{"id":19,"date":"2025-10-07T22:39:27","date_gmt":"2025-10-07T14:39:27","guid":{"rendered":"http:\/\/47.99.178.170\/?p=19"},"modified":"2025-10-23T21:45:19","modified_gmt":"2025-10-23T13:45:19","slug":"19","status":"publish","type":"post","link":"https:\/\/www.garfield-blog.top\/?p=19","title":{"rendered":"\u3010\u6e90\u7801\u89e3\u6790\u3011\u3010Linux\u3011epoll\u539f\u7406"},"content":{"rendered":"\n
\n

\u53c2\u8003\u6587\u6863\uff1a<\/p>\n\n\n\n

\u3010Linux\u6df1\u5165\u3011epoll\u6e90\u7801\u5256\u6790_epoll\u5256\u6790-CSDN\u535a\u5ba2<\/a><\/p>\n\n\n\n

epoll\u6e90\u7801\u6df1\u5ea6\u5256\u6790 – \u575a\u6301\uff0c\u6bcf\u5929\u8fdb\u6b65\u4e00\u70b9\u70b9 – \u535a\u5ba2\u56ed (cnblogs.com)<\/a><\/p>\n\n\n\n

\u56fe\u89e3 | \u6df1\u5165\u63ed\u79d8 epoll \u662f\u5982\u4f55\u5b9e\u73b0 IO \u591a\u8def\u590d\u7528\u7684\uff01-\u817e\u8baf\u4e91\u5f00\u53d1\u8005\u793e\u533a-\u817e\u8baf\u4e91 (tencent.com)<\/a><\/p>\n\n\n\n

Linux eventpoll\u89e3\u6790 – aspirs – \u535a\u5ba2\u56ed (cnblogs.com)<\/a><\/p>\n\n\n\n

\u4ecelinux\u6e90\u7801\u770bepoll – \u65e0\u6bc1\u7684\u6e56\u5149-Al\u7684\u4e2a\u4eba\u7a7a\u95f4 – OSCHINA – \u4e2d\u6587\u5f00\u6e90\u6280\u672f\u4ea4\u6d41\u793e\u533a<\/a><\/p>\n\n\n\n

Linux 5.4\u6e90\u7801<\/a><\/p>\n<\/blockquote>\n\n\n\n

\u4e00\u3001 \u53d1\u5c55\u5386\u53f2<\/h2>\n\n\n\n

API \u53d1\u5e03\u7684\u65f6\u95f4\u7ebf<\/strong><\/h3>\n\n\n\n

\u4e0b\u6587\u4e2d\u5217\u51fa\u4e86\u7f51\u7edc IO \u4e2d\uff0c\u5404\u4e2a api \u7684\u53d1\u5e03\u65f6\u95f4\u7ebf<\/p>\n\n\n\n

\n

1983\uff0csocket \u53d1\u5e03\u5728 Unix(4.2 BSD) 1983\uff0cselect \u53d1\u5e03\u5728 Unix(4.2 BSD) 1994\uff0cLinux\u76841.0\uff0c\u5df2\u7ecf\u652f\u6301socket\u548cselect 1997\uff0cpoll \u53d1\u5e03\u5728 Linux 2.1.23 2002\uff0cepoll\u53d1\u5e03\u5728 Linux 2.5.44<\/p>\n<\/blockquote>\n\n\n\n

\u53ef\u4ee5\u770b\u5230select<\/code>\u3001poll<\/code> \u548c epoll<\/code>\uff0c\u8fd9\u4e09\u4e2a\u201cIO<\/code>\u591a\u8def\u590d\u7528API<\/code>\u201d\u662f\u76f8\u7ee7\u53d1\u5e03\u7684\u3002\u8fd9\u8bf4\u660e\u4e86\uff0c\u5b83\u4eec\u662fIO<\/code>\u591a\u8def\u590d\u7528\u76843\u4e2a\u8fdb\u5316\u7248\u672c\u3002\u56e0\u4e3aAPI<\/code>\u8bbe\u8ba1\u7f3a\u9677\uff0c\u65e0\u6cd5\u5728\u4e0d\u6539\u53d8 API<\/code> \u7684\u524d\u63d0\u4e0b\u4f18\u5316\u5185\u90e8\u903b\u8f91\u3002\u6240\u4ee5\u7528poll<\/code>\u66ff\u4ee3select<\/code>\uff0c\u518d\u7528epoll<\/code>\u66ff\u4ee3poll<\/code><\/p>\n\n\n\n

