{"id":1209,"date":"2018-05-03T23:37:24","date_gmt":"2018-05-03T15:37:24","guid":{"rendered":"https:\/\/damogame.cn:15443\/wordpress\/?p=1209"},"modified":"2018-05-03T23:37:24","modified_gmt":"2018-05-03T15:37:24","slug":"%e9%80%8f%e5%bd%bb-linux-unix-%e4%ba%94%e7%a7%8d-io-%e6%a8%a1%e5%9e%8b","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/1209","title":{"rendered":"\u900f\u5f7b Linux (Unix) \u4e94\u79cd IO \u6a21\u578b"},"content":{"rendered":"<div class=\"article-title-box\">\n<h6 class=\"title-article\">\u900f\u5f7b Linux (Unix) \u4e94\u79cd IO \u6a21\u578b<\/h6>\n<\/div>\n<div class=\"article-info-box\">\n<div class=\"article-bar-top d-flex\"><span class=\"time\">2017\u5e7401\u670817\u65e5 13:51:58<\/span><\/p>\n<div class=\"float-right\"><span class=\"read-count\">\u9605\u8bfb\u6570\uff1a1173<\/span><\/div>\n<\/div>\n<\/div>\n<article>\n<div id=\"article_content\" class=\"article_content csdn-tracking-statistics\" data-pid=\"blog\" data-mod=\"popu_307\" data-dsm=\"post\">\n<div class=\"htmledit_views\">\n<h3><a name=\"t0\"><\/a>IO\u6a21\u578b<\/h3>\n<p>&nbsp;<\/p>\n<p>\u7528\u4e00\u5e45\u56fe\u8868\u793a\u6240\u652f\u6301\u7684I\/O\u6a21\u578b<\/p>\n<p><img decoding=\"async\" class=\"alignCenter\" src=\"http:\/\/www.chinastor.org\/upload\/2017-01\/170117130728745.png\" alt=\"\" \/><\/p>\n<p>\u7eb5\u5411\u7ef4\u5ea6\u662f\u201c\u963b\u585e\uff08Blocking\uff09\u201d\u3001\u201c\u975e\u963b\u585e\uff08Non-blocking\uff09\u201d\uff1b\u6a2a\u5411\u7ef4\u5ea6\u662f\u201c\u540c\u6b65\u201d\u3001\u201c\u5f02\u6b65\u201d\u3002\u603b\u7ed3\u8d77\u6765\u662f\u56db\u79cd\u6a21\u578b\u00a0\u540c\u6b65\u963b\u585e\u3001\u540c\u6b65\u975e\u963b\u585e\uff1b\u5f02\u6b65\u963b\u585e\u3001\u5f02\u6b65\u975e\u963b\u585e\u00a0\u3002\u300aUnix\u7f51\u7edc\u7f16\u7a0b\u300b\u4e2d\u5212\u5206\u51fa\u4e86\u201c\u7b2c\u4e94\u79cd\u201d\u6a21\u578b\u2014\u2014\u201c\u4fe1\u53f7\u9a71\u52a8\u5f0fIO\u201d\u5176\u5b9e\u5c5e\u4e8e\u5f02\u6b65\u963b\u585e\u7c7b\u578b\uff0c\u8fd9\u79cd\u6a21\u578b\u7684\u901a\u77e5\u65b9\u5f0f\u6709\u591a\u79cd\u591a\u6837\u540e\u9762\u5c55\u5f00\u8bf4\u660e\u3002<\/p>\n<h3><a