{"id":976,"date":"2013-08-07T20:01:31","date_gmt":"2013-08-07T12:01:31","guid":{"rendered":"http:\/\/www.dogeye.net\/?p=976"},"modified":"2013-08-07T20:01:31","modified_gmt":"2013-08-07T12:01:31","slug":"epoll%e5%ad%a6%e4%b9%a0%e6%8a%a5%e5%91%8a","status":"publish","type":"post","link":"https:\/\/ykyi.net\/?p=976","title":{"rendered":"epoll\u5b66\u4e60\u62a5\u544a"},"content":{"rendered":"<div>\n<p>&nbsp;epoll\u5b66\u4e60\u62a5\u544a<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;kamuszhou&nbsp;\u5468\u9704&nbsp;Jul\/26\/2013<\/p>\n<p>&nbsp;<\/p>\n<p>\u8fd9\u51e0\u5929\u901a\u8bfb\u4e86\u5185\u6838\u4e2d\u5bf9epoll&nbsp;I\/O\u6a21\u578b\u7684\u5b9e\u73b0\u4ee3\u7801\uff0c\u7ed3\u5408\u7f51\u7edc\u4e0a\u5f88\u591a\u4ecb\u7ecdepoll\u7684\u6587\u7ae0\uff0c\u5bf9epoll\u7684\u5b9e\u73b0\u539f\u7406\u5df2\u7ecf\u5f88\u719f\u6089\uff0c\u4e0b\u9762\u8c08\u8c08\u6211\u7684\u51e0\u70b9\u4f53\u4f1a\u3002\u4e0b\u6587\u5f15\u7528\u7684\u5185\u6838\u4ee3\u7801\u6765\u81ea3.9.6\u7248\u672c\u7684\u5185\u6838\uff0c\u89c1URL\uff1a<a href=\"http:\/\/lxr.oss.org.cn\/source\/fs\/eventpoll.c\">http:\/\/lxr.oss.org.cn\/source\/fs\/eventpoll.c<\/a>\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>\u4e00.&nbsp;epoll\u7684\u8fb9\u6cbf\u89e6\u53d1(ET)\u7684\u6548\u7387\u9ad8\u4e8e\u7535\u5e73(LT)\u89e6\u53d1\u7684\u6548\u7387<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;\u9996\u5148\u7b80\u5355\u4ecb\u7ecd\u4e00\u4e2a\u80cc\u666f\uff1aepoll\u5b9e\u73b0\u4e2d\uff0c\u628a\u5df2\u7ecf\u6709\u4e8b\u4ef6\u53d1\u751f\u7684\u6587\u4ef6\u7528\u4e00\u4e2a\u53cc\u94fe\u8868\u94fe\u63a5\u4e00\u8d77\uff0c\u8fd9\u4e2a\u53cc\u94fe\u8868\u662f\u5728struct&nbsp;eventpoll\u7ed3\u6784\u4e2d\u7684rdllist\u57df\u3002\u7528\u6237\u7a7a\u95f4\u8c03\u7528epoll_wait()\uff0c\u9677\u5165\u5185\u6838\u540e\u5c31\u4f1a\u7acb\u5373\u68c0\u67e5\u8fd9\u4e2a\u53cc\u94fe\u8868\uff0c\u5982\u679c\u94fe\u8868\u4e2d\u975e\u7a7a\uff0c\u5c31\u901a\u8fc7\u6587\u4ef6\u7684poll()\u51fd\u6570\u8be2\u95ee\u6587\u4ef6\u6709\u65e0\u4e8b\u4ef6\u53d1\u751f\u3002\u5982\u679c\u6709\u4e8b\u4ef6\u53d1\u751f\u4e14\u662f\u7528\u6237\u5173\u5fc3\u7684\uff0c\u5c31\u4f1a\u5411\u7528\u6237\u7a7a\u95f4\u62a5\u544a\uff0c\u5426\u5219\u5c31\u7761\u7720\u3002<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;epoll\u7684\u5b9e\u73b0\u4ee3\u7801\u4e2d\u5b9e\u9645\u4e0a\u53ea\u6709\u4e24\u884c\u4ee3\u7801\u4e0e\u89e6\u53d1\u65b9\u5f0f\u6709\u5173\uff0c\u5982\u4e0b\u56fe\u6240\u793a\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" height=\"265\" src=\"file:\/\/\/C:\\Users\\KAMUSZ~1\\AppData\\Local\\Temp\\ksohtml\\wps_clip_image-17809.png\" width=\"554\" \/><\/p>\n<p>&nbsp;\u4e0a\u56fe\u6240\u793a\u7684\u4ee3\u7801\u8fd0\u884c\u7684\u4e0a\u4e0b\u6587\u60c5\u51b5\u662f\uff1a\u7528\u6237\u52a0\u5165\u5230epoll\u4e2d\u7684\u67d0\u4e2a\u6587\u4ef6\uff0c\u53ea\u8981\u652f\u6301poll()\uff0c(\u53ef\u4ee5\u662fsocket\uff0cFIFO\uff0c\u88f8\u8bbe\u5907\uff0cwhatever)\u6709\u5173\u5fc3\u7684\u4e8b\u4ef6\u5230\u8fbe(\u6216\u53ef\u8bfb\uff0c\u6216\u53ef\u5199\uff0c\u6216\u62a5\u9519)\uff0c\u5185\u6838\u7a7a\u95f4\u5df2\u7ecf\u628a\u53d1\u751f\u7684\u4e8b\u4ef6\u590d\u5236\u5230\u4e86\u7528\u6237\u7a7a\u95f4\uff0c\u4f46\u8fd8\u6ca1\u6709\u4ece\u5185\u6838\u6001\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u3002\u5728\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u4e4b\u524d\u4ee3\u7801\u68c0\u67e5\u7528\u88abepoll\u76d1\u89c6\u7684\u8fd9\u4e2a\u6587\u4ef6\u662f\u5426\u662fET\u89e6\u53d1\uff0c\u5982\u679c\u4e0d\u662f(\u90a3\u5c31\u662fLT),\u5c31\u628a\u76d1\u89c6\u7684\u6587\u4ef6\u91cd\u65b0\u653e\u56de\u5c31\u7eea\u961f\u5217\uff0c\u4e0b\u6b21epoll_wait()\u8c03\u7528\u7684\u65f6\u5019\u4f1a\u7acb\u5373\u91cd\u65b0\u68c0\u67e5\u8fd9\u4e2a\u6587\u4ef6\u6709\u5426\u6709\u4e8b\u4ef6\u5230\u8fbe\u3002\u5982\u679c\u8fd9\u6587\u4ef6\u7684\u786e\u6709\u4e8b\u4ef6\u53d1\u751f\uff0c\u5219epoll_wait()\u62a5\u544a\u7ed9\u8c03\u7528\u8005\u3002\u5982\u679c\u6ca1\u6709\uff0c\u800c\u4e14\u5176\u5b83\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\u4e5f\u6ca1\u6709\u4e8b\u4ef6\u53d1\u751f\uff0c\u5219\u8c03\u7528epoll_wait()\u7684task\u5c31\u8ba9\u51fa\u5904\u7406\u5668\uff0c\u5f00\u59cb\u7761\u89c9(TASK_INTERRUPTIBLE)\u3002\u8fd9\u6bb5\u903b\u8f91\u5728static&nbsp;int&nbsp;ep_poll(struct&nbsp;eventpoll&nbsp;*ep,&nbsp;struct&nbsp;epoll_event&nbsp;__user&nbsp;*events,&nbsp;int&nbsp;maxevents,&nbsp;long&nbsp;timeout)\u4e2d\uff0c\u7b2c1494\u884c\u3002<\/p>\n<p>\u5982\u679c\u76d1\u542c\u7684\u6587\u4ef6\u5f00\u542f\u7684\u662f\u8fb9\u6cbf\u89e6\u53d1(\u9ed8\u8ba4)\uff0c\u5219\u4e0d\u4f1a\u6267\u884c\u4e0a\u56fe\u4e2d\u7684list_add_tail()\u903b\u8f91\u3002\u8fd9\u5c31\u662f\u8fb9\u6cbf\u89e6\u53d1\u53ea\u4f1a\u5411\u7528\u6237\u62a5\u544a\u4e00\u6b21\uff0c\u76f4\u5230\u4e0b\u4e00\u4e2a\u5173\u5fc3\u4e8b\u4ef6\u53d1\u751f\u624d\u5411\u7528\u6237\u7a7a\u95f4\u62a5\u544a\u7684\u539f\u56e0\u3002<\/p>\n<p>\u90a3\u4e48\u4e3a\u4ec0\u4e48ET\u89e6\u53d1\u6548\u7387\u9ad8\u4e8eLT\u89e6\u53d1\u5462\uff1f\u770b\u4e00\u4e2a\u4f8b\u5b50\uff0c\u5047\u5982\u5ba2\u6237\u7aef\u76d1\u89c6\u4e00\u4e2aTCP\u7684Socket\uff0c\u670d\