epoll<\/code>\u548cpoll<\/code>\u8fd8\u6709select<\/code>\u90fd\u662f\u76d1\u542csocket<\/code>\u7684\u63a5\u53e3\uff0cpoll<\/code>\u8fd8\u6709select<\/code>\u51fa\u73b0\u7684\u65f6\u95f4\u66f4\u65e9\uff0c\u4f46\u662f\u6027\u80fd\u66f4\u5dee\u3002\u540e\u6765\u5728\u6b64\u7ee7\u627f\u4e0a\u53d1\u5c55\u6539\u8fdb\u5f97\u5230\u4e86epoll<\/code><\/p>\n\n\n\n

\u4e8c\u3001epoll\u662f\u4ec0\u4e48<\/h2>\n\n\n\n

epoll<\/code>\u662f\u4e00\u79cdI\/O<\/code>\u4e8b\u4ef6\u901a\u77e5\u673a\u5236\uff0c\u662flinux<\/code>\u5185\u6838\u5b9e\u73b0IO<\/code>\u591a\u8def\u590d\u7528\u7684\u4e00\u4e2a\u5b9e\u73b0\u3002 IO<\/code>\u591a\u8def\u590d\u7528\u662f\u6307\uff0c\u5728\u4e00\u4e2a\u64cd\u4f5c\u91cc\u540c\u65f6\u76d1\u542c\u591a\u4e2a\u8f93\u5165\u8f93\u51fa\u6e90\uff0c\u5728\u5176\u4e2d\u4e00\u4e2a\u6216\u591a\u4e2a\u8f93\u5165\u8f93\u51fa\u6e90\u53ef\u7528\u7684\u65f6\u5019\u8fd4\u56de\uff0c\u7136\u540e\u5bf9\u5176\u7684\u8fdb\u884c\u8bfb\u5199\u64cd\u4f5c\u3002<\/p>\n\n\n\n

epoll<\/code>\u7684\u901a\u4fd7\u89e3\u91ca\u662f\u4e00\u79cd\u5f53\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u5185\u6838\u7f13\u51b2\u533a\u975e\u7a7a\u7684\u65f6\u5019\uff0c\u53d1\u51fa\u53ef\u8bfb\u4fe1\u53f7\u8fdb\u884c\u901a\u77e5\uff0c\u5f53\u5199\u7f13\u51b2\u533a\u4e0d\u6ee1\u7684\u65f6\u5019\uff0c\u53d1\u51fa\u53ef\u5199\u4fe1\u53f7\u901a\u77e5\u7684\u673a\u5236<\/p>\n\n\n\n

\u4e09\u3001epoll\u63a5\u53e3\u793a\u4f8b\u4ee3\u7801<\/h2>\n\n\n\n

\u521b\u5efa\u4e00\u4e2aepoll<\/code>\u8fde\u63a5\uff0c\u76d1\u542c\u6807\u51c6\u8f93\u5165\u3002\u6253\u5370\u7528\u6237\u8f93\u5165\u7684\u503c\uff0c\u82e5\u8f93\u5165exit<\/code>\u5219\u76f4\u63a5\u9000\u51fa\u7ed3\u675f\u8fdb\u7a0b<\/p>\n\n\n\n

