\u7a0b\u4e2d\uff0c\u4e3a\u4e86\u907f\u514d\u9891\u7e41\u7684\u5185\u5b58\u6620\u5c04\uff0c\u53ef\u4ee5\u91cd\u590d\u4f7f\u7528\u540c\u4e00\u6bb5\u5185\u5b58\u7f13\u51b2\u533a\uff0c\u56e0\u6b64\uff0c\u4f60\u4e0d\u9700\u8981\u5728\u53ea\u7528\u8fc7\u4e00\u6b21\u5171\u4eab\u7f13\u51b2\u533a\u4e4b\u540e\u5c31\u89e3\u9664\u6389\u5185\u5b58\u9875\u7684\u6620\u5c04\u5173\u7cfb\uff0c\u800c\u662f\u91cd\u590d\u5faa\u73af\u4f7f\u7528\uff0c\u4ece\u800c\u63d0\u5347\u6027\u80fd\uff0c\u4e0d\u8fc7\u8fd9\u79cd\u5185\u5b58\u9875\u6620\u5c04\u7684\u6301\u4e45\u5316\u5e76\u4e0d\u4f1a\u51cf\u5c11\u7531\u4e8e\u9875\u8868\u5f80\u8fd4\u79fb\u52a8\u548c TLB \u51b2\u5237\u6240\u5e26\u6765\u7684\u7cfb\u7edf\u5f00\u9500\uff0c\u56e0\u4e3a\u6bcf\u6b21\u63a5\u6536\u5230 COW \u4e8b\u4ef6\u4e4b\u540e\u5bf9\u5185\u5b58\u9875\u800c\u8fdb\u884c\u52a0\u9501\u6216\u8005\u89e3\u9501\u7684\u65f6\u5019\uff0c\u9875\u9762\u7684\u53ea\u8bfb\u6807\u5fd7 (read-ony) \u90fd\u8981\u88ab\u66f4\u6539\u4e3a (write-only)\u3002<\/p>\n<h6 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u7f13\u51b2\u533a\u5171\u4eab (Buffer Sharing)<\/h6>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4ece\u524d\u9762\u7684\u4ecb\u7ecd\u53ef\u4ee5\u770b\u51fa\uff0c\u4f20\u7edf\u7684 Linux I\/O \u63a5\u53e3\uff0c\u90fd\u662f\u57fa\u4e8e\u590d\u5236\/\u62f7\u8d1d\u7684\uff1a\u6570\u636e\u9700\u8981\u5728\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u7a7a\u95f4\u548c\u7528\u6237\u7a7a\u95f4\u7684\u7f13\u51b2\u533a\u4e4b\u95f4\u8fdb\u884c\u62f7\u8d1d\u3002\u5728\u8fdb\u884c I\/O \u64cd\u4f5c\u4e4b\u524d\uff0c\u7528\u6237\u8fdb\u7a0b\u9700\u8981\u9884\u5148\u5206\u914d\u597d\u4e00\u4e2a\u5185\u5b58\u7f13\u51b2\u533a\uff0c\u4f7f\u7528\u00a0<code>read()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u65f6\uff0c\u5185\u6838\u4f1a\u5c06\u4ece\u5b58\u50a8\u5668\u6216\u8005\u7f51\u5361\u7b49\u8bbe\u5907\u8bfb\u5165\u7684\u6570\u636e\u62f7\u8d1d\u5230\u8fd9\u4e2a\u7528\u6237\u7f13\u51b2\u533a\u91cc\uff1b\u800c\u4f7f\u7528\u00a0<code>write()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u65f6\uff0c\u5219\u662f\u628a\u7528\u6237\u5185\u5b58\u7f13\u51b2\u533a\u7684\u6570\u636e\u62f7\u8d1d\u81f3\u5185\u6838\u7f13\u51b2\u533a\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e3a\u4e86\u5b9e\u73b0\u8fd9\u79cd\u4f20\u7edf\u7684 I\/O \u6a21\u5f0f\uff0cLinux \u5fc5\u987b\u8981\u5728\u6bcf\u4e00\u4e2a I\/O \u64cd\u4f5c\u65f6\u90fd\u8fdb\u884c\u5185\u5b58\u865a\u62df\u6620\u5c04\u548c\u89e3\u9664\u3002\u8fd9\u79cd\u5185\u5b58\u9875\u91cd\u6620\u5c04\u7684\u673a\u5236\u7684\u6548\u7387\u4e25\u91cd\u53d7\u9650\u4e8e\u7f13\u5b58\u4f53\u7cfb\u7ed3\u6784\u3001MMU \u5730\u5740\u8f6c\u6362\u901f\u5ea6\u548c TLB \u547d\u4e2d\u7387\u3002\u5982\u679c\u80fd\u591f\u907f\u514d\u5904\u7406 I\/O \u8bf7\u6c42\u7684\u865a\u62df\u5730\u5740\u8f6c\u6362\u548c TLB \u5237\u65b0\u6240\u5e26\u6765\u7684\u5f00\u9500\uff0c\u5219\u6709\u53ef\u80fd\u6781\u5927\u5730\u63d0\u5347 I\/O \u6027\u80fd\u3002\u800c\u7f13\u51b2\u533a\u5171\u4eab\u5c31\u662f\u7528\u6765\u89e3\u51b3\u4e0a\u8ff0\u95ee\u9898\u7684\u4e00\u79cd\u6280\u672f\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u6700\u65e9\u652f\u6301 Buffer Sharing \u7684\u64cd\u4f5c\u7cfb\u7edf\u662f Solaris\u3002\u540e\u6765\uff0cLinux \u4e5f\u9010\u6b65\u652f\u6301\u4e86\u8fd9\u79cd Buffer Sharing \u7684\u6280\u672f\uff0c\u4f46\u65f6\u81f3\u4eca\u65e5\u4f9d\u7136\u4e0d\u591f\u5b8c\u6574\u548c\u6210\u719f\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u5f00\u53d1\u8005\u4eec\u5b9e\u73b0\u4e86\u4e00\u79cd\u53eb fbufs \u7684\u7f13\u51b2\u533a\u5171\u4eab\u7684\u6846\u67b6\uff0c\u4e5f\u5373<strong>\u5feb\u901f\u7f13\u51b2\u533a\uff08 Fast Buffers \uff09<\/strong>\uff0c\u4f7f\u7528\u4e00\u4e2a fbuf \u7f13\u51b2\u533a\u4f5c\u4e3a\u6570\u636e\u4f20\u8f93\u7684\u6700\u5c0f\u5355\u4f4d\uff0c\u4f7f\u7528\u8fd9\u79cd\u6280\u672f\u9700\u8981\u8c03\u7528\u65b0\u7684\u64cd\u4f5c\u7cfb\u7edf API\uff0c\u7528\u6237\u533a\u548c\u5185\u6838\u533a\u3001\u5185\u6838\u533a\u4e4b\u95f4\u7684\u6570\u636e\u90fd\u5fc5\u987b\u4e25\u683c\u5730\u5728 fbufs \u8fd9\u4e2a\u4f53\u7cfb\u4e0b\u8fdb\u884c\u901a\u4fe1\u3002fbufs \u4e3a\u6bcf\u4e00\u4e2a\u7528\u6237\u8fdb\u7a0b\u5206\u914d\u4e00\u4e2a buffer pool\uff0c\u91cc\u9762\u4f1a\u50a8\u5b58\u9884\u5206\u914d (\u4e5f\u53ef\u4ee5\u4f7f\u7528\u7684\u65f6\u5019\u518d\u5206\u914d) \u597d\u7684 buffers\uff0c\u8fd9\u4e9b buffers \u4f1a\u88ab\u540c\u65f6\u6620\u5c04\u5230\u7528\u6237\u5185\u5b58\u7a7a\u95f4\u548c\u5185\u6838\u5185\u5b58\u7a7a\u95f4\u3002fbufs \u53ea\u9700\u901a\u8fc7\u4e00\u6b21\u865a\u62df\u5185\u5b58\u6620\u5c04\u64cd\u4f5c\u5373\u53ef\u521b\u5efa\u7f13\u51b2\u533a\uff0c\u6709\u6548\u5730\u6d88\u9664\u90a3\u4e9b\u7531\u5b58\u50a8\u4e00\u81f4\u6027\u7ef4\u62a4\u6240\u5f15\u53d1\u7684\u5927\u591a\u6570\u6027\u80fd\u635f\u8017\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4f20\u7edf\u7684 Linux I\/O \u63a5\u53e3\u662f\u901a\u8fc7\u628a\u6570\u636e\u5728\u7528\u6237\u7f13\u51b2\u533a\u548c\u5185\u6838\u7f13\u51b2\u533a\u4e4b\u95f4\u8fdb\u884c\u62f7\u8d1d\u4f20\u8f93\u6765\u5b8c\u6210\u7684\uff0c\u8fd9\u79cd\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u9700\u8981\u8fdb\u884c\u5927\u91cf\u7684\u6570\u636e\u62f7\u8d1d\uff0c\u540c\u65f6\u7531\u4e8e\u865a\u62df\u5185\u5b58\u6280\u672f\u7684\u5b58\u5728\uff0cI\/O \u8fc7\u7a0b\u4e2d\u8fd8\u9700\u8981\u9891\u7e41\u5730\u901a\u8fc7 MMU \u8fdb\u884c\u865a\u62df\u5185\u5b58\u5730\u5740\u5230\u7269\u7406\u5185\u5b58\u5730\u5740\u7684\u8f6c\u6362\uff0c\u9ad8\u901f\u7f13\u5b58\u7684\u6c70\u6362\u4ee5\u53ca TLB \u7684\u5237\u65b0\uff0c\u8fd9\u4e9b\u64cd\u4f5c\u5747\u4f1a\u5bfc\u81f4\u6027\u80fd\u7684\u635f\u8017\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u800c\u5982\u679c\u5229\u7528 fbufs \u6846\u67b6\u6765\u5b9e\u73b0\u6570\u636e\u4f20\u8f93\u7684\u8bdd\uff0c\u9996\u5148\u53ef\u4ee5\u628a buffers \u90fd\u7f13\u5b58\u5230 pool \u91cc\u5faa\u73af\u5229\u7528\uff0c\u800c\u4e0d\u9700\u8981\u6bcf\u6b21\u90fd\u53bb\u91cd\u65b0\u5206\u914d\uff0c\u800c\u4e14\u7f13\u5b58\u4e0b\u6765\u7684\u4e0d\u6b62\u6709 buffers \u672c\u8eab\uff0c\u800c\u4e14\u8fd8\u4f1a\u628a\u865a\u62df\u5185\u5b58\u5730\u5740\u5230\u7269\u7406\u5185\u5b58\u5730\u5740\u7684\u6620\u5c04\u5173\u7cfb\u4e5f\u7f13\u5b58\u4e0b\u6765\uff0c\u4e5f\u5c31\u53ef\u4ee5\u907f\u514d\u6bcf\u6b21\u90fd\u8fdb\u884c\u5730\u5740\u8f6c\u6362\uff0c\u4ece\u53d1\u9001\u63a5\u6536\u6570\u636e\u7684\u5c42\u9762\u6765\u8bf4\uff0c\u7528\u6237\u8fdb\u7a0b\u548c I\/O \u5b50\u7cfb\u7edf\u6bd4\u5982\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u3001\u7f51\u5361\u7b49\u53ef\u4ee5\u76f4\u63a5\u4f20\u8f93\u6574\u4e2a\u7f13\u51b2\u533a\u672c\u8eab\u800c\u4e0d\u662f\u5176\u4e2d\u7684\u6570\u636e\u5185\u5bb9\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u4e5f\u53ef\u4ee5\u7406\u89e3\u6210\u662f\u4f20\u8f93\u5185\u5b58\u5730\u5740\u6307\u9488\uff0c\u8fd9\u6837\u5c31\u5c31\u907f\u514d\u4e86\u5927\u91cf\u7684\u6570\u636e\u5185\u5bb9\u62f7\u8d1d\uff1a\u7528\u6237\u8fdb\u7a0b\/ IO \u5b50\u7cfb\u7edf\u901a\u8fc7\u53d1\u9001\u4e00\u4e2a\u4e2a\u7684 fbuf \u5199\u51fa\u6570\u636e\u5230\u5185\u6838\u800c\u975e\u76f4\u63a5\u4f20\u9012\u6570\u636e\u5185\u5bb9\uff0c\u76f8\u5bf9\u5e94\u7684\uff0c\u7528\u6237\u8fdb\u7a0b\/ IO \u5b50\u7cfb\u7edf\u901a\u8fc7\u63a5\u6536\u4e00\u4e2a\u4e2a\u7684 fbuf \u800c\u4ece\u5185\u6838\u8bfb\u5165\u6570\u636e\uff0c\u8fd9\u6837\u5c31\u80fd\u51cf\u5c11\u4f20\u7edf\u7684\u00a0<code>read()\/write()<\/code>\u00a0\u7cfb\u7edf\u8c03\u7528\u5e26\u6765\u7684\u6570\u636e\u62f7\u8d1d\u5f00\u9500\uff1a<\/p>\n<figure data-tool=\"mdnice\u7f16\u8f91\u5668\"><img