u52a1\u7aef\u8fd9\u65f6\u53d1\u67651M\u6570\u636e\uff0c\u5ba2\u6237\u7aef\u7684\u4e3b\u673a\u7f51\u5361\u9a71\u52a8\u7f13\u5b58\u8db3\u591f\u5927\uff0c\u4e00\u6b21\u6027\u63a5\u6536\u5230\u4e86\u6240\u67091M\u6570\u636e\u3002\u4e0b\u9762\u770b\u4e24\u6bb5\u5ba2\u6237\u7aef\u7684\u63a5\u6536\u4f2a\u4ee3\u7801(\u6ca1\u6709\u5199read\u8c03\u7528\u8fd4\u56de\u65f6socket\u88ab\u5173\u95ed\u7684\u60c5\u51b5\uff1b\u53e6socket\u63cf\u8ff0\u7b26fd\u88ab\u8bbe\u4e3a\u975e\u963b\u585e)\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" height=\"164\" src=\"file:\/\/\/C:\\Users\\KAMUSZ~1\\AppData\\Local\\Temp\\ksohtml\\wps_clip_image-26818.png\" width=\"487\" \/><\/p>\n<p>&nbsp;&nbsp;&nbsp;\u4e0a\u56fe\u7684\u4ee3\u7801\u4f7f\u7528\u4e86LT\u89e6\u53d1\uff0c\u8fd9\u6bb5\u4ee3\u7801\u4f9d\u8d56epoll_wait()\u901a\u77e5\u8fd8\u6709\u6570\u636e\u53ef\u4f9b\u8bfb\u53d6\u3002\u6240\u4ee5\u5171\u8c03\u7528\u4e861024\u6b21epoll_wait()\uff0c1024\u6b21read()\uff0c\u51712048\u6b21\u7cfb\u7edf\u8c03\u7528\u624d\u8bfb\u5b8c1M\u6570\u636e\u3002<\/p>\n<p>&nbsp;<img loading=\"lazy\" decoding=\"async\" height=\"242\" src=\"file:\/\/\/C:\\Users\\KAMUSZ~1\\AppData\\Local\\Temp\\ksohtml\\wps_clip_image-31492.png\" width=\"496\" \/><\/p>\n<p>\u4e0a\u56fe\u4f7f\u7528ET\u89e6\u53d1\uff0cepoll_wait()\u53ea\u62a5\u544a\u4e00\u6b21\uff0c\u7136\u540e\u4ee3\u7801\u5faa\u73af\u8c03\u75281024\u6b21read()\u8bfb\u5b8c\u6570\u636e\uff0c\u76f4\u5230\u7b2c1025\u6b21read()\u8fd4\u56de-1\uff0c\u51fa\u9519\u7801\u4e3aEAGAIN(EAGAIN\u7b49\u4e8eEWOULDBLOCK)\uff0c\u4e8e\u662f\u4ee3\u7801\u77e5\u9053\u5df2\u7ecf\u63a5\u6536\u5b8c\u6570\u636e\u3002\u4e00\u5171\u53ea\u4f7f\u7528\u4e861026\u6b21\u7cfb\u7edf\u8c03\u7528\u5c31\u8bfb\u5b8c\u4e86\u6570\u636e\u3002<\/p>\n<p>\u603b\u7ed3\uff1a\u5373\u4f7f\u4f7f\u7528\u7535\u5e73\u89e6\u53d1\u4e5f\u4e0d\u8981\u4f9d\u8d56epoll_wait()\u901a\u77e5\u8c03\u7528\u8005\u5230\u8fbe\u4e8b\u4ef6\uff0c\u9700\u8981\u5faa\u73af\u8c03\u7528IO\u51fd\u6570\u76f4\u5230\u88ab\u901a\u77e5EAGAIN\uff0c\u8fd9\u6837\u5c31\u628aepoll_wait()\u7684\u8c03\u7528\u6b21\u6570\u964d\u5230\u6700\u4f4e\uff0c\u4ec5\u7ba1\u6709\u53ef\u80fd\u5728\u4e0b\u6b21epoll_wait()\u65f6\u4f1a\u6709\u53ef\u80fd\u6d6a\u8d39\u4e00\u6b21\u6587\u4ef6\u7684poll()\u8c03\u7528\uff0c\u4f46\u8fd9\u4e2a\u5f88\u5c0f\u7684\u5f00\u9500\u53ef\u4ee5\u5ffd\u7565\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>\u4e8c.&nbsp;\u4e3a\u4ec0\u4e48epoll\u652f\u6301\u5d4c\u5957\u8c03\u7528<\/p>\n<p>\u8bfbepoll\u7684\u5b9e\u73b0\u4ee3\u7801\u53d1\u73b0\uff0c\u4e00\u4e2aepoll\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26epfd\u53ef\u4ee5\u5d4c\u5957\u7684\u52a0\u5165\u53e6\u4e00\u4e2aepoll\u3002\u8fd9\u6837\u6709\u4ec0\u4e48\u7528\u5462\uff1f<\/p>\n<p>epoll\u7684\u5b9e\u73b0\u4e2d&ldquo;\u5e73\u7b49\u7684&rdquo;\u5bf9\u5f85\u6bcf\u4e2a\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\uff0c\u5b83\u4eec\u7ef4\u62a4\u5728\u4e00\u68f5\u7ea2\u9ed1\u6811\u4e4b\u4e2d\uff0c\u5047\u5982\u6709\u5341\u4e07\u4e2a\u6587\u4ef6\u88ab\u76d1\u89c6\uff0c\u90a3\u4e48\u67e5\u627e\u67d0\u4e2a\u6587\u4ef6\u65f6\u5c31\u8981\u5728\u8fd9\u5341\u4e07\u4e2a\u6587\u4ef6\u4e2d\u67e5\u627e\u3002\u5373\u4f7f\u7ea2\u9ed1\u6811\u7684\u67e5\u627e\u6548\u7387\u662flog(n)\uff0c\u6587\u4ef6\u975e\u5e38\u5927\u65f6\u4e5f\u662f\u6bd4\u8f83\u6d88\u8017\u65f6\u95f4\u7684\u3002<\/p>\n<p>\u90a3\u4e48\u5047\u5982\u6709\u8fd9\u6837\u4e00\u79cd\u60c5\u51b5\uff0c\u5982\u679c\u8fd9\u5341\u4e07\u4e2a\u6587\u4ef6\u4e2d\u53ea\u67091000\u4e2a\u662f\u6d3b\u8dc3\u7684\uff0c\u6216\u8005\u8bf4\u8fd91000\u4e2a\u6587\u4ef6\u4f18\u5148\u7ea7\u6700\u9ad8\u3002\u90a3\u4e48\u5219\u6709\u4e00\u79cd\u4f18\u5316\u65b9\u6848\u662f\uff0c\u521b\u5efa\u4e24\u4e2aepoll\uff0c\u7b2c\u4e00\u4e2aepoll\uff08epfd0\uff09\u76d1\u63a7100000&nbsp;&#8211;&nbsp;1000&nbsp;\u4e2a\u6587\u4ef6\uff0c\u7b2c\u4e8c\u4e2aepoll&nbsp;(epfd1)&nbsp;\u76d1\u63a71000\u4e2a\u9ad8\u4f18\u5148\u7ea7\u6587\u4ef6\u4ee5\u53caepfd0\u3002\u8fd9\u6837\u7684\u597d\u5904\u662f\uff0c\u5927\u591a\u6570\u60c5\u51b5\u4e0bepoll\u5b9e\u73b0\u53ea\u57281001\u4e2a\u5143\u7d20\u7684\u7ea2\u9ed1\u6811\u4e2d\u67e5\u627e\uff0c\u81ea\u7136\u6548\u7387\u63d0\u9ad8\u4e86\u3002<\/p>\n<p>\u603b\u7ed3\uff1aepoll\u7684\u5d4c\u5957\u8c03\u7528\u7ed9\u5f00\u53d1\u8005\u63d0\u4f9b\u4e86\u4e00\u4e2a\u5728\u9ad8\u5e76\u53d1\u73af\u5883\u4e0b\u7684\u4f18\u5316\u65b9\u6848\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>\u4e09.&nbsp;epoll\u7684\u6548\u7387\u4e00\u5b9a\u6bd4select\/poll\u9ad8\u5417\u3002<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;\u7b54\u6848\u662f\u4e0d\u4e00\u5b9a\u3002<\/p>\n<p>Select\u7684\u7f3a\u70b9\u5927\u81f4\u6709\uff1a<\/p>\n<p>1.&nbsp;\u5185\u6838\u4e2d\u5199\u6b7b\u4e86\u6700\u591a\u53ea\u80fd\u76d1\u89c61024\u4e2a\u6587\u4ef6.<\/p>\n<p>2.&nbsp;\u6bcf\u6b21\u8c03\u7528select\u90fd\u8981\u628a\u5173\u5fc3\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u548c\u5173\u5fc3\u7684\u6587\u4ef6\u4ef6\u4ece\u4e00\u4e2a\u7528\u6237\u7a7a\u95f4\u7684\u957f\u957f\u7684\u6570\u7ec4\u62f7\u8d1d\u5230\u5185\u6838\u7a7a\u95f4.<\/p>\n<p>3.