#include <stdio.h>\n#include <stdlib.h>\n#include <unistd.h>\n#include <sys\/epoll.h>\n\u200b\n#define MAX_EVENTS 10\n\u200b\nint main() {\n    int epoll_fd, nfds, n;\n    struct epoll_event event;\n    struct epoll_event events[MAX_EVENTS];\n    char buf[256];\n\u200b\n    \/\/ \u521b\u5efa\u4e00\u4e2aepoll\u5b9e\u4f8b\n    epoll_fd = epoll_create1(0);\n    if (epoll_fd == -1) {\n        perror(\"epoll_create1\");\n        exit(EXIT_FAILURE);\n    }\n\u200b\n    \/\/ \u6dfb\u52a0\u6807\u51c6\u8f93\u5165\u6587\u4ef6\u63cf\u8ff0\u7b26\u5230epoll\u5b9e\u4f8b\u4e2d\n    event.events = EPOLLIN;\n    event.data.fd = STDIN_FILENO;\n    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, STDIN_FILENO, &event) == -1) {\n        perror(\"epoll_ctl\");\n        exit(EXIT_FAILURE);\n    }\n\u200b\n    while (1) {\n        \/\/ \u7b49\u5f85\u4e8b\u4ef6\u53d1\u751f\n        nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);\n        if (nfds == -1) {\n            perror(\"epoll_wait\");\n            exit(EXIT_FAILURE);\n        }\n\u200b\n        \/\/ \u5904\u7406\u5c31\u7eea\u7684\u4e8b\u4ef6\n        for (n = 0; n < nfds; ++n) {\n            if (events[n].data.fd == STDIN_FILENO) {\n                \/\/ \u4ece\u6807\u51c6\u8f93\u5165\u4e2d\u8bfb\u53d6\u6570\u636e\n                if (fgets(buf, sizeof(buf), stdin) == NULL) {\n                    perror(\"fgets\");\n                    exit(EXIT_FAILURE);\n                }\n                printf(\"Received input: %s\", buf);\n                \/\/ \u5982\u679c\u6536\u5230exit\uff0c\u5219\u9000\u51fa\u5faa\u73af\n                if (strcmp(buf, \"exit\\n\") == 0) {\n                    goto cleanup;\n                }\n            }\n        }\n    }\n\u200b\ncleanup:\n    close(epoll_fd);\n    return 0;\n}<\/code><\/pre>\n\n\n\n
\u56db\u3001\u6838\u5fc3\u6570\u636e\u7ed3\u6784<\/h2>\n\n\n\n
4.1 epoll<\/code>\u6838\u5fc3\u7ed3\u6784\u4f53<\/h3>\n\n\n\n
1) struct eventpoll<\/code><\/h4>\n\n\n\n
\u8fd9\u4e2a\u6570\u636e\u7ed3\u6784\u662f\u6211\u4eec\u5728\u8c03\u7528epoll_create<\/code>\u4e4b\u540e\u5185\u6838\u4fa7\u521b\u5efa\u7684\u4e00\u4e2a\u53e5\u67c4\uff0c\u8868\u793a\u4e86\u4e00\u4e2aepoll<\/code>\u5b9e\u4f8b\u3002\u540e\u7eed\u5982\u679c\u6211\u4eec\u518d\u8c03\u7528epoll_ctl<\/code>\u548cepoll_wait<\/code>\u7b49\uff0c\u90fd\u662f\u5bf9\u8fd9\u4e2aeventpoll<\/code>\u6570\u636e\u8fdb\u884c\u64cd\u4f5c\uff0c\u8fd9\u90e8\u5206\u6570\u636e\u4f1a\u88ab\u4fdd\u5b58\u5728do_epoll_create<\/code>\u521b\u5efa\u7684\u533f\u540d\u6587\u4ef6file<\/code>\u7684private_data<\/code>\u5b57\u6bb5\u4e2d<\/p>\n\n\n\n
struct eventpoll {
    \/* \u4e92\u65a5\u9501 *\/
    struct mutex mtx;
\u200b
    \/* \u7b49\u5f85\u961f\u5217\uff0c\u6267\u884cepoll_Wait\u52a0\u5165\u7b49\u5f85\u961f\u5217*\/
    wait_queue_head_t wq;
\u200b
    \/* 
     * \u7b49\u5f85\u961f\u5217\u7684file->poll()
     * \u8fd9\u4e2a\u961f\u5217\u91cc\u5b58\u653e\u7684\u662f\u8be5eventloop\u4f5c\u4e3apoll\u5bf9\u8c61\u7684\u4e00\u4e2a\u5b9e\u4f8b\uff0c\u52a0\u5165\u5230\u7b49\u5f85\u7684\u961f\u5217
     * \u8fd9\u662f\u56e0\u4e3aeventpoll\u672c\u8eab\u4e5f\u662f\u4e00\u4e2afile, \u6240\u4ee5\u4e5f\u4f1a\u6709poll\u64cd\u4f5c
     *\/
    wait_queue_head_t poll_wait;
\u200b
    \/* \u5c31\u7eea\u94fe\u8868 *\/
    struct list_head rdllist;
\u200b
    \/* \u7528\u4e8erdllist\u548covflist\u7684\u8bfb\u5199\u9501 *\/
    rwlock_t lock;
\u200b
    \/* \u6307\u5411\u88ab\u68c0\u89c6\u5bf9\u8c61\u5b58\u50a8\u7684\u7ea2\u9ed1\u6811 *\/
    struct rb_root_cached rbr;
\u200b
    \/*
     * This is a single linked list that chains all the \"struct epitem\" that
     * happened while transferring ready events to userspace w\/out
     * holding ->lock.
     *\/
    struct epitem *ovflist;
    struct wakeup_source *ws;
\u200b
    \/* \u521b\u5efaeventpoll\u63cf\u8ff0\u7b26\u7684\u7528\u6237 *\/
    struct user_struct *user;
    