decoding=\"async\" class=\"\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoPegicaZTEE0gSTQF7ehlD8yQ6OQc4Y8ZFCQRlh13YC8qdNuzCMpHcUA\/640?wx_fmt=png&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"0.5333333333333333\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_png\/j3gficicyOvauMq3XZyq1ChVLuibDRbWLOoPegicaZTEE0gSTQF7ehlD8yQ6OQc4Y8ZFCQRlh13YC8qdNuzCMpHcUA\/640?wx_fmt=png\" data-type=\"png\" data-w=\"1200\" data-fail=\"0\" \/><\/figure>\n<ol class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section>\u53d1\u9001\u65b9\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>uf_allocate<\/code>\u00a0\u4ece\u81ea\u5df1\u7684 buffer pool \u83b7\u53d6\u4e00\u4e2a fbuf \u7f13\u51b2\u533a\uff0c\u5f80\u5176\u4e2d\u586b\u5145\u5185\u5bb9\u4e4b\u540e\u8c03\u7528\u00a0<code>uf_write<\/code>\u00a0\u5411\u5185\u6838\u533a\u53d1\u9001\u6307\u5411 fbuf \u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff1b<\/section>\n<\/li>\n<li>\n<section>I\/O \u5b50\u7cfb\u7edf\u63a5\u6536\u5230 fbuf \u4e4b\u540e\uff0c\u8c03\u7528\u00a0<code>uf_allocb<\/code>\u00a0\u4ece\u63a5\u6536\u65b9\u7528\u6237\u8fdb\u7a0b\u7684 buffer pool \u83b7\u53d6\u4e00\u4e2a fubf \u5e76\u7528\u63a5\u6536\u5230\u7684\u6570\u636e\u8fdb\u884c\u586b\u5145\uff0c\u7136\u540e\u5411\u7528\u6237\u533a\u53d1\u9001\u6307\u5411 fbuf \u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff1b<\/section>\n<\/li>\n<li>\n<section>\u63a5\u6536\u65b9\u7528\u6237\u8fdb\u7a0b\u8c03\u7528\u00a0<code>uf_get<\/code>\u00a0\u63a5\u6536\u5230 fbuf\uff0c\u8bfb\u53d6\u6570\u636e\u8fdb\u884c\u5904\u7406\uff0c\u5b8c\u6210\u4e4b\u540e\u8c03\u7528\u00a0<code>uf_deallocate<\/code>\u00a0\u628a fbuf \u653e\u56de\u81ea\u5df1\u7684 buffer pool\u3002<\/section>\n<\/li>\n<\/ol>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><strong>fbufs \u7684\u7f3a\u9677<\/strong><\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u5171\u4eab\u7f13\u51b2\u533a\u6280\u672f\u7684\u5b9e\u73b0\u9700\u8981\u4f9d\u8d56\u4e8e\u7528\u6237\u8fdb\u7a0b\u3001\u64cd\u4f5c\u7cfb\u7edf\u5185\u6838\u3001\u4ee5\u53ca I\/O \u5b50\u7cfb\u7edf (\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\uff0c\u6587\u4ef6\u7cfb\u7edf\u7b49)\u4e4b\u95f4\u534f\u540c\u5de5\u4f5c\u3002\u6bd4\u5982\uff0c\u8bbe\u8ba1\u5f97\u4e0d\u597d\u7684\u7528\u6237\u8fdb\u7a0b\u5bb9\u6613\u5c31\u4f1a\u4fee\u6539\u5df2\u7ecf\u53d1\u9001\u51fa\u53bb\u7684 fbuf \u4ece\u800c\u6c61\u67d3\u6570\u636e\uff0c\u66f4\u8981\u547d\u7684\u662f\u8fd9\u79cd\u95ee\u9898\u5f88\u96be debug\u3002\u867d\u7136\u8fd9\u4e2a\u6280\u672f\u7684\u8bbe\u8ba1\u65b9\u6848\u975e\u5e38\u7cbe\u5f69\uff0c\u4f46\u662f\u5b83\u7684\u95e8\u69db\u548c\u9650\u5236\u5374\u4e0d\u6bd4\u524d\u9762\u4ecb\u7ecd\u7684\u5176\u4ed6\u6280\u672f\u5c11\uff1a\u9996\u5148\u4f1a\u5bf9\u64cd\u4f5c\u7cfb\u7edf