name=\"t1\"><\/a>\u540c\u6b65\/\u5f02\u6b65\u3001\u963b\u585e\/\u975e\u963b\u585e<\/h3>\n<p>&nbsp;<\/p>\n<p>\u4ece\u5185\u6838\u89d2\u5ea6\u770bI\/O\u64cd\u4f5c\u5206\u4e3a\u4e24\u6b65\uff1a\u7528\u6237\u5c42API\u8c03\u7528\uff1b\u5185\u6838\u5c42\u5b8c\u6210\u7cfb\u7edf\u8c03\u7528\uff08\u53d1\u8d77I\/O\u8bf7\u6c42\uff09\u3002\u6240\u4ee5\u201c\u5f02\u6b65\/\u540c\u6b65\u201d\u7684\u662f\u6307API\u8c03\u7528\uff1b\u201c\u963b\u585e\/\u975e\u963b\u585e\u201d\u662f\u6307\u5185\u6838\u5b8c\u6210I\/O\u8c03\u7528\u7684\u6a21\u5f0f\u3002\u7528\u4e00\u5e45\u56fe\u8868\u793a\u66f4\u52a0\u660e\u663e<\/p>\n<p><img decoding=\"async\" class=\"alignCenter\" src=\"http:\/\/www.chinastor.org\/upload\/2017-01\/170117130728744.jpg\" alt=\"\" \/><\/p>\n<p>\u540c\u6b65\u662f\u6307\u51fd\u6570\u5b8c\u6210\u4e4b\u524d\u4f1a\u4e00\u76f4\u7b49\u5f85\uff1b\u00a0\u963b\u585e\u00a0\u662f\u6307\u7cfb\u7edf\u8c03\u7528\u7684\u65f6\u5019\u8fdb\u7a0b\u4f1a\u88ab\u8bbe\u7f6e\u4e3aSleep\u72b6\u6001\u76f4\u5230\u7b49\u5f85\u7684\u4e8b\u4ef6\u53d1\u751f\uff08\u6bd4\u5982\u6709\u65b0\u7684\u6570\u636e\uff09\u3002\u660e\u767d\u8fd9\u4e00\u70b9\u4e4b\u540e\u518d\u770b\u8fd9\u4e94\u79cd\u6a21\u578b\u76f8\u4fe1\u5c31\u4f1a\u6e05\u6670\u5f88\u591a\uff0c\u6211\u4eec\u6328\u4e2a\u5206\u6790\uff1a<\/p>\n<h4>\u540c\u6b65\u963b\u585e<\/h4>\n<p>&nbsp;<\/p>\n<p>\u8fd9\u79cd\u6a21\u578b\u6700\u4e3a\u5e38\u89c1\uff0c\u7528\u6237\u7a7a\u95f4\u8c03\u7528API\uff08\u00a0<code>read<\/code>\u00a0\u3001\u00a0<code>write<\/code>\u00a0)\u4f1a\u8f6c\u5316\u6210\u4e00\u4e2aI\/O\u8bf7\u6c42\uff0c\u4e00\u76f4\u7b49\u5230I\/O\u8bf7\u6c42\u5b8c\u6210API\u8c03\u7528\u624d\u4f1a\u5b8c\u6210\u3002\u8fd9\u610f\u5473\u7740\uff1a\u00a0\u5728API\u8c03\u7528\u671f\u95f4\u7528\u6237\u7a0b\u5e8f\u662f\u540c\u6b65\u7684\u7684\uff1b\u8fd9\u4e2aAPI\u8c03\u7528\u4f1a\u5bfc\u81f4\u7cfb\u7edf\u4ee5\u963b\u585e\u7684\u6a21\u5f0f\u6267\u884cI\/O\uff0c\u5982\u679c\u6b64\u65f6\u6ca1\u6709\u6570\u636e\u5219\u4e00\u76f4\u201c\u7b49\u5f85\u201d\uff08\u653e\u5f03CPU\u4e3b\u52a8\u6302\u8d77\u2014\u2014Sleep\u72b6\u6001\uff09\u00a0\uff08\u6ce8\u610f\uff0c\u5bf9\u4e8e\u786c\u76d8\u6765\u8bf4\u662f\u4e0d\u4f1a\u51fa\u73b0\u963b\u585e\u7684\uff0c\u65e0\u8bba\u662f\u4ec0\u4e48\u65f6\u5019\u8bfb\u5b83\u603b\u662f\u6709\u6570\u636e\u3002\u5e38\u89c1\u7684\u963b\u585e\u8bbe\u5907\u662f\u7ec8\u7aef\u3001\u7f51\u5361\u4e4b\u7c7b\u7684\uff09\u3002<\/p>\n<p><img