&nbsp;select\u82e5\u4f7f\u5f97caller\u8fdb\u7a0b\u8fdb\u5165\u7761\u7720\u540e\uff0c\u67d0\u4e2a\u6587\u4ef6\u6709\u4e8b\u4ef6\u5230\u8fbe\u6b64\u8fdb\u7a0b\u88ab\u5524\u9192\uff0c\u90a3\u4e48\u6240\u6709\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\u5168\u90e8\u4f1a\u88ab\u8c03\u7528poll()\u8be2\u95ee&ldquo;\u4f60\u6709\u6ca1\u6709\u4e8b\u4ef6\u5230\u8fbe&rdquo;\uff0c\u8fd9\u662f\u4e00\u4e2a\u7ebf\u6027\u7684\u65f6\u95f4\u590d\u6742\u5ea6\u3002<\/p>\n<p>epoll\u9488\u5bf9select\u7684\u4e09\u4e2a\u7f3a\u70b9\u7684\u6539\u8fdb\uff1a<\/p>\n<p>1.&nbsp;\u76d1\u89c6\u7684\u6587\u4ef6\u6570\u7531\u53d6\u51b3\u4e8e\u7cfb\u7edf\u4e2d\u6709\u591a\u5c11\u4f4e\u7aef\u5185\u5b58(x86_64\u67b6\u6784\u4e2d\u7684\u6240\u6709\u5185\u5b58\u90fd\u662f\u4f4e\u7aef\u5185\u5b58)\u30023.9.6\u7248\u672c\u7684\u5185\u6838\u5b9e\u73b0\u4e2d\uff0c\u5bf9\u4e8e\u6bcf\u4e2a\u767b\u5f55\u7528\u6237\uff0c\u6700\u591a\u4f7f\u7528\u7cfb\u7edf\u4e2d\u4f4e\u7aef\u5185\u5b58\u76844%\u7528\u6765\u521b\u5efa\u76d1\u89c6\u7528\u7684\u6570\u636e\u7ed3\u6784\u3002\u89c1\u7b2c1951\u884c\u4ee3\u7801\u3002max_user_watches&nbsp;=&nbsp;(((si.totalram&nbsp;&#8211;&nbsp;si.totalhigh)&nbsp;\/&nbsp;25)&nbsp;&lt;&lt;&nbsp;PAGE_SHIFT)&nbsp;\/&nbsp;EP_ITEM_COST;<\/p>\n<p>2.&nbsp;\u7528\u6237\u53ea\u9700\u8981\u628a\u5173\u5fc3\u7684\u6587\u4ef6\u5bf9\u5e94\u7684\u6570\u636e\u7ed3\u6784\u5728\u8c03\u7528epoll_wait()\u524d\u7528epoll_ctl()\u4e00\u6b21\u6027\u4f20\u5165\u5185\u5b58\uff0c\u4ee5\u540e\u8c03\u7528epoll_wait()\u65f6\u4e0d\u9700\u8981\u50cfselect\u4e00\u6837\u62f7\u8d1d\u5927\u91cf\u6570\u636e\u3002<\/p>\n<p>3.&nbsp;\u5f53\u8c03\u7528epoll_wait()\u7684caller\u8fdb\u7a0b\u7761\u7720\u65f6\uff0c\u7a81\u7136\u6709\u4e8b\u4ef6\u5230\u8fbe\uff0ccaller\u8fdb\u7a0b\u88ab\u5524\u9192\uff0cepoll_wait()\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\uff0c\u5185\u6838\u5e76\u4e0d\u904d\u5386\u6ca1\u6709\u76d1\u89c6\u7684\u6587\u4ef6\uff0c\u800c\u53ea\u62a5\u544a\u5728\u4e00\u4e2a\u5373\u77ed\u65f6\u95f4\u5185\u53d1\u751f\u7684\u4e8b\u4ef6\u3002\u4e0b\u9762\u66f4\u8be6\u7ec6\u7684\u63cf\u8ff0\u8fd9\u4e2a\u573a\u666f\uff0c\u4ee5\u76d1\u89c6tcp&nbsp;socket\u4e3e\u4f8b\uff0c\u5927\u81f4\u662f\uff1a\u67d0\u8fdb\u7a0b\u8c03\u7528epoll_wait()\uff0c\u6b64\u65f6\u6ca1\u6709\u4efb\u4f55\u5b83\u5173\u5fc3\u7684\u4e8b\u4ef6\u53d1\u751f\uff0c\u4e8e\u662fcaller\u8fdb\u7a0b\u8fdb\u5165\u7761\u7720\u3002\u5904\u7406\u5668\u8c03\u5ea6\u4e86\u5176\u5b83\u8fdb\u7a0b\u3002\u6570\u636e\u5230\u8fbe\u65f6\uff0c\u5f53\u524d\u8fdb\u7a0b\u88ab\u786c\u4ef6\u4e2d\u65ad\uff0c\u7f51\u5361\u9a71\u52a8\u6536\u5230\u6570\u636e\u5305\uff0c\u6570\u636e\u5305\u5728\u4e2d\u65ad\u5904\u7406\u51fd\u6570\u4e2d\u88ab\u62f7\u5165\u5185\u6838\uff0c\u4e2d\u65ad\u5904\u7406\u51fd\u6570\u8bbe\u7f6e\u4e2d\u65ad\u4e0b\u534a\u90e8(Half&nbsp;Bottom)\u3002\u4e0b\u534a\u90e8\u88ab\u5904\u7406\u5668\u8c03\u5ea6\uff0c\u8c03\u7528epoll\u5b9e\u73b0\u4ee3\u7801\u6ce8\u518c\u7684\u56de\u8c03\u51fd\u6570ep_poll_callback()\u3002ep_poll_callback()\u51fd\u6570\u5524\u9192\u4e4b\u524d\u7684caller\u8fdb\u7a0b\uff0ccaller\u8fdb\u7a0b\u91cd\u65b0\u83b7\u5f97CPU\uff0c\u4eceepoll\u5b9e\u73b0\u7684ep_poll()\u51fd\u6570\u4e2d\u6062\u590d\u6267\u884c\uff0c\u57283.9.6\u5185\u6838\u4e2d\u7684\u7b2c1564\u884c\uff1a&nbsp;if&nbsp;(!schedule_hrtimeout_range(to,&nbsp;slack,&nbsp;HRTIMER_MODE_ABS))\u3002\u7136\u540e\uff0c\u5185\u6838\u4ee3\u7801\u5f00\u59cb\u6536\u96c6\u5df2\u7ecf\u5c31\u7eea\u7684\u6587\u4ef6\u548c\u53d1\u751f\u7684\u4e8b\u4ef6\uff0c\u53d1\u56de\u7528\u6237\u7a7a\u95f4\u3002\u53ea\u6709\u4ece\u7b2c\u4e00\u6b21\u56de\u8c03\u51fd\u6570ep_poll_callback()\u88ab\u9a71\u52a8\u7684\u4ee3\u7801\u8c03\u7528\uff08caller\u8fdb\u7a0b\u8fd8\u5728\u7761\u7720\u65f6\u6267\u884c\u7684ep_poll_callback()\u7b97\u7b2c\u4e00\u6b21\uff09\u5230epoll\u5b9e\u73b0\u4ee3\u7801\u8d70\u5230\u7b2c586\u884c\u5173\u95ed\u4e2d\u65ad\u5173\u95ed\u4e2d\u65ad\u7684\u4ee3\u7801&nbsp;spin_lock_irqsave(&amp;ep-&gt;lock,&nbsp;flags);\u4e4b\u95f4\u53d1\u751f\u7684\u4e8b\u4ef6\u624d\u4f1a\u88ab\u6536\u96c6\u3002<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;\u5bf9\u4e8e\u7b2c3\u70b9\uff0c\u8fd9\u662fepoll\u7684\u4f18\u70b9\uff0c\u4f46\u5728\u67d0\u79cd\u60c5\u51b5\u4e0b\u5374\u4f1a\u662fepoll\u7684\u7f3a\u70b9\u3002\u7f51\u4e0a\u5f88\u591a\u6bd4\u8f83poll,&nbsp;select,&nbsp;epoll\u6027\u80fd\u7684\u6587\u7ae0\uff0c\u6ca1\u6765\u5f97\u53ca\u4ed4\u7ec6\u770b\uff0c\u6211\u4e2a\u4eba\u8ba4\u4e3a\u7ed3\u8bba\u662f\u53ef\u9760\u7684\u3002\u7ed3\u8bba\u5f15\u5165\u4e86\u4e00\u4e2a\u6982\u5ff5active-to-total&nbsp;ratio\uff0c\u8bbe\u6240\u6709\u88ab\u76d1\u63a7\u7684\u6587\u4ef6\u6570\u662fn\uff0c\u6d3b\u8dc3\u7684\u6587\u4ef6\u6570\u662fm\uff0cactive-to-total\u6bd4\u5219\u662fm\/n\uff0c\u5982\u679c\u8fd9\u4e2a\u6bd4\u975e\u5e38\u9ad8\uff0c\u6bd4\u5982\u5927\u4e8e0.7\uff0c\u5219poll\u6216select\u7684\u6027\u80fd\u8981\u9ad8\u8fc7epoll\uff0c\u53cd\u4e4b\u5219epoll\u80dc\u51fa\u3002<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;\u5bf9\u6bd4\u524d\u6587\u5bf9select\u7684\u7b2c3\u4e2a\u7f3a\u70b9\u548cepoll\u7684\u6539\u8fdb\u70b93\u7684\u53d9\u8ff0\u53ef\u4ee5\u89e3\u91ca\u8fd9\u4e2a\u539f\u56e0\u3002\u56e0\u4e3aselect\u5728\