API \u9020\u6210\u53d8\u52a8\uff0c\u9700\u8981\u4f7f\u7528\u65b0\u7684\u4e00\u4e9b API \u8c03\u7528\uff0c\u5176\u6b21\u8fd8\u9700\u8981\u8bbe\u5907\u9a71\u52a8\u7a0b\u5e8f\u914d\u5408\u6539\u52a8\uff0c\u8fd8\u6709\u7531\u4e8e\u662f\u5185\u5b58\u5171\u4eab\uff0c\u5185\u6838\u9700\u8981\u5f88\u5c0f\u5fc3\u8c28\u614e\u5730\u5b9e\u73b0\u5bf9\u8fd9\u90e8\u5206\u5171\u4eab\u7684\u5185\u5b58\u8fdb\u884c\u6570\u636e\u4fdd\u62a4\u548c\u540c\u6b65\u7684\u673a\u5236\uff0c\u800c\u8fd9\u79cd\u5e76\u53d1\u7684\u540c\u6b65\u673a\u5236\u662f\u975e\u5e38\u5bb9\u6613\u51fa bug \u7684\u4ece\u800c\u53c8\u589e\u52a0\u4e86\u5185\u6838\u7684\u4ee3\u7801\u590d\u6742\u5ea6\uff0c\u7b49\u7b49\u3002\u56e0\u6b64\u8fd9\u4e00\u7c7b\u7684\u6280\u672f\u8fd8\u8fdc\u8fdc\u6ca1\u6709\u5230\u53d1\u5c55\u6210\u719f\u548c\u5e7f\u6cdb\u5e94\u7528\u7684\u9636\u6bb5\uff0c\u76ee\u524d\u5927\u591a\u6570\u7684\u5b9e\u73b0\u90fd\u8fd8\u5904\u4e8e\u5b9e\u9a8c\u9636\u6bb5\u3002<\/p>\n<h3 data-tool=\"mdnice\u7f16\u8f91\u5668\">\u603b\u7ed3<\/h3>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u672c\u6587\u4e2d\u6211\u4e3b\u8981\u8bb2\u89e3\u4e86 Linux I\/O \u5e95\u5c42\u539f\u7406\uff0c\u7136\u540e\u4ecb\u7ecd\u5e76\u89e3\u6790\u4e86 Linux \u4e2d\u7684 Zero-copy \u6280\u672f\uff0c\u5e76\u7ed9\u51fa\u4e86 Linux \u5bf9 I\/O \u6a21\u5757\u7684\u4f18\u5316\u548c\u6539\u8fdb\u601d\u8def\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">Linux \u7684 Zero-copy \u6280\u672f\u53ef\u4ee5\u5f52\u7eb3\u6210\u4ee5\u4e0b\u4e09\u5927\u7c7b\uff1a<\/p>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section><strong>\u51cf\u5c11\u751a\u81f3\u907f\u514d\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684\u6570\u636e\u62f7\u8d1d<\/strong>\uff1a\u5728\u4e00\u4e9b\u573a\u666f\u4e0b\uff0c\u7528\u6237\u8fdb\u7a0b\u5728\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u5e76\u4e0d\u9700\u8981\u5bf9\u6570\u636e\u8fdb\u884c\u8bbf\u95ee\u548c\u5904\u7406\uff0c\u90a3\u4e48\u6570\u636e\u5728 Linux \u7684\u00a0<code>Page Cache<\/code>\u00a0\u548c\u7528\u6237\u8fdb\u7a0b\u7684\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u4f20\u8f93\u5c31\u5b8c\u5168\u53ef\u4ee5\u907f\u514d\uff0c\u8ba9\u6570\u636e\u62f7\u8d1d\u5b8c\u5168\u5728\u5185\u6838\u91cc\u8fdb\u884c\uff0c\u751a\u81f3\u53ef\u4ee5\u901a\u8fc7\u66f4\u5de7\u5999\u7684\u65b9\u5f0f\u907f\u514d\u5728\u5185\u6838\u91cc\u7684\u6570\u636e\u62f7\u8d1d\u3002\u8fd9\u4e00\u7c7b\u5b9e\u73b0\u4e00\u822c\u662f\u662f\u901a\u8fc7\u589e\u52a0\u65b0\u7684\u7cfb\u7edf\u8c03\u7528\u6765\u5b8c\u6210\u7684\uff0c\u6bd4\u5982 