decoding=\"async\" class=\"alignCenter\" src=\"http:\/\/www.chinastor.org\/upload\/2017-01\/170117130728742.jpg\" alt=\"\" \/><\/p>\n<p>\u4ee5\u00a0<code>read<\/code>\u00a0\u4e3a\u4f8b\u5b50\uff0c\u5b83\u7531\u4e09\u4e2a\u53c2\u6570\u7ec4\u6210\uff0c\u7b2c\u4e00\u4e2a\u51fd\u6570\u662f\u6587\u4ef6\u63cf\u8ff0\u7b26\uff1b\u7b2c\u4e8c\u4e2a\u662f\u00a0\u5e94\u7528\u7f13\u51b2\u00a0\uff1b\u7b2c\u4e09\u4e2a\u53c2\u6570\u662f\u9700\u8981\u8bfb\u53d6\u7684\u5b57\u8282\u6570\u3002\u7ecf\u8fc7\u7cfb\u7edf\u8c03\u7528\u4f1a\u4ee5\u963b\u585e\u6a21\u5f0f\u6267\u884cI\/O\uff0cI\/O\u6a21\u5757\u8bfb\u53d6\u6570\u636e\u540e\u4f1a\u653e\u5165\u5230PageCache\u4e2d\uff1b\u6700\u540e\u4e00\u6b65\u662f\u628a\u6570\u636e\u4ecePageCache\u590d\u5236\u5230\u00a0\u5e94\u7528\u7f13\u51b2\u00a0\u3002\u5982\u679cI\/O\u8bf7\u6c42\u65e0\u6cd5\u5f97\u5230\u6ee1\u8db3\u2014\u2014\u6ca1\u6709\u6570\u636e\uff0c\u5219\u4e3b\u52a8\u8ba9\u51faCPU\u76f4\u5230\u00a0\u6709\u6570\u636e\u00a0\uff08\u6ce8\u610f\uff0c\u5373\u4fbf\u7cfb\u7edf\u8c03\u7528\u8ba9\u51faCPU\u4e5f\u672a\u5fc5\u771f\u7684\u5c31\u8ba9\u51fa\u3002read\u51fd\u6570\u662f\u540c\u6b65\u7684\uff0c\u6240\u4ee5CPU\u8fd8\u662f\u4f1a\u88ab\u7528\u6237\u7a7a\u95f4\u4ee3\u7801\u5360\u7528\uff09\u3002<\/p>\n<h4>\u540c\u6b65\u975e\u963b\u585e<\/h4>\n<p>&nbsp;<\/p>\n<p>\u8fd9\u79cd\u6a21\u5f0f\u901a\u8fc7\u8c03\u7528\u00a0<code>read<\/code>\u00a0\u3001\u00a0<code>write<\/code>\u00a0\u7684\u65f6\u5019\u6307\u5b9a\u00a0<code>O_NONBLOCK<\/code>\u00a0\u53c2\u6570\u3002\u548c\u201c\u540c\u6b65\u963b\u585e\u201d\u6a21\u5f0f\u7684\u533a\u522b\u5728\u4e8e\u7cfb\u7edf\u8c03\u7528\u7684\u65f6\u5019\u5b83\u662f\u4ee5\u975e\u963b\u585e\u7684\u65b9\u5f0f\u6267\u884c\uff0c\u65e0\u8bba\u662f\u5426\u6709\u6570\u636e\u90fd\u4f1a\u7acb\u5373\u8fd4\u56de\u3002\u00a0\u4ee5\u00a0<code>read<\/code>\u00a0\u4e3a\u4f8b\uff0c\u5982\u679c\u6210\u529f\u8bfb\u53d6\u5230\u6570\u636e\u5b83\u8fd4\u56de\u8bfb\u53d6\u5230\u7684\u5b57\u8282\u6570\uff1b\u5982\u679c\u6b64\u65f6\u6ca1\u6709\u6570\u636e\u5219\u8fd4\u56de-1\uff0c\u540c\u65f6\u8bbe\u7f6eerrno\u4e3aEAGAIN\uff08\u6216\u8005EWOULDBLOCK\uff0c\u4e8c\u8005\u76f8\u540c\uff09\u3002\u6240\u4ee5\u8fd9\u79cd\u6a21\u5f0f\u4e0b\u6211\u4eec\u4e00\u822c\u4f1a\u7528\u4e00\u4e2a\u201c\u5faa\u73af\u201d\u4e0d\u505c\u7684\u5c1d\u8bd5\u8bfb\u53d6\u6570\u636e\uff0c\u5904\u7406\u6570\u636e\u3002<\/p>\n<h4>\u5f02\u6b65\u963b\u585e<\/h4>\n<p>&nbsp;<\/p>\n<p>\u540c\u6b65\u6a21\u578b\u6700\u4e3b\u8981\u7684\u95ee\u9898\u662f\u5360\u7528CPU\uff0c\u00a0\u963b\u585eI\/O\u4f1a\u4e3b\u52a8\u8ba9\u51faCPU\u4f46\u662f\u7528\u6237\u7a7a\u95f4\u7684\u7