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u524d\u53c8\u8f6e\u5faa\u4e86\u6240\u6709\u5173\u5fc3\u7684\u6587\u4ef6\uff0c\u800c\u8fd9\u4e9b\u6587\u4ef6\u53c8\u5927\u90e8\u5206\u662f\u6709\u4e8b\u4ef6\u53d1\u751f\u7684\uff0c\u6240\u4ee5select\u6240\u505a\u7684\u5de5\u4f5c\u5e76\u6ca1\u6709\u6d6a\u8d39\uff0c\u4f46epoll\u53ea\u6536\u96c6\u4e86\u4e00\u5c0f\u6bb5\u65f6\u95f4\u4e2d\u53d1\u751f\u7684\u4e8b\u4ef6\uff0c\u4e8e\u662fselect\u8f83\u4e4bepoll\u51cf\u5c11\u4e86\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u7684\u9891\u7e41\u5207\u6362\uff0c\u4ece\u800c\u8ba9select\u7684\u6027\u80fd\u53cd\u8d85epoll\u3002<\/p>\n<p>\u90a3\u4e48\u5982\u4f55\u6539\u8fdb\u5462\uff1f\u660e\u767d\u4e86\u4ee5\u4e0a\u7684\u539f\u56e0\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u5bf9epoll\u505a\u51fa\u6539\u8fdb\uff0c\u7406\u8bba\u4e0a\u5bf9\u4e8eactive-to-total\u6bd4\u8f83\u9ad8\u7684\u5e94\u7528\u73af\u5883\u4e0b\uff0c\u53ef\u4ee5\u5728epoll\u7684\u5b9e\u73b0\u4e2d\u52a0\u5165\u4e0eselect\u505a\u6cd5\u76f8\u540c\u903b\u8f91\uff0c\u5373\u9000\u51fa\u524d\u8be2\u95ee\u6240\u6709\u7684\u76d1\u63a7\u6587\u4ef6\uff0c\u53cd\u6b63active-to-total\u6bd4\u5f88\u9ad8\u3002\u6216\u8005\u66f4\u597d\u7684\u65b9\u6848\uff0c\u7528\u4e00\u4e2a\u94fe\u8868\u94fe\u63a5\u6d3b\u8dc3\u7684\u6587\u4ef6\uff0c\u5728epoll\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u524d\u904d\u5386\u8fd9\u4e2a\u94fe\u8868\uff0c\u4e89\u53d6\u6bcf\u4e00\u4e2aepoll_wait()\u8c03\u7528\u8fd4\u56de\u5c3d\u53ef\u80fd\u591a\u7684\u4e8b\u4ef6\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>\u9644\uff1aepoll\u7684\u4e3b\u8981\u6570\u636e\u7ed3\u6784\u7b80\u4ecb.<\/p>\n<p>epoll\u63a5\u53e3\u7684\u4e3b\u8981\u6570\u636e\u7ed3\u6784\u6709struct&nbsp;eventpoll\uff0cstruct&nbsp;epitem\uff0cstruct&nbsp;eppoll_entry\u3002<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;\u5728\u8bb2\u8ff0\u8fd9\u4e09\u4e2a\u6570\u636e\u7ed3\u6784\u524d\u5148\u63d0\u4e00\u4e0bstruct&nbsp;file\u3002Unix\u8bbe\u8ba1\u521d\u671f\u5e0c\u671b\u5b83\u7684\u8bbe\u8ba1\u9075\u4ece&ldquo;\u4e00\u5207\u7686\u6587\u4ef6&rdquo;\u7684\u7406\u5ff5\u3002\u5728Linux\u5185\u6838\u4e2d\uff0c\u6bcf\u4e2a\u62bd\u8c61\u7684\u6587\u4ef6\u5bf9\u5e94\u4e00\u4e2a\u5185\u6838struct&nbsp;file\u7ed3\u6784\u4f53\u3002Struct&nbsp;file\u7ed3\u6784\u4f53\u4e2d\u6709\u4e00\u4e2avoid&nbsp;*private_data\u57df\u3002\u4e0d\u540c\u7684\u6587\u4ef6\u7c7b\u578b\u4f1a\u5728private_data\u57df\u4e2d\u5b58\u653e\u7279\u5b9a\u7684\u4fe1\u606f\u3002Struct&nbsp;file\u4e2d\u53e6\u4e00\u4e2a\u57dff_op\u662f\u51fd\u6570\u6307\u9488\u7684\u5217\u8868\uff0c\u5b83\u8bb0\u5f55\u4e86\u5bf9\u5e94\u8be5\u6587\u4ef6\u7684\u64cd\u4f5c\u3002\u6240\u6709epoll\u6587\u4ef6\u7684f_op\u90fd\u6307\u5411static&nbsp;const&nbsp;struct&nbsp;<a href=\"http:\/\/lxr.oss.org.cn\/ident?i=file_operations\">file_operations<\/a>&nbsp;<a href=\"http:\/\/lxr.oss.org.cn\/ident?i=eventpoll_fops\">eventpoll_fops<\/a>\uff0c\u56e0\u6b64\u53ef\u4ee5\u4ee3\u7801\u5224\u65ad\u4e00\u4e2a\u6587\u4ef6\u662f\u4e0d\u662fepoll\u5982\u4e0b\uff1a<\/p>\n<p>static&nbsp;inline&nbsp;int&nbsp;is_file_epoll(struct&nbsp;file&nbsp;*f)<\/p>\n<p>{<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;f-&gt;f_op&nbsp;==&nbsp;&amp;eventpoll_fops;<\/p>\n<p>}<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;\u6bcf\u6b21\u6210\u529f\u8c03\u7528epoll_create\u65f6\u5c31\u4f1a\u521b\u5efa\u4e00\u4e2astruct&nbsp;file\u7684\u7ed3\u6784\u4f53\uff0c\u548c\u4e00\u4e2astruct&nbsp;eventpoll\u3002Struct&nbsp;file\u4e2d\u7684private_data\u6307\u5411struct&nbsp;eventpoll\u3002eventpoll\u7ef4\u62a4\u4e86\u8fd9\u4e2aepoll\u7684\u91cd\u8981\u4fe1\u606f\u3002\u5176\u4e2d\u6bd4\u8f83\u91cd\u8981\u7684\u51e0\u4e2a\u5b57\u6bb5\u6709\uff1a\u4e00\u4e2a\u5faa\u73af\u5217\u8868struct&nbsp;list_head&nbsp;&nbsp;rdllist\u94fe\u63a5\u4e86\u8be5epll\u4e2d\u5df2\u7ecf\u53ef\u4ee5\u8bfb\u5199\u6216\u8005\u6709\u51fa\u9519\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002\u4e00\u4e2a\u7ea2\u9ed1\u6811\u7684\u6839\u7ed3\u70b9struct&nbsp;rb_root&nbsp;&nbsp;rbr\uff0ceventpoll\u7ef4\u62a4\u4e86\u4e00\u68f5\u7ea2\u9ed1\u6811\uff0c\u6811\u4e2d\u7684\u7ed3\u70b9\u662fstruct&nbsp;epitem\u3002<\/p>\n<p>\u6bcf\u4e2a\u88ab\u52a0\u5165\u5230epoll\u4e2d\u88ab\u5173\u6ce8\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u90fd\u5bf9\u5e94\u4e00\u4e2astruct&nbsp;epitem\u7ed3\u6784\u4f53\u3002\u6240\u6709\u52a0\u5165\u5230\u540c\u4e00\u4e2aepoll\u4e2d\u5bf9\u5e94\u7684\u6240\u6709epitem\u90fd\u6302\u5728\u7ea2\u9ed1\u6811\u4e0a\u3002\u8be5\u7ea2\u9ed1\u6811\u7684\u6839\u7ed3\u6784\u4fdd\u5b58\u5728struct&nbsp;eventpoll\u4e2d\u3002epitem\u4e2d\u8bb0\u5f55\u4e86\u5bf9\u5e94\u7684\u6587\u4ef6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u548c\u6587\u4ef6\u6307\u9488\u3002<\/p>\n<p>struct&nbsp;eppoll_entry\u662f\u7528\u6765\u6302\u63a5\u5230\u8bbe\u5907\u6587\u4ef6\u4e2d\u7684\u7ed3\u6784\u4f53\u3002\u8bbe\u5907\u9a71\u52a8\u5728\u5f97\u77e5\u81ea\u5df1\u53ef\u8bfb\u6216\u53ef\u5199\u6216\u6709\u9519\u8bef\u65f6\u901a\u8fc7\u8fd9\u4e2a\u7ed3\u6784\u4f53\u901a\u77e5\u6709\u4e8b\u4ef6\u53d1\u751f\u3002\u6bcf\u4e2aeppoll_entry\u90fd\u6307\u5411\u4e00\u4e2aepitem\uff0c\u4e00\u4e2aepitem\u53ef\u80fd\u5bf9\u5e94\u591a\u4e2aeppoll_entry\u3002eppoll_entry\u4e2d\u7684\u57dfwait_queue_t&nbsp;&nbsp;wait\u5c31\u662f\u88ab\u7528\u6765\u6302\u63a5\u5230\u8bbe\u5907\u6587\u4ef6\u4e2d\u7684\u7b49\u5f85\u961f\u5217\u3002\u8bbe\u5907\u6587\u4ef6\u901a\u8fc7wait\u53ef\u4ee5\u62ff\u5230eppoll_entry\uff0c\u518d\u901a\u8fc7eppoll_entry\u62ff\u5230epitem\uff0c\u518d\u62ff\u5230eventpoll\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp;epoll\u5b66\u4e60\u62a5\u544a &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;kamuszhou&nbsp;\u5468\u9704&nbsp;Jul\/26\/2013 &nbsp; \u8fd9\u51e0\u5929\u901a\u8bfb\u4e86\u5185\u6838\u4e2d\u5bf9epoll&nbsp;I\/O\u6a21\u578b\u7684\u5b9e\u73b0\u4ee3\u7801\uff0c\u7ed3\u5408\u7f51\u7edc\u4e0a\u5f88\u591a\u4ecb\u7ecdepoll\u7684\u6587\u7ae0\uff0c\u5bf9epoll\u7684\u5b9e\u73b0\u539f\u7406\u5df2\u7ecf\u5f88\u719f\u6089\uff0c\u4e0b\u9762\u8c08\u8c08\u6211\u7684\u51e0\u70b9\u4f53\u4f1a\u3002\u4e0b\u6587\u5f15\u7528\u7684\u5185\u6838\u4ee3\u7801\u6765\u81ea3.9.6\u7248\u672c\u7684\u5185\u6838\uff0c\u89c1URL\uff1ahttp:\/\/lxr.oss.org.cn\/source\/fs\/eventpoll.c\u3002 &nbsp; \u4e00.&nbsp;epoll\u7684\u8fb9\u6cbf\u89e6\u53d1(ET)\u7684\u6548\u7387\u9ad8\u4e8e\u7535\u5e73(LT)\u89e6\u53d1\u7684\u6548\u7387 &nbsp;&nbsp;&nbsp;&nbsp;\u9996\u5148\u7b80\u5355\u4ecb\u7ecd\u4e00\u4e2a\u80cc\u666f\uff1aepoll\u5b9e\u73b0\u4e2d\uff0c\u628a\u5df2\u7ecf\u6709\u4e8b\u4ef6\u53d1\u751f\u7684\u6587\u4ef6\u7528\u4e00\u4e2a\u53cc\u94fe\u8868\u94fe\u63a5\u4e00\u8d77\uff0c\u8fd9\u4e2a\u53cc\u94fe\u8868\u662f\u5728struct&nbsp;eventpoll\u7ed3\u6784\u4e2d\u7684rdllist\u57df\u3002\u7528\u6237\u7a7a\u95f4\u8c03\u7528epoll_wait()\uff0c\u9677\u5165\u5185\u6838\u540e\u5c31\u4f1a\u7acb\u5373\u68c0\u67e5\u8fd9\u4e2a\u53cc\u94fe\u8868\uff0c\u5982\u679c\u94fe\u8868\u4e2d\u975e\u7a7a\uff0c\u5c31\u901a\u8fc7\u6587\u4ef6\u7684poll()\u51fd\u6570\u8be2\u95ee\u6587\u4ef6\u6709\u65e0\u4e8b\u4ef6\u53d1\u751f\u3002\u5982\u679c\u6709\u4e8b\u4ef6\u53d1\u751f\u4e14\u662f\u7528\u6237\u5173\u5fc3\u7684\uff0c\u5c31\u4f1a\u5411\u7528\u6237\u7a7a\u95f4\u62a5\u544a\uff0c\u5426\u5219\u5c31\u7761\u7720\u3002 &nbsp;&nbsp;&nbsp;&nbsp;epoll\u7684\u5b9e\u73b0\u4ee3\u7801\u4e2d\u5b9e\u9645\u4e0a\u53ea\u6709\u4e24\u884c\u4ee3\u7801\u4e0e\u89e6\u53d1\u65b9\u5f0f\u6709\u5173\uff0c\u5982\u4e0b\u56fe\u6240\u793a\u3002 &nbsp;\u4e0a\u56fe\u6240\u793a\u7684\u4ee3\u7801\u8fd0\u884c\u7684\u4e0a\u4e0b\u6587\u60c5\u51b5\u662f\uff1a\u7528\u6237\u52a0\u5165\u5230epoll\u4e2d\u7684\u67d0\u4e2a\u6587\u4ef6\uff0c\u53ea\u8981\u652f\u6301poll()\uff0c(\u53ef\u4ee5\u662fsocket\uff0cFIFO\uff0c\u88f8\u8bbe\u5907\uff0cwhatever)\u6709\u5173\u5fc3\u7684\u4e8b\u4ef6\u5230\u8fbe(\u6216\u53ef\u8bfb\uff0c\u6216\u53ef\u5199\uff0c\u6216\u62a5\u9519)\uff0c\u5185\u6838\u7a7a\u95f4\u5df2\u7ecf\u628a\u53d1\u751f\u7684\u4e8b\u4ef6\u590d\u5236\u5230\u4e86\u7528\u6237\u7a7a\u95f4\uff0c\u4f46\u8fd8\u6ca1\u6709\u4ece\u5185\u6838\u6001\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u3002\u5728\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u4e4b\u524d\u4ee3\u7801\u68c0\u67e5\u7528\u88abepoll\u76d1\u89c6\u7684\u8fd9\u4e2a\u6587\u4ef6\u662f\u5426\u662fET\u89e6\u53d1\uff0c\u5982\u679c\u4e0d\u662f(\u90a3\u5c31\u662fLT),\u5c31\u628a\u76d1\u89c6\u7684\u6587\u4ef6\u91cd\u65b0\u653e\u56de\u5c31\u7eea\u961f\u5217\uff0c\u4e0b\u6b21epoll_wait()\u8c03\u7528\u7684\u65f6\u5019\u4f1a\u7acb\u5373\u91cd\u65b0\u68c0\u67e5\u8fd9\u4e2a\u6587\u4ef6\u6709\u5426\u6709\u4e8b\u4ef6\u5230\u8fbe\u3002\u5982\u679c\u8fd9\u6587\u4ef6\u7684\u786e\u6709\u4e8b\u4ef6\u53d1\u751f\uff0c\u5219epoll_wait()\u62a5\u544a\u7ed9\u8c03\u7528\u8005\u3002\u5982\u679c\u6ca1\u6709\uff0c\u800c\u4e14\u5176\u5b83\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\u4e5f\u6ca1\u6709\u4e8b\u4ef6\u53d1\u751f\uff0c\u5219\u8c03\u7528epoll_wait()\u7684task\u5c31\u8ba9\u51fa\u5904\u7406\u5668\uff0c\u5f00\u59cb\u7761\u89c9(TASK_INTERRUPTIBLE)\u3002\u8fd9\u6bb5\u903b\u8f91\u5728static&nbsp;int&nbsp;ep_poll(struct&nbsp;eventpoll&nbsp;*ep,&nbsp;struct&nbsp;epoll_event&nbsp;__user&nbsp;*events,&nbsp;int&nbsp;maxevents,&nbsp;long&nbsp;timeout)\u4e2d\uff0c\u7b2c1494\u884c\u3002 \u5982\u679c\u76d1\u542c\u7684\u6587\u4ef6\u5f00\u542f\u7684\u662f\u8fb9\u6cbf\u89e6\u53d1(\u9ed8\u8ba4)\uff0c\u5219\u4e0d\u4f1a\u6267\u884c\u4e0a\u56fe\u4e2d\u7684list_add_tail()\u903b\u8f91\u3002\u8fd9\u5c31\u662f\u8fb9\u6cbf\u89e6\u53d1\u53ea\u4f1a\u5411\u7528\u6237\u62a5\u544a\u4e00\u6b21\uff0c\u76f4\u5230\u4e0b\u4e00\u4e2a\u5173\u5fc3\u4e8b\u4ef6\u53d1\u751f\u624d\u5411\u7528\u6237\u7a7a\u95f4\u62a5\u544a\u7684\u539f\u56e0\u3002 \u90a3\u4e48\u4e3a\u4ec0\u4e48ET\u89e6\u53d1\u6548\u7387\u9ad8\u4e8eLT\u89e6\u53d1\u5462\uff1f\u770b\u4e00\u4e2a\u4f8b\u5b50\uff0c\u5047\u5982\u5ba2\u6237\u7aef\u76d1\u89c6\u4e00\u4e2aTCP\u7684Socket\uff0c\u670d\u52a1\u7aef\u8fd9\u65f6\u53d1\u67651M\u6570\u636e\uff0c\u5ba2\u6237\u7aef\u7684\u4e3b\u673a\u7f51\u5361\u9a71\u52a8\u7f13\u5b58\u8db3\u591f\u5927\uff0c\u4e00\u6b21\u6027\u63a5\u6536\u5230\u4e86\u6240\u67091M\u6570\u636e\u3002\u4e0b\u9762\u770b\u4e24\u6bb5\u5ba2\u6237\u7aef\u7684\u63a5\u6536\u4f2a\u4ee3\u7801(\u6ca1\u6709\u5199read\u8c03\u7528\u8fd4\u56de\u65f6socket\u88ab\u5173\u95ed\u7684\u60c5\u51b5\uff1b\u53e6socket\u63cf\u8ff0\u7b26fd\u88ab\u8bbe\u4e3a\u975e\u963b\u585e)\u3002 &nbsp;&nbsp;&nbsp;\u4e0a\u56fe\u7684\u4ee3\u7801\u4f7f\u7528\u4e86LT\u89e6\u53d1\uff0c\u8fd9\u6bb5\u4ee3\u7801\u4f9d\u8d56epoll_wait()\u901a\u77e5\u8fd8\u6709\u6570\u636e\u53ef\u4f9b\u8bfb\u53d6\u3002\u6240\u4ee5\u5171\u8c03\u7528\u4e861024\u6b21epoll_wait()\uff0c1024\u6b21read()\uff0c\u51712048\u6b21\u7cfb\u7edf\u8c03\u7528\u624d\u8bfb\u5b8c1M\u6570\u636e\u3002 &nbsp; \u4e0a\u56fe\u4f7f\u7528ET\u89e6\u53d1\uff0cepoll_wait()\u53ea\u62a5\u544a\u4e00\u6b21\uff0c\u7136\u540e\u4ee3\u7801\u5faa\u73af\u8c03\u75281024\u6b21read()\u8bfb\u5b8c\u6570\u636e\uff0c\u76f4\u5230\u7b2c1025\u6b21read()\u8fd4\u56de-1\uff0c\u51fa\u9519\u7801\u4e3aEAGAIN(EAGAIN\u7b49\u4e8eEWOULDBLOCK)\uff0c\u4e8e\u662f\u4ee3\u7801\u77e5\u9053\u5df2\u7ecf\u63a5\u6536\u5b8c\u6570\u636e\u3002\u4e00\u5171\u53ea\u4f7f\u7528\u4e861026\u6b21\u7cfb\u7edf\u8c03\u7528\u5c31\u8bfb\u5b8c\u4e86\u6570\u636e\u3002 \u603b\u7ed3\uff1a\u5373\u4f7f\u4f7f\u7528\u7535\u5e73\u89e6\u53d1\u4e5f\u4e0d\u8981\u4f9d\u8d56epoll_wait()\u901a\u77e5\u8c03\u7528\u8005\u5230\u8fbe\u4e8b\u4ef6\uff0c\u9700\u8981\u5faa\u73af\u8c03\u7528IO\u51fd\u6570\u76f4\u5230\u88ab\u901a\u77e5EAGAIN\uff0c\u8fd9\u6837\u5c31\u628aepoll_wait()\u7684\u8c03\u7528\u6b21\u6570\u964d\u5230\u6700\u4f4e\uff0c\u4ec5\u7ba1\u6709\u53ef\u80fd\u5728\u4e0b\u6b21epoll_wait()\u65f6\u4f1a\u6709\u53ef\u80fd\u6d6a\u8d39\u4e00\u6b21\u6587\u4ef6\u7684poll()\u8c03\u7528\uff0c\u4f46\u8fd9\u4e2a\u5f88\u5c0f\u7684\u5f00\u9500\u53ef\u4ee5\u5ffd\u7565\u3002 &nbsp; \u4e8c.&nbsp;\u4e3a\u4ec0\u4e48epoll\u652f\u6301\u5d4c\u5957\u8c03\u7528 \u8bfbepoll\u7684\u5b9e\u73b0\u4ee3\u7801\u53d1\u73b0\uff0c\u4e00\u4e2aepoll\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26epfd\u53ef\u4ee5\u5d4c\u5957\u7684\u52a0\u5165\u53e6\u4e00\u4e2aepoll\u3002\u8fd9\u6837\u6709\u4ec0\u4e48\u7528\u5462\uff1f epoll\u7684\u5b9e\u73b0\u4e2d&ldquo;\u5e73\u7b49\u7684&rdquo;\u5bf9\u5f85\u6bcf\u4e2a\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\uff0c\u5b83\u4eec\u7ef4\u62a4\u5728\u4e00\u68f5\u7ea2\u9ed1\u6811\u4e4b\u4e2d\uff0c\u5047\u5982\u6709\u5341\u4e07\u4e2a\u6587\u4ef6\u88ab\u76d1\u89c6\uff0c\u90a3\u4e48\u67e5\u627e\u67d0\u4e2a\u6587\u4ef6\u65f6\u5c31\u8981\u5728\u8fd9\u5341\u4e07\u4e2a\u6587\u4ef6\u4e2d\u67e5\u627e\u3002\u5373\u4f7f\u7ea2\u9ed1\u6811\u7684\u67e5\u627e\u6548\u7387\u662flog(n)\uff0c\u6587\u4ef6\u975e\u5e38\u5927\u65f6\u4e5f\u662f\u6bd4\u8f83\u6d88\u8017\u65f6\u95f4\u7684\u3002 \u90a3\u4e48\u5047\u5982\u6709\u8fd9\u6837\u4e00\u79cd\u60c5\u51b5\uff0c\u5982\u679c\u8fd9\u5341\u4e07\u4e2a\u6587\u4ef6\u4e2d\u53ea\u67091000\u4e2a\u662f\u6d3b\u8dc3\u7684\uff0c\u6216\u8005\u8bf4\u8fd91000\u4e2a\u6587\u4ef6\u4f18\u5148\u7ea7\u6700\u9ad8\u3002\u90a3\u4e48\u5219\u6709\u4e00\u79cd\u4f18\u5316\u65b9\u6848\u662f\uff0c\u521b\u5efa\u4e24\u4e2aepoll\uff0c\u7b2c\u4e00\u4e2aepoll\uff08epfd0\uff09\u76d1\u63a7100000&nbsp;&#8211;&nbsp;1000&nbsp;\u4e2a\u6587\u4ef6\uff0c\u7b2c\u4e8c\u4e2aepoll&nbsp;(epfd1)&nbsp;\u76d1\u63a71000\u4e2a\u9ad8\u4f18\u5148\u7ea7\u6587\u4ef6\u4ee5\u53caepfd0\u3002\u8fd9\u6837\u7684\u597d\u5904\u662f\uff0c\u5927\u591a\u6570\u60c5\u51b5\u4e0bepoll\u5b9e\u73b0\u53ea\u57281001\u4e2a\u5143\u7d20\u7684\u7ea2\u9ed1\u6811\u4e2d\u67e5\u627e\uff0c\u81ea\u7136\u6548\u7387\u63d0\u9ad8\u4e86\u3002 \u603b\u7ed3\uff1aepoll\u7684\u5d4c\u5957\u8c03\u7528\u7ed9\u5f00\u53d1\u8005\u63d0\u4f9b\u4e86\u4e00\u4e2a\u5728\u9ad8\u5e76\u53d1\u73af\u5883\u4e0b\u7684\u4f18\u5316\u65b9\u6848\u3002 &nbsp; \u4e09.&nbsp;epoll\u7684\u6548\u7387\u4e00\u5b9a\u6bd4select\/poll\u9ad8\u5417\u3002 &nbsp;&nbsp;&nbsp;&nbsp;\u7b54\u6848\u662f\u4e0d\u4e00\u5b9a\u3002 Select\u7684\u7f3a\u70b9\u5927\u81f4\u6709\uff1a 1.&nbsp;\u5185\u6838\u4e2d\u5199\u6b7b\u4e86\u6700\u591a\u53ea\u80fd\u76d1\u89c61024\u4e2a\u6587\u4ef6. 2.&nbsp;\u6bcf\u6b21\u8c03\u7528select\u90fd\u8981\u628a\u5173\u5fc3\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u548c\u5173\u5fc3\u7684\u6587\u4ef6\u4ef6\u4ece\u4e00\u4e2a\u7528\u6237\u7a7a\u95f4\u7684\u957f\u957f\u7684\u6570\u7ec4\u62f7\u8d1d\u5230\u5185\u6838\u7a7a\u95f4. 3.&nbsp;select\u82e5\u4f7f\u5f97caller\u8fdb\u7a0b\u8fdb\u5165\u7761\u7720\u540e\uff0c\u67d0\u4e2a\u6587\u4ef6\u6709\u4e8b\u4ef6\u5230\u8fbe\u6b64\u8fdb\u7a0b\u88ab\u5524\u9192\uff0c\u90a3\u4e48\u6240\u6709\u88ab\u76d1\u89c6\u7684\u6587\u4ef6\u5168\u90e8\u4f1a\u88ab\u8c03\u7528poll()\u8be2\u95ee&ldquo;\u4f60\u6709\u6ca1\u6709\u4e8b\u4ef6\u5230\u8fbe&rdquo;\uff0c\u8fd9\u662f\u4e00\u4e2a\u7ebf\u6027\u7684\u65f6\u95f4\u590d\u6742\u5ea6\u3002 epoll\u9488\u5bf9select\u7684\u4e09\u4e2a\u7f3a\u70b9\u7684\u6539\u8fdb\uff1a 1.&nbsp;\u76d1\u89c6\u7684\u6587\u4ef6\u6570\u7531\u53d6\u51b3\u4e8e\u7cfb\u7edf\u4e2d\u6709\u591a\u5c11\u4f4e\u7aef\u5185\u5b58(x86_64\u67b6\u6784\u4e2d\u7684\u6240\u6709\u5185\u5b58\u90fd\u662f\u4f4e\u7aef\u5185\u5b58)\u30023.9.6\u7248\u672c\u7684\u5185\u6838\u5b9e\u73b0\u4e2d\uff0c\u5bf9\u4e8e\u6bcf\u4e2a\u767b\u5f55\u7528\u6237\uff0c\u6700\u591a\u4f7f\u7528\u7cfb\u7edf\u4e2d\u4f4e\u7aef\u5185\u5b58\u76844%\u7528\u6765\u521b\u5efa\u76d1\u89c6\u7528\u7684\u6570\u636e\u7ed3\u6784\u3002\u89c1\u7b2c1951\u884c\u4ee3\u7801\u3002max_user_watches&nbsp;=&nbsp;(((si.totalram&nbsp;&#8211;&nbsp;si.totalhigh)&nbsp;\/&nbsp;25)&nbsp;&lt;&lt;&nbsp;PAGE_SHIFT)&nbsp;\/&nbsp;EP_ITEM_COST; 2.