Linux \u4e2d\u7684 mmap()\uff0csendfile() \u4ee5\u53ca splice() \u7b49\u3002<\/section>\n<\/li>\n<li>\n<section><strong>\u7ed5\u8fc7\u5185\u6838\u7684\u76f4\u63a5 I\/O<\/strong>\uff1a\u5141\u8bb8\u5728\u7528\u6237\u6001\u8fdb\u7a0b\u7ed5\u8fc7\u5185\u6838\u76f4\u63a5\u548c\u786c\u4ef6\u8fdb\u884c\u6570\u636e\u4f20\u8f93\uff0c\u5185\u6838\u5728\u4f20\u8f93\u8fc7\u7a0b\u4e2d\u53ea\u8d1f\u8d23\u4e00\u4e9b\u7ba1\u7406\u548c\u8f85\u52a9\u7684\u5de5\u4f5c\u3002\u8fd9\u79cd\u65b9\u5f0f\u5176\u5b9e\u548c\u7b2c\u4e00\u79cd\u6709\u70b9\u7c7b\u4f3c\uff0c\u4e5f\u662f\u8bd5\u56fe\u907f\u514d\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u4e4b\u95f4\u7684\u6570\u636e\u4f20\u8f93\uff0c\u53ea\u662f\u7b2c\u4e00\u79cd\u65b9\u5f0f\u662f\u628a\u6570\u636e\u4f20\u8f93\u8fc7\u7a0b\u653e\u5728\u5185\u6838\u6001\u5b8c\u6210\uff0c\u800c\u8fd9\u79cd\u65b9\u5f0f\u5219\u662f\u76f4\u63a5\u7ed5\u8fc7\u5185\u6838\u548c\u786c\u4ef6\u901a\u4fe1\uff0c\u6548\u679c\u7c7b\u4f3c\u4f46\u539f\u7406\u5b8c\u5168\u4e0d\u540c\u3002<\/section>\n<\/li>\n<li>\n<section><strong>\u5185\u6838\u7f13\u51b2\u533a\u548c\u7528\u6237\u7f13\u51b2\u533a\u4e4b\u95f4\u7684\u4f20\u8f93\u4f18\u5316<\/strong>\uff1a\u8fd9\u79cd\u65b9\u5f0f\u4fa7\u91cd\u4e8e\u5728\u7528\u6237\u8fdb\u7a0b\u7684\u7f13\u51b2\u533a\u548c\u64cd\u4f5c\u7cfb\u7edf\u7684\u9875\u7f13\u5b58\u4e4b\u95f4\u7684 CPU \u62f7\u8d1d\u7684\u4f18\u5316\u3002\u8fd9\u79cd\u65b9\u6cd5\u5ef6\u7eed\u4e86\u4ee5\u5f80\u90a3\u79cd\u4f20\u7edf\u7684\u901a\u4fe1\u65b9\u5f0f\uff0c\u4f46\u66f4\u7075\u6d3b\u3002<\/section>\n<\/li>\n<\/ul>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\">\u672c\u6587\u4ece\u865a\u62df\u5185\u5b58\u3001I\/O \u7f13\u51b2\u533a\uff0c\u7528\u6237\u6001&amp;\u5185\u6838\u6001\u4ee5\u53ca I\/O \u6a21\u5f0f\u7b49\u7b49\u77e5\u8bc6\u70b9\u5168\u9762\u800c\u53c8\u8be6\u5c3d\u5730\u5256\u6790\u4e86 Linux \u7cfb\u7edf\u7684 I\/O \u5e95\u5c42\u539f\u7406\uff0c\u5206\u6790\u4e86 Linux \u4f20\u7edf\u7684 I\/O \u6a21\u5f0f\u7684\u5f0a\u7aef\uff0c\u8fdb\u800c\u5f15\u5165 Linux Zero-copy \u96f6\u62f7\u8d1d\u6280\u672f\u7684\u4ecb\u7ecd\u548c\u539f\u7406\u89e3\u6790\uff0c\u901a\u8fc7\u5c06\u96f6\u62f7\u8d1d\u6280\u672f\u548c\u4f20\u7edf\u7684 I\/O \u6a21\u5f0f\u8fdb\u884c\u533a\u5206\u548c\u5bf9\u6bd4\uff0c\u5e26\u9886\u8bfb\u8005\u7ecf\u5386\u4e86 Linux I\/O \u7684\u6f14\u5316\u5386\u53f2\uff0c\u901a\u8fc7\u5e2e\u52a9\u8bfb\u8005\u7406\u89e3 Linux \u5185\u6838\u5bf9 I\/O \u6a21\u5757\u7684\u4f18\u5316\u6539\u8fdb\u601d\u8def\uff0c\u76f8\u4fe1\u4e0d\u4ec5\u4ec5\u662f\u8ba9\u8bfb\u8005\u4e86\u89e3 