cfb\u7edf\u8c03\u7528\u8fd8\u662f\u4e0d\u4f1a\u8fd4\u56de\u4f9d\u7136\u8017\u8d39CPU\uff1b\u975e\u963b\u585eI\/O\u5fc5\u987b\u4e0d\u505c\u7684\u201c\u8f6e\u8be2\u201d\u4e0d\u65ad\u5c1d\u8bd5\u8bfb\u53d6\u6570\u636e\uff08\u4f1a\u8017\u8d39\u66f4\u591aCPU\u66f4\u52a0\u4f4e\u6548\uff09\u3002\u5982\u679c\u4ed4\u7ec6\u5206\u6790\u540c\u6b65\u6a21\u578b\u9738\u5360CPU\u7684\u539f\u56e0\u4e0d\u96be\u5f97\u51fa\u7ed3\u8bba\u2014\u2014\u90fd\u662f\u5728\u7b49\u5f85\u6570\u636e\u5230\u6765\u3002\u5f02\u6b65\u6a21\u5f0f\u6b63\u662f\u610f\u8bc6\u5230\u8fd9\u4e00\u70b9\u6240\u4ee5\u628aI\/O\u8bfb\u53d6\u7ec6\u5316\u4e3a\u00a0\u8ba2\u9605I\/O\u4e8b\u4ef6\uff0c\u5b9e\u9645I\/O\u8bfb\u5199\uff0c\u5728\u201c\u8ba2\u9605I\/O\u4e8b\u4ef6\u201d\u4e8b\u4ef6\u90e8\u5206\u4f1a\u4e3b\u52a8\u8ba9\u51faCPU\u76f4\u5230\u4e8b\u4ef6\u53d1\u751f\u00a0\u3002\u5f02\u6b65\u6a21\u5f0f\u4e0b\u7684I\/O\u51fd\u6570\u548c\u540c\u6b65\u6a21\u5f0f\u4e0b\u7684I\/O\u51fd\u6570\u662f\u4e00\u6837\u7684\uff08\u90fd\u662f\u00a0<code>read<\/code>\u00a0\u3001\u00a0<code>write<\/code>\u00a0\uff09\u552f\u4e00\u7684\u533a\u522b\u662f\u5f02\u6b65\u6a21\u5f0f\u00a0\u201c\u8bfb\u201d\u5fc5\u6709\u6570\u636e\u00a0\u800c\u540c\u6b65\u6a21\u5f0f\u5219\u672a\u5fc5\u3002\u00a0\u5e38\u89c1\u7684\u5f02\u6b65\u963b\u585e\u51fd\u6570\u5305\u62ec\u00a0<code>select<\/code>\u00a0\uff0c\u00a0<code>poll<\/code>\u00a0\uff0c\u00a0<code>epoll<\/code>\u00a0\uff0c\u8fd9\u4e9b\u51fd\u6570\u7684\u7528\u6cd5\u9700\u8981\u82b1\u8d39\u76f8\u5f53\u5927\u7684\u7bc7\u5e45\u4ecb\u7ecd\u800c\u8fd9\u7bc7\u6587\u7ae0\u6211\u60f3\u96c6\u4e2d\u7cbe\u529b\u4ecb\u7ecd\u201cI\/O\u6a21\u578b\u201d\u3002\u4ee5\u00a0<code>select<\/code>\u00a0\u4e3a\u4f8b\u6211\u4eec\u770b\u4e00\u4e0b\u5927\u81f4\u539f\u7406<\/p>\n<p><img decoding=\"async\" class=\"alignCenter\" src=\"http:\/\/www.chinastor.org\/upload\/2017-01\/170117130728743.jpg\" alt=\"\" \/><\/p>\n<p>\u5f02\u6b65\u6a21\u5f0f\u4e0b\u6211\u4eec\u7684API\u8c03\u7528\u5206\u4e3a\u4e24\u6b65\uff0c\u7b2c\u4e00\u6b65\u662f\u901a\u8fc7\u00a0<code>select<\/code>\u00a0\u8ba2\u9605\u8bfb\u5199\u4e8b\u4ef6\u00a0\u8fd9\u4e2a\u51fd\u6570\u4f1a\u4e3b\u52a8\u8ba9\u51faCPU\u76f4\u5230\u4e8b\u4ef6\u53d1\u751f\uff08\u8bbe\u7f6e\u4e3aSleep\u72b6\u6001\uff0c\u7b49\u5f85\u4e8b\u4ef6\u53d1\u751f\uff09\u00a0\uff1bselect\u4e00\u65e6\u8fd4\u56de\u5c31\u8bc1\u660e\u53ef\u4ee5\u5f00\u59cb\u8bfb\u4e86\u6240