&nbsp;\u7528\u6237\u53ea\u9700\u8981\u628a\u5173\u5fc3\u7684\u6587\u4ef6\u5bf9\u5e94\u7684\u6570\u636e\u7ed3\u6784\u5728\u8c03\u7528epoll_wait()\u524d\u7528epoll_ctl()\u4e00\u6b21\u6027\u4f20\u5165\u5185\u5b58\uff0c\u4ee5\u540e\u8c03\u7528epoll_wait()\u65f6\u4e0d\u9700\u8981\u50cfselect\u4e00\u6837\u62f7\u8d1d\u5927\u91cf\u6570\u636e\u3002 3.&nbsp;\u5f53\u8c03\u7528epoll_wait()\u7684caller\u8fdb\u7a0b\u7761\u7720\u65f6\uff0c\u7a81\u7136\u6709\u4e8b\u4ef6\u5230\u8fbe\uff0ccaller\u8fdb\u7a0b\u88ab\u5524\u9192\uff0cepoll_wait()\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\uff0c\u5185\u6838\u5e76\u4e0d\u904d\u5386\u6ca1\u6709\u76d1\u89c6\u7684\u6587\u4ef6\uff0c\u800c\u53ea\u62a5\u544a\u5728\u4e00\u4e2a\u5373\u77ed\u65f6\u95f4\u5185\u53d1\u751f\u7684\u4e8b\u4ef6\u3002\u4e0b\u9762\u66f4\u8be6\u7ec6\u7684\u63cf\u8ff0\u8fd9\u4e2a\u573a\u666f\uff0c\u4ee5\u76d1\u89c6tcp&nbsp;socket\u4e3e\u4f8b\uff0c\u5927\u81f4\u662f\uff1a\u67d0\u8fdb\u7a0b\u8c03\u7528epoll_wait()\uff0c\u6b64\u65f6\u6ca1\u6709\u4efb\u4f55\u5b83\u5173\u5fc3\u7684\u4e8b\u4ef6\u53d1\u751f\uff0c\u4e8e\u662fcaller\u8fdb\u7a0b\u8fdb\u5165\u7761\u7720\u3002\u5904\u7406\u5668\u8c03\u5ea6\u4e86\u5176\u5b83\u8fdb\u7a0b\u3002\u6570\u636e\u5230\u8fbe\u65f6\uff0c\u5f53\u524d\u8fdb\u7a0b\u88ab\u786c\u4ef6\u4e2d\u65ad\uff0c\u7f51\u5361\u9a71\u52a8\u6536\u5230\u6570\u636e\u5305\uff0c\u6570\u636e\u5305\u5728\u4e2d\u65ad\u5904\u7406\u51fd\u6570\u4e2d\u88ab\u62f7\u5165\u5185\u6838\uff0c\u4e2d\u65ad\u5904\u7406\u51fd\u6570\u8bbe\u7f6e\u4e2d\u65ad\u4e0b\u534a\u90e8(Half&nbsp;Bottom)\u3002\u4e0b\u534a\u90e8\u88ab\u5904\u7406\u5668\u8c03\u5ea6\uff0c\u8c03\u7528epoll\u5b9e\u73b0\u4ee3\u7801\u6ce8\u518c\u7684\u56de\u8c03\u51fd\u6570ep_poll_callback()\u3002ep_poll_callback()\u51fd\u6570\u5524\u9192\u4e4b\u524d\u7684caller\u8fdb\u7a0b\uff0ccaller\u8fdb\u7a0b\u91cd\u65b0\u83b7\u5f97CPU\uff0c\u4eceepoll\u5b9e\u73b0\u7684ep_poll()\u51fd\u6570\u4e2d\u6062\u590d\u6267\u884c\uff0c\u57283.9.6\u5185\u6838\u4e2d\u7684\u7b2c1564\u884c\uff1a&nbsp;if&nbsp;(!schedule_hrtimeout_range(to,&nbsp;slack,&nbsp;HRTIMER_MODE_ABS))\u3002\u7136\u540e\uff0c\u5185\u6838\u4ee3\u7801\u5f00\u59cb\u6536\u96c6\u5df2\u7ecf\u5c31\u7eea\u7684\u6587\u4ef6\u548c\u53d1\u751f\u7684\u4e8b\u4ef6\uff0c\u53d1\u56de\u7528\u6237\u7a7a\u95f4\u3002\u53ea\u6709\u4ece\u7b2c\u4e00\u6b21\u56de\u8c03\u51fd\u6570ep_poll_callback()\u88ab\u9a71\u52a8\u7684\u4ee3\u7801\u8c03\u7528\uff08caller\u8fdb\u7a0b\u8fd8\u5728\u7761\u7720\u65f6\u6267\u884c\u7684ep_poll_callback()\u7b97\u7b2c\u4e00\u6b21\uff09\u5230epoll\u5b9e\u73b0\u4ee3\u7801\u8d70\u5230\u7b2c586\u884c\u5173\u95ed\u4e2d\u65ad\u5173\u95ed\u4e2d\u65ad\u7684\u4ee3\u7801&nbsp;spin_lock_irqsave(&amp;ep-&gt;lock,&nbsp;flags);\u4e4b\u95f4\u53d1\u751f\u7684\u4e8b\u4ef6\u624d\u4f1a\u88ab\u6536\u96c6\u3002 &nbsp;&nbsp;&nbsp;&nbsp;\u5bf9\u4e8e\u7b2c3\u70b9\uff0c\u8fd9\u662fepoll\u7684\u4f18\u70b9\uff0c\u4f46\u5728\u67d0\u79cd\u60c5\u51b5\u4e0b\u5374\u4f1a\u662fepoll\u7684\u7f3a\u70b9\u3002\u7f51\u4e0a\u5f88\u591a\u6bd4\u8f83poll,&nbsp;select,&nbsp;epoll\u6027\u80fd\u7684\u6587\u7ae0\uff0c\u6ca1\u6765\u5f97\u53ca\u4ed4\u7ec6\u770b\uff0c\u6211\u4e2a\u4eba\u8ba4\u4e3a\u7ed3\u8bba\u662f\u53ef\u9760\u7684\u3002\u7ed3\u8bba\u5f15\u5165\u4e86\u4e00\u4e2a\u6982\u5ff5active-to-total&nbsp;ratio\uff0c\u8bbe\u6240\u6709\u88ab\u76d1\u63a7\u7684\u6587\u4ef6\u6570\u662fn\uff0c\u6d3b\u8dc3\u7684\u6587\u4ef6\u6570\u662fm\uff0cactive-to-total\u6bd4\u5219\u662fm\/n\uff0c\u5982\u679c\u8fd9\u4e2a\u6bd4\u975e\u5e38\u9ad8\uff0c\u6bd4\u5982\u5927\u4e8e0.7\uff0c\u5219poll\u6216select\u7684\u6027\u80fd\u8981\u9ad8\u8fc7epoll\uff0c\u53cd\u4e4b\u5219epoll\u80dc\u51fa\u3002 &nbsp;&nbsp;&nbsp;&nbsp;\u5bf9\u6bd4\u524d\u6587\u5bf9select\u7684\u7b2c3\u4e2a\u7f3a\u70b9\u548cepoll\u7684\u6539\u8fdb\u70b93\u7684\u53d9\u8ff0\u53ef\u4ee5\u89e3\u91ca\u8fd9\u4e2a\u539f\u56e0\u3002\u56e0\u4e3aselect\u5728\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u524d\u53c8\u8f6e\u5faa\u4e86\u6240\u6709\u5173\u5fc3\u7684\u6587\u4ef6\uff0c\u800c\u8fd9\u4e9b\u6587\u4ef6\u53c8\u5927\u90e8\u5206\u662f\u6709\u4e8b\u4ef6\u53d1\u751f\u7684\uff0c\u6240\u4ee5select\u6240\u505a\u7684\u5de5\u4f5c\u5e76\u6ca1\u6709\u6d6a\u8d39\uff0c\u4f46epoll\u53ea\u6536\u96c6\u4e86\u4e00\u5c0f\u6bb5\u65f6\u95f4\u4e2d\u53d1\u751f\u7684\u4e8b\u4ef6\uff0c\u4e8e\u662fselect\u8f83\u4e4bepoll\u51cf\u5c11\u4e86\u7528\u6237\u7a7a\u95f4\u548c\u5185\u6838\u7a7a\u95f4\u7684\u9891\u7e41\u5207\u6362\uff0c\u4ece\u800c\u8ba9select\u7684\u6027\u80fd\u53cd\u8d85epoll\u3002 \u90a3\u4e48\u5982\u4f55\u6539\u8fdb\u5462\uff1f\u660e\u767d\u4e86\u4ee5\u4e0a\u7684\u539f\u56e0\uff0c\u90a3\u4e48\u5c31\u53ef\u4ee5\u5bf9epoll\u505a\u51fa\u6539\u8fdb\uff0c\u7406\u8bba\u4e0a\u5bf9\u4e8eactive-to-total\u6bd4\u8f83\u9ad8\u7684\u5e94\u7528\u73af\u5883\u4e0b\uff0c\u53ef\u4ee5\u5728epoll\u7684\u5b9e\u73b0\u4e2d\u52a0\u5165\u4e0eselect\u505a\u6cd5\u76f8\u540c\u903b\u8f91\uff0c\u5373\u9000\u51fa\u524d\u8be2\u95ee\u6240\u6709\u7684\u76d1\u63a7\u6587\u4ef6\uff0c\u53cd\u6b63active-to-total\u6bd4\u5f88\u9ad8\u3002\u6216\u8005\u66f4\u597d\u7684\u65b9\u6848\uff0c\u7528\u4e00\u4e2a\u94fe\u8868\u94fe\u63a5\u6d3b\u8dc3\u7684\u6587\u4ef6\uff0c\u5728epoll\u8fd4\u56de\u7528\u6237\u7a7a\u95f4\u524d\u904d\u5386\u8fd9\u4e2a\u94fe\u8868\uff0c\u4e89\u53d6\u6bcf\u4e00\u4e2aepoll_wait()\u8c03\u7528\u8fd4\u56de\u5c3d\u53ef\u80fd\u591a\u7684\u4e8b\u4ef6\u3002 &nbsp; \u9644\uff1aepoll\u7684\u4e3b\u8981\u6570\u636e\u7ed3\u6784\u7b80\u4ecb. epoll\u63a5\u53e3\u7684\u4e3b\u8981\u6570\u636e\u7ed3\u6784\u6709struct&nbsp;eventpoll\uff0cstruct&nbsp;epitem\uff0cstruct&nbsp;eppoll_entry\u3002 &nbsp;&nbsp;&nbsp;&nbsp;\u5728\u8bb2\u8ff0\u8fd9\u4e09\u4e2a\u6570\u636e\u7ed3\u6784\u524d\u5148\u63d0\u4e00\u4e0bstruct&nbsp;file\u3002Unix\u8bbe\u8ba1\u521d\u671f\u5e0c\u671b\u5b83\u7684\u8bbe\u8ba1\u9075\u4ece&ldquo;\u4e00\u5207\u7686\u6587\u4ef6&rdquo;\u7684\u7406\u5ff5\u3002\u5728Linux\u5185\u6838\u4e2d\uff0c\u6bcf\u4e2a\u62bd\u8c61\u7684\u6587\u4ef6\u5bf9\u5e94\u4e00\u4e2a\u5185\u6838struct&nbsp;file\u7ed3\u6784\u4f53\u3002Struct&nbsp;file\u7ed3\u6784\u4f53\u4e2d\u6709\u4e00\u4e2avoid&nbsp;*private_data\u57df\u3002\u4e0d\u540c\u7684\u6587\u4ef6\u7c7b\u578b\u4f1a\u5728private_data\u57df\u4e2d\u5b58\u653e\u7279\u5b9a\u7684\u4fe1\u606f\u3002Struct&nbsp;file\u4e2d\u53e6\u4e00\u4e2a\u57dff_op\u662f\u51fd\u6570\u6307\u9488\u7684\u5217\u8868\uff0c\u5b83\u8bb0\u5f55\u4e86\u5bf9\u5e94\u8be5\u6587\u4ef6\u7684\u64cd\u4f5c\u3002\u6240\u6709epoll\u6587\u4ef6\u7684f_op\u90fd\u6307\u5411static&nbsp;const&nbsp;struct&nbsp;file_operations&nbsp;eventpoll_fops\uff0c\u56e0\u6b64\u53ef\u4ee5\u4ee3\u7801\u5224\u65ad\u4e00\u4e2a\u6587\u4ef6\u662f\u4e0d\u662fepoll\u5982\u4e0b\uff1a static&nbsp;inline&nbsp;int&nbsp;is_file_epoll(struct&nbsp;file&nbsp;*f) { &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;f-&gt;f_op&nbsp;==&nbsp;&amp;eventpoll_fops; } &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;\u6bcf\u6b21\u6210\u529f\u8c03\u7528epoll_create\u65f6\u5c31\u4f1a\u521b\u5efa\u4e00\u4e2astruct&nbsp;file\u7684\u7ed3\u6784\u4f53\uff0c\u548c\u4e00\u4e2astruct&nbsp;eventpoll\u3002Struct&nbsp;file\u4e2d\u7684private_data\u6307\u5411struct&nbsp;eventpoll\u3002eventpoll\u7ef4\u62a4\u4e86\u8fd9\u4e2aepoll\u7684\u91cd\u8981\u4fe1\u606f\u3002\u5176\u4e2d\u6bd4\u8f83\u91cd\u8981\u7684\u51e0\u4e2a\u5b57\u6bb5\u6709\uff1a\u4e00\u4e2a\u5faa\u73af\u5217\u8868struct&nbsp;list_head&nbsp;&nbsp;rdllist\u94fe\u63a5\u4e86\u8be5epll\u4e2d\u5df2\u7ecf\u53ef\u4ee5\u8bfb\u5199\u6216\u8005\u6709\u51fa\u9519\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002\u4e00\u4e2a\u7ea2\u9ed1\u6811\u7684\u6839\u7ed3\u70b9struct&nbsp;rb_root&nbsp;&nbsp;rbr\uff0ceventpoll\u7ef4\u62a4\u4e86\u4e00\u68f5\u7ea2\u9ed1\u6811\uff0c\u6811\u4e2d\u7684\u7ed3\u70b9\u662fstruct&nbsp;epitem\u3002 \u6bcf\u4e2a\u88ab\u52a0\u5165\u5230epoll\u4e2d\u88ab\u5173\u6ce8\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u90fd\u5bf9\u5e94\u4e00\u4e2astruct&nbsp;epitem\u7ed3\u6784\u4f53\u3002\u6240\u6709\u52a0\u5165\u5230\u540c\u4e00\u4e2aepoll\u4e2d\u5bf9\u5e94\u7684\u6240\u6709epitem\u90fd\u6302\u5728\u7ea2\u9ed1\u6811\u4e0a\u3002\u8be5\u7ea2\u9ed1\u6811\u7684\u6839\u7ed3\u6784\u4fdd\u5b58\u5728struct&nbsp;eventpoll\u4e2d\u3002epitem\u4e2d\u8bb0\u5f55\u4e86\u5bf9\u5e94\u7684\u6587\u4ef6\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u548c\u6587\u4ef6\u6307\u9488\u3002 struct&nbsp;eppoll_entry\u662f\u7528\u6765\u6302\u63a5\u5230\u8bbe\u5907\u6587\u4ef6\u4e2d\u7684\u7ed3\u6784\u4f53\u3002\u8bbe\u5907\u9a71\u52a8\u5728\u5f97\u77e5\u81ea\u5df1\u53ef\u8bfb\u6216\u53ef\u5199\u6216\u6709\u9519\u8bef\u65f6\u901a\u8fc7\u8fd9\u4e2a\u7ed3\u6784\u4f53\u901a\u77e5\u6709\u4e8b\u4ef6\u53d1\u751f\u3002\u6bcf\u4e2aeppoll_entry\u90fd\u6307\u5411\u4e00\u4e2aepitem\uff0c\u4e00\u4e2aepitem\u53ef\u80fd\u5bf9\u5e94\u591a\u4e2aeppoll_entry\u3002eppoll_entry\u4e2d\u7684\u57dfwait_queue_t&nbsp;&nbsp;wait\u5c31\u662f\u88ab\u7528\u6765\u6302\u63a5\u5230\u8bbe\u5907\u6587\u4ef6\u4e2d\u7684\u7b49\u5f85\u961f\u5217\u3002\u8bbe\u5907\u6587\u4ef6\u901a\u8fc7wait\u53ef\u4ee5\u62ff\u5230eppoll_entry\uff0c\u518d\u901a\u8fc7eppoll_entry\u62ff\u5230epitem\uff0c\u518d\u62ff\u5230eventpoll\u3002 &nbsp; &nbsp;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,6,7],"tags":[51],"class_list":["post-976","post","type-post","status-publish","format-standard","hentry","category-network","category-tech_articles","category-unix_linux","tag-linux-2"],"_links":{"self":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts\/976","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=976"}],"version-history":[{"count":0,"href":"https:\/\/ykyi.net\/index.php?rest_route=\/wp\/v2\/posts\/976\/revisions"}],"wp:attachment":[{"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=976"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=976"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ykyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=976"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}