    \/* eventloop\u5bf9\u5e94\u7684\u533f\u540d\u6587\u4ef6 *\/
    struct file *file;
\u200b
    \/* \u7528\u4e8e\u68c0\u6d4b\u662f\u5426\u6709\u5d4c\u5957\u8c03\u7528\u9020\u6210\u73af\u8def *\/
    int visited;
    struct list_head visited_list_link;
\u200b
    \/* \u7528\u4e8e\u8ffd\u8e2a\u5fd9poll\u7684napi_id *\/
    unsigned int napi_id;
};<\/code><\/pre>\n\n\n\n
\u521b\u5efaeventpoll<\/code>\u8282\u70b9<\/p>\n\n\n\n
ep_alloc<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
\u5206\u914deventpoll<\/code>\u8282\u70b9\u5185\u5b58\uff0c\u521d\u59cb\u5316epoll<\/code>\u7ea2\u9ed1\u6811\u548c\u7b49\u5f85\u94fe\u8868<\/p>\n\n\n\n
\u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
\n
\u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
static int ep_alloc(struct eventpoll **pep)
{
    struct user_struct *user;
    struct eventpoll *ep;
\u200b
    \/* \u8fd4\u56de\u5f53\u524d\u8fdb\u7a0b\u7684\u7528\u6237ID *\/
    user = get_current_user();
    ep = kzalloc(sizeof(*ep), GFP_KERNEL);
\u200b
    \/* \u521d\u59cb\u5316\u4e92\u65a5\u9501 *\/
    mutex_init(&ep->mtx);
    \/* \u521d\u59cb\u5316\u8bfb\u5199\u9501 *\/
    rwlock_init(&ep->lock);
    init_waitqueue_head(&ep->wq);
    init_waitqueue_head(&ep->poll_wait);
    INIT_LIST_HEAD(&ep->rdllist);
    ep->rbr = RB_ROOT_CACHED;
    ep->ovflist = EP_UNACTIVE_PTR;
    ep->user = user;
\u200b
    *pep = ep;
\u200b
    return 0;
}<\/code><\/pre>\n\n\n\n
\u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
ep_alloc<\/code>\u51fd\u6570\u521b\u5efa\u7533\u8bf7\u7ed3\u6784\u4f53\u7684\u5185\u5b58\u7a7a\u95f4\uff0c\u5c06\u7ed3\u6784\u4f53\u7684\u5404\u4e2a\u6210\u5458\u521d\u59cb\u5316\uff0c\u5176\u4e2d\u9700\u8981\u6ce8\u610f\u7684\u662fuser<\/code>\u4fdd\u5b58\u7684\u662f\u5f53\u524d\u8fdb\u7a0b\u5bf9\u5e94\u7684\u7528\u6237ID<\/code><\/p>\n\n\n\n
eventpoll<\/code>\u7ed3\u6784\u56fe<\/strong><\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
2) struct epitem<\/code><\/h4>\n\n\n\n
\u6bcf\u5f53\u6211\u4eec\u8c03\u7528epoll_ctl<\/code>\u589e\u52a0\u4e00\u4e2afd<\/code>\u65f6\uff0c\u5185\u6838\u5c31\u4f1a\u4e3a\u6211\u4eec\u521b\u5efa\u51fa\u4e00\u4e2aepitem<\/code>\u5b9e\u4f8b\uff0c\u5e76\u4e14\u628a\u8fd9\u4e2a\u5b9e\u4f8b\u4f5c\u4e3a\u7ea2\u9ed1\u6811\u7684\u4e00\u4e2a\u5b50\u8282\u70b9\uff0c\u589e\u52a0\u5230eventpoll<\/code>\u7ed3\u6784\u4f53\u4e2d\u7684\u7ea2\u9ed1\u6811\u4e2d\uff0c\u5bf9\u5e94\u7684\u5b57\u6bb5\u662frbr<\/code>\u3002\u8fd9\u4e4b\u540e\uff0c\u67e5\u627e\u6bcf\u4e00\u4e2afd<\/code>\u4e0a\u662f\u5426\u6709\u4e8b\u4ef6\u53d1\u751f\u90fd\u662f\u901a\u8fc7\u7ea2\u9ed1\u6811\u4e0a\u7684epitem<\/code>\u6765\u64cd\u4f5c<\/p>\n\n\n\n