\u4ee5\u7b2c\u4e8c\u90e8\u662f\u901a\u8fc7\u00a0<code>read<\/code>\u00a0\u8bfb\u53d6\u6570\u636e(\u00a0\u201c\u8bfb\u201d\u5fc5\u6709\u6570\u636e\u00a0)\u3002<\/p>\n<h4>\u5f02\u6b65\u963b\u585e\u6a21\u578b\u4e4b\u4fe1\u53f7\u9a71\u52a8<\/h4>\n<p>&nbsp;<\/p>\n<p>\u201c\u5b8c\u7f8e\u4e3b\u4e49\u8005\u201d\u770b\u4e86\u4e0a\u9762\u7684\u00a0<code>select<\/code>\u00a0\u4e4b\u540e\u4f1a\u6709\u70b9\u4e0d\u723d\u2014\u2014\u6211\u8fd8\u8981\u201c\u7b49\u5f85\u201d\u8bfb\u5199\u4e8b\u4ef6\uff08\u5373\u4fbf\u00a0<code>select<\/code>\u00a0\u4f1a\u4e3b\u52a8\u8ba9\u51faCPU\uff09\uff0c\u80fd\u4e0d\u80fd\u6709\u8bfb\u5199\u4e8b\u4ef6\u7684\u65f6\u5019\u4e3b\u52a8\u901a\u77e5\u6211\u554a\uff1f\u3002\u501f\u52a9\u201c\u4fe1\u53f7\u201d\u673a\u5236\u6211\u4eec\u53ef\u4ee5\u5b9e\u73b0\u8fd9\u4e2a\uff0c\u4f46\u662f\u8fd9\u5e76\u4e0d\u5b8c\u7f8e\u800c\u4e14\u6709\u70b9\u5f04\u5de7\u6210\u62d9\u7684\u610f\u601d\u3002\u00a0\u5177\u4f53\u7528\u6cd5\uff1a\u901a\u8fc7\u00a0<code>fcntl<\/code>\u00a0\u51fd\u6570\u8bbe\u7f6e\u4e00\u4e2a\u00a0<code>F_GETFL|O_ASYNC<\/code>\u00a0\uff08 \u66fe\u7ecf\u4fe1\u53f7\u9a71\u52a8I\/O\u4e5f\u53eb\u201c\u5f02\u6b65I\/O\u201d\u6240\u4ee5\u624d\u6709\u00a0<code>O_ASYNC<\/code>\u00a0\u7684\u8bf4\u6cd5\uff09\uff0c\u5f53\u6709I\/O\u65f6\u95f4\u7684\u65f6\u5019\u64cd\u4f5c\u7cfb\u7edf\u4f1a\u89e6\u53d1\u00a0<code>SIGIO<\/code>\u00a0\u4fe1\u53f7\u3002\u5728\u7a0b\u5e8f\u91cc\u53ea\u9700\u8981\u7ed1\u5b9a\u00a0<code>SIGIO<\/code>\u00a0\u4fe1\u53f7\u7684\u5904\u7406\u51fd\u6570\u5c31\u53ef\u4ee5\u4e86\u3002\u4f46\u662f\u8fd9\u91cc\u6709\u4e2a\u95ee\u9898\u2014\u2014\u00a0\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u7531\u54ea\u4e2a\u8fdb\u7a0b\u6267\u884c\u5462\uff1f\u00a0\uff0c\u7b54\u6848\u662f\uff1a\u201c\u5c5e\u4e3b\u201d\u8fdb\u7a0b\u3002\u64cd\u4f5c\u7cfb\u7edf\u53ea\u8d1f\u8d23\u53c2\u6570\u4fe1\u53f7\u800c\u5b9e\u9645\u7684\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u5fc5\u987b\u7531\u7528\u6237\u7a7a\u95f4\u7684\u8fdb\u7a0b\u5b9e\u73b0\u3002\uff08\u8fd9\u5c31\u662f\u8bbe\u7f6e\u00a0<code>F_SETOWN<\/code>\u00a0\u4e3a\u5f53\u524d\u8fdb\u7a0bPID\u7684\u539f\u56e0\uff09\u00a0\u4fe1\u53f7\u9a71\u52a8\u6027\u80fd\u8981\u6bd4\u00a0<code>select<\/code>\u00a0\u3001\u00a0<code>poll<\/code>\u00a0\u9ad8\uff08\u907f\u514d\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u590d\u5236\uff09\u4f46\u662f\u7f3a\u70b9\u662