Linux \u5e95\u5c42\u7cfb\u7edf\u7684\u8bbe\u8ba1\u539f\u7406\uff0c\u66f4\u80fd\u5bf9\u8bfb\u8005\u4eec\u5728\u4ee5\u540e\u4f18\u5316\u6539\u8fdb\u81ea\u5df1\u7684\u7a0b\u5e8f\u8bbe\u8ba1\u8fc7\u7a0b\u4e2d\u80fd\u591f\u6709\u6240\u542f\u53d1\u3002<\/p>\n<p data-tool=\"mdnice\u7f16\u8f91\u5668\"><strong>\u53c2\u8003&amp;\u5ef6\u4f38\u9605\u8bfb<\/strong><\/p>\n<ul class=\"list-paddingleft-2\" data-tool=\"mdnice\u7f16\u8f91\u5668\">\n<li>\n<section><a href=\"http:\/\/index-of.es\/Varios-2\/Modern%20Operating%20Systems%204th%20Edition.pdf\" data-linktype=\"2\">MODERN OPERATING SYSTEMS<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/www.linuxjournal.com\/article\/6345\" data-linktype=\"2\">Zero Copy I: User-Mode Perspective<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"http:\/\/www.cs.inf.ethz.ch\/group\/stricker\/sada\/archive\/chihaia.pdf\" data-linktype=\"2\">Message Passing for Gigabit\/s Networks with \u201cZero-Copy\u201d under Linux<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/static.aminer.org\/pdf\/PDF\/000\/253\/158\/design_and_implementation_of_zero_copy_data_path_for_efficient.pdf\" data-linktype=\"2\">ZeroCopy: Techniques, Benefits and Pitfalls<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/lwn.net\/Articles\/726917\/\" data-linktype=\"2\">Zero-copy networking<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/lwn.net\/Articles\/28548\/\" data-linktype=\"2\">Driver porting: Zero-copy user-space access<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/netdevconf.info\/2.1\/papers\/netdev.pdf\" data-linktype=\"2\">sendmsg copy avoidance with MSG_ZEROCOPY<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/medium.com\/@xunnan.xu\/its-all-about-buffers-zero-copy-mmap-and-java-nio-50f2a1bfc05c\" data-linktype=\"2\">It\u2019s all about buffers: zero-copy, mmap and Java NIO<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/www.joshbialkowski.com\/posts\/2018\/linux_zero_copy\/linux-zero-copy.html\" data-linktype=\"2\">Linux Zero Copy<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/lwn.net\/Articles\/178199\/\" data-linktype=\"2\">Two new system calls: splice() and sync_file_range()<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/lwn.net\/Articles\/118750\/\" data-linktype=\"2\">Circular pipes<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/lwn.net\/Articles\/712467\/\" data-linktype=\"2\">The future of the page cache<\/a><\/section>\n<\/li>\n<li>\n<section><a href=\"https:\/\/lwn.net\/Articles\/386778\/\" data-linktype=\"2\">Provide a zero-copy method on KVM virtio-net<\/a><\/section>\n<\/li>\n<\/ul>\n<section><\/section>\n<section><\/section>\n<p><img decoding=\"async\" class=\"rich_pages \" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_jpg\/j3gficicyOvavksEUqEQR32xesLGgyRHkvAgibobvkqLV8hJYttibWlnuPr8GDPUlLU1LUaxmshEiarlcyQHpSWW0Mw\/640?wx_fmt=jpeg&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"2.9953703703703702\" data-s=\"300,640\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_jpg\/j3gficicyOvavksEUqEQR32xesLGgyRHkvAgibobvkqLV8hJYttibWlnuPr8GDPUlLU1LUaxmshEiarlcyQHpSWW0Mw\/640?wx_fmt=jpeg\" data-type=\"jpeg\" data-w=\"1080\" data-fail=\"0\" \/><img decoding=\"async\" class=\"rich_pages \" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_jpg\/j3gficicyOvavksEUqEQR32xesLGgyRHkvYXQ3coZgLoKQdiaiarPFhIeCUyVc0sF2Urfw4nne0MQpvUjZgsKekS4A\/640?wx_fmt=jpeg&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1&amp;wx_co=1\" alt=\"\u56fe\u7247\" crossorigin=\"anonymous\" data-ratio=\"3.0833333333333335\" data-s=\"300,640\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_jpg\/j3gficicyOvavksEUqEQR32xesLGgyRHkvYXQ3coZgLoKQdiaiarPFhIeCUyVc0sF2Urfw4nne0MQpvUjZgsKekS4A\/640?wx_fmt=jpeg\" data-type=\"jpeg\" data-w=\"1080\" data-fail=\"0\" \/><\/p>\n<section><\/section>\n<p><img decoding=\"async\" class=\"rich_pages  __bg_gif\" src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_gif\/j3gficicyOvatricjRxhpM1x45aB6doaVg7WMhINPwOiaqpskia1kH7hgibO0dicW2HLcW8HRGMzESQwehIcyckLXtwsA\/640?wx_fmt=gif&amp;tp=webp&amp;wxfrom=5&amp;wx_lazy=1\" alt=\"\u56fe\u7247\" data-ratio=\"0.729264475743349\" data-src=\"https:\/\/mmbiz.qpic.cn\/mmbiz_gif\/j3gficicyOvatricjRxhpM1x45aB6doaVg7WMhINPwOiaqpskia1kH7hgibO0dicW2HLcW8HRGMzESQwehIcyckLXtwsA\/640?wx_fmt=gif\" data-type=\"gif\" data-w=\"639\" data-order=\"1\" data-fail=\"0\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u539f\u6587\u5730\u5740 \u4f5c\u8005\uff1aallanpan\uff0c\u817e\u8baf <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[24],"tags":[121],"class_list":["post-4911","post","type-post","status-publish","format-standard","hentry","category-value_docs","tag-05-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/4911","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/comments?post=4911"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/4911\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=4911"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=4911"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=4911"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}