f\u81f4\u547d\u7684\u2014\u2014*Linux\u4e2d\u4fe1\u53f7\u961f\u5217\u662f\u6709\u9650\u5236\u7684\u5982\u679c\u64cd\u8fc7\u8fd9\u4e2a\u6570\u5b57\u95ee\u9898\u5c31\u5b8c\u5168\u65e0\u6cd5\u8bfb\u53d6\u6570\u636e\u3002<\/p>\n<h4>\u5f02\u6b65\u975e\u963b\u585e<\/h4>\n<p>&nbsp;<\/p>\n<p>\u8fd9\u79cd\u6a21\u578b\u662f\u6700\u201c\u7701\u4e8b\u201d\u7684\u6a21\u578b\uff0c\u7cfb\u7edf\u8c03\u7528\u5b8c\u6210\u4e4b\u540e\u5c31\u53ea\u8981\u5750\u7b49\u6570\u636e\u5c31\u53ef\u4ee5\u4e86\u3002\u662f\u4e0d\u662f\u7279\u522b\u723d\uff1f\u5176\u5b9e\u4e0d\u7136\uff0c\u95ee\u9898\u51fa\u5728\u5b9e\u73b0\u4e0a\u3002Linux\u4e0a\u7684AIO\u4e24\u4e2a\u5b9e\u73b0\u7248\u672c\uff0cPOSIX\u7684\u5b9e\u73b0\u6700\u70c2\uff08\u84dd\u8272\u5de8\u4eba\u7684\u9505\uff09\u6027\u80fd\u5f88\u5dee\u800c\u4e14\u662f\u57fa\u4e8e\u201c\u4e8b\u4ef6\u9a71\u52a8\u201d\u8fd8\u4f1a\u51fa\u73b0\u201c\u4fe1\u53f7\u961f\u5217\u4e0d\u8db3\u201d\u7684\u95ee\u9898(\u6240\u4ee5\u5b83\u5c31\u5077\u5077\u7684\u521b\u5efa\u7ebf\u7a0b\uff0c\u5bfc\u81f4\u7ebf\u7a0b\u4e5f\u4e0d\u53ef\u63a7\u4e86)\uff1b\u4e00\u4e2a\u662fLinux\u81ea\u5df1\u5b9e\u73b0\u7684\uff08redhat\u8d21\u732e\uff09Native AIO\u3002Native AIO\u4e3b\u8981\u6d89\u53ca\u5230\u7684\u4e24\u4e2a\u51fd\u6570<code>io_submit<\/code>\u00a0\u8bbe\u7f6e\u9700\u8981I\/O\u52a8\u4f5c\uff08\u8bfb\u3001\u5199\uff0c\u6570\u636e\u5927\u5c0f\uff0c\u5e94\u7528\u7f13\u51b2\u533a\u7b49\uff09\uff1b\u00a0<code>io_getevents<\/code>\u00a0\u7b49\u5f85I\/O\u52a8\u4f5c\u5b8c\u6210\u3002\u6ca1\u9519\uff0c\u5373\u4fbf\u4f60\u7684\u6574\u4e2aI\/O\u884c\u4e3a\u662f\u975e\u963b\u585e\u7684\u8fd8\u662f\u9700\u8981\u6709\u4e00\u4e2a\u529e\u6cd5\u77e5\u9053\u6570\u636e\u662f\u5426\u8bfb\u53d6\/\u5199\u5165\u6210\u529f\u3002<\/p>\n<p><img decoding=\"async\" class=\"alignCenter\" src=\"http:\/\/www.chinastor.org\/upload\/2017-01\/170117130728741.jpg\" alt=\"\" \/><\/p>\n<p>\u6ce8\u610f\u56fe\u4e2d\uff0c\u5185\u6838\u4e0d\u518d\u4e3aI\/O\u5206\u914dPageCache\uff0c\u6240\u6709\u7684\u6570\u636e\u5fc5\u987b\u6709\u7528\u6237\u81ea\u5df1\u8bfb\u53d6\u5230\u5e94\u7528\u7f13\u51b2\u4e2d\u7ef4\u62a4\u3002\u6240\u4ee5AIO\u4e00\u5b9a\u662f\u548c\u201c\u76f4\u63a5I\/O\u201d\u914d\u5408\u4f7f\u7528\u3002\u00a0AIO\u9488\u5bf9\u7f51\u5361\u8bbe\u5907\u7684\u610f\u4e49\u4e0d\u5927\uff0c\u9996\u5148\u5b83\u7684\u5b9e\u73b0\u672c\u8d28\u4e0a\u548cepoll\u5dee\u4e0d\u591a\uff1b\u5176\u6b21\u5b83\u5728Linux\u4e2d\u7684\u4f5c\u7528\u66f4\u591a\u7684\u662f\u7528\u4e8e\u78c1\u76d8I\/O\uff08\u5f02\u6b65\u975e\u963b\u585e\u53ef\u4ee5\u4e0d\u7528\u591a\u7ebf\u7a0b\u5c31\u9020\u6210\u5927\u91cf\u7684I\/O\u8bf7\u6c42\u4fbf\u4e8eI\/O\u6a21\u5757\u201c\u5408\u5e76\u201d\u4f18\u5316\u4f1a\u63d0\u9ad8\u6574\u4f53I\/O\u7684\u541e\u5410\u7387\u2014\u2014\u800c\u4e14\u5bf9CPU\u5f00\u9500\u6bd4\u8f83\u5c11\uff09\u3002\u00a0\u5728Nginx\u4e2d\u7528\u4e86\u4e00\u4e2a\u6280\u5de7\uff0c\u53ef\u4ee5\u5b9e\u73b0AIO\u548cepoll\u8054\u52a8\uff0cAIO\u8bfb\u53d6\u5230\u6570\u636e\u540e\u89e6\u53d1epoll\u53d1\u9001\u6570\u636e\u3002\uff08\u8fd9\u4e2a\u7279\u6027\u662f\u975e\u5e38\u5c34\u5c2c\u7684\uff0c\u5982\u679c\u662f\u78c1\u76d8\u6587\u4ef6\u5b8c\u5168\u53ef\u4ee5\u7528sendfile\u641e\u5b9a\uff09\u3002<\/p>\n<h3><a name=\"t2\"><\/a>Direct I\/O\u548cBuffered I\/O<\/h3>\n<p>&nbsp;<\/p>\n<p>Linux\u5728\u8fdb\u884cI\/O\u64cd\u4f5c\u7684\u65f6\u5019\u4f1a\u5148\u628a\u6570\u636e\u653e\u5230PageCache\u4e2d\u7136\u540e\u901a\u8fc7\u201c\u5185\u5b58\u6620\u5c04\u201d\u7684\u65b9\u5f0f\u8fd4\u56de\u7ed9\u5e94\u7528\u7a0b\u5e8f\uff0c\u8fd9\u6837\u505a\u7684\u597d\u5904\u662f\u53ef\u4ee5\u9884\u8bfb\u6570\u636e\u4e5f\u80fd\u5728\u591a\u4e2a\u8fdb\u7a0b\u8bfb\u53d6\u76f8\u540c\u6570\u636e\u7684\u65f6\u5019\u8d77\u5230Cache\u7684\u4f5c\u7528\u3002\u5e94\u7528\u7a0b\u5e8f\u4e0d\u80fd\u76f4\u63a5\u4f7f\u7528PageCache\u4e2d\u7684\u6570\u636e\uff0c\u901a\u5e38\u662f\u590d\u5236\u5230\u4e00\u5757\u201c\u7528\u6237\u7a7a\u95f4\u201d\u7684\u5185\u5b58\u4e2d\u518d\u4f7f\u7528\u3002<\/p>\n<ul>\n<li>\n<p class=\"no-text-indent\">Direct I\/O\u662f\u6307\u6570\u636e\u4e0d\u843d\u5728PageCache\uff0c\u76f4\u63a5\u4ece\u8bbe\u5907\u8bfb\u53d6\u5230\u6570\u636e\u540e\u653e\u5230\u7528\u6237\u7a7a\u95f4\u4e2d<\/p>\n<\/li>\n<li>\n<p class=\"no-text-indent\">Buffered I\/O\u662f\u6307\u6570\u636e\u7ade\u8d2dPageCache<\/p>\n<\/li>\n<\/ul>\n<p>\u540c\u6b65I\/O\u53ea\u80fd\u4f7f\u7528Buffered I\/O\uff1b\u5f02\u6b65\u963b\u585eI\/O\u53ef\u4ee5Buffered I\/O\u4e5f\u53ef\u4ee5\u4f7f\u7528Direct I\/O\uff1b\u5f02\u6b65\u975e\u963b\u585eI\/O\u53ea\u80fd\u4f7f\u7528Direct I\/O<\/p>\n<h3><a name=\"t3\"><\/a>Zero Copy<\/h3>\n<p>&nbsp;<\/p>\n<p>\u8003\u8651\u4ece\u78c1\u76d8\u8bfb\u53d6\u6587\u4ef6\u7ecf\u8fc7\u7f51\u5361\u53d1\u9001\u51fa\u53bb\uff0c\u4f1a\u6709\u00a0\u56db\u6b21\u5185\u5b58\u590d\u5236\u00a0\uff1a1. DMA\u4f1a\u590d\u5236\u78c1\u76d8\u6570\u636e\u5230\u5185\u6838\u7a7a\u95f4\uff0c2. \u5e94\u7528\u7a0b\u5e8f\u590d\u5236\u5185\u6838\u7a7a\u95f4\u7684\u6570\u636e\u5230\u7528\u6237\u7a7a\u95f4\uff1b3. \u5e94\u7528\u7a0b\u5e8f\u7528\u6237\u7a7a\u95f4\u7684\u6570\u636e\u590d\u5236\u5230Socket\u7f13\u51b2\uff08\u5185\u6838\u7a7a\u95f4\uff09\uff1b4. \u534f\u8bae\u6808\u628a\u6570\u636e\u590d\u5236\u5230\u7f51\u5361\u7684\u4e2d\u53d1\u9001\u3002\u00a0\u7b80\u5355\u6765\u8bf4Zero Copy\u5c31\u662f\u00a0\u8282\u7701\u8fd9\u4e2a\u8fc7\u7a0b\u4e2d\u7684\u5185\u5b58\u590d\u5236\u6b21\u6570\u00a0\u3002\u6709\u51e0\u79cd\u505a\u6cd5\uff1a<\/p>\n<ul>\n<li>\n<p class=\"no-text-indent\">Direct I\/O\u76f4\u63a5\u628a\u78c1\u76d8\u6570\u636e\u590d\u5236\u5230\u5185\u6838\u7a7a\u95f4\uff1b\u00a0\u4f46\u662fDirect I\/O\u6ca1\u6709\u529e\u6cd5\u76f4\u63a5\u628a\u6570\u636e\u653e\u5230\u7f51\u5361\u4e2d\u2014\u2014\u5fc5\u987b\u8981\u7ecf\u8fc7\u534f\u8bae\u6808\u00a0\u3002\u6240\u4ee5\u53ef\u4ee5\u8282\u7701\u4e00\u6b21\u5185\u5b58\u590d\u5236\uff1b<\/p>\n<\/li>\n<li>\n<p class=\"no-text-indent\">sendfile\uff0c\u78c1\u76d8\u6570\u636e\u901a\u8fc7DMA\u8bfb\u53d6\u5230\u5185\u6838\u7a7a\u95f4\u540e\u76f4\u63a5\u4ea4\u7ed9TCP\/IP\u534f\u8bae\u6808\uff1b\u771f\u6b63\u7684\u4e0d\u9700\u8981\u5185\u5b58\u590d\u5236\uff1b<\/p>\n<\/li>\n<\/ul>\n<p>\u9664\u6b64\u4e4b\u5916\u8fd8\u53ef\u4ee5\u5229\u7528\u00a0<code>splice<\/code>\u00a0\u3001\u00a0<code>mmap<\/code>\u00a0\u505a\u4e00\u4e9b\u4f18\u5316\uff0c\u6839\u636e\u4e0d\u540c\u7684\u8bbe\u5907\u9700\u8981\u91c7\u7528\u4e0d\u540c\u7684\u65b9\u5f0f\u6b64\u5904\u4e0d\u518d\u5c55\u5f00\u3002<\/p>\n<\/div>\n<\/div>\n<\/article>\n","protected":false},"excerpt":{"rendered":"<p>\u900f\u5f7b Linux (Unix) \u4e94\u79cd I<\/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":[],"tags":[118],"class_list":["post-1209","post","type-post","status-publish","format-standard","hentry","tag-02-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/1209","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=1209"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/1209\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=1209"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=1209"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=1209"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}