struct epitem {
    union {
        \/* \u7ea2\u9ed1\u6811\u8282\u70b9\u5c06\u6b64\u7ed3\u6784\u94fe\u63a5\u5230eventpoll\u7ea2\u9ed1\u6811 *\/
        struct rb_node rbn;
        \/* RCU\u5934\u90e8\uff0c\u7528\u4e8e\u91ca\u653estruct epitem *\/
        struct rcu_head rcu;
    };
\u200b
    \/* \u6302\u8f7d\u5230eventpoll->rdllist\u7684\u8282\u70b9  *\/
    struct list_head rdllink;
\u200b
    \/* \u6307\u5411eventpoll->ovflist\u7684\u6307\u9488 *\/
    struct epitem *next;
\u200b
    \/* epoll\u76d1\u542c\u7684fd *\/
    struct epoll_filefd ffd;
\u200b
    \/* \u4e00\u4e2a\u6587\u4ef6\u53ef\u4ee5\u88ab\u591a\u4e2aepoll\u5b9e\u4f8b\u6240\u76d1\u542c\uff0c\u8fd9\u91cc\u8bb0\u5f55\u4e86\u5f53\u524d\u6587\u4ef6\u88ab\u76d1\u542c\u7684\u6b21\u6570 *\/
    int nwait;
\u200b
    \/* \u8f6e\u8be2\u7b49\u5f85\u961f\u5217\u7684\u5217\u8868 *\/
    struct list_head pwqlist;
\u200b
    \/* \u5f53\u524depollitem\u6240\u5c5e\u7684eventpoll*\/
    struct eventpoll *ep;
\u200b
    \/* \u5217\u8868\u5934\u6587\u4ef6\uff0c\u7528\u4e8e\u5c06\u8be5\u9879\u94fe\u63a5\u5230\"struct file\"\u7684\u9879\u5217\u8868 *\/ 
    struct list_head fllink;
\u200b
    \/* \u8bbe\u7f6eEPOLLWAKEUP\u6807\u5fd7\u65f6\u4f7f\u7528\u7684\u5524\u9192\u6e90 *\/
    struct wakeup_source __rcu *ws;
\u200b
    \/* \u63cf\u8ff0\u611f\u5174\u8da3\u7684\u4e8b\u4ef6\u548c\u6e90fd\u7684\u7ed3\u6784 *\/
    struct epoll_event event;
};<\/code><\/pre>\n\n\n\n
\u521b\u5efaepitem<\/code>\u8282\u70b9<\/strong><\/p>\n\n\n\n
ep_insert<\/code>\u51fd\u6570<\/p>\n\n\n\n
\/*
 * Must be called with \"mtx\" held.
 *\/
static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
             struct file *tfile, int fd, int full_check)
{
    int error, pwake = 0;
    __poll_t revents;
    long user_watches;
    struct epitem *epi;
    struct ep_pqueue epq;
\u200b
    \/* \u83b7\u53d6\u5f53\u524d\u7528\u6237\u5141\u8bb8\u521b\u5efa\u7684epoll\u76d1\u542c\u6700\u5927\u6570\u91cf *\/
    user_watches = atomic_long_read(&ep->user->epoll_watches);
\u200b
    epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)
\u200b
    INIT_LIST_HEAD(&epi->rdllink);
    INIT_LIST_HEAD(&epi->fllink);
    INIT_LIST_HEAD(&epi->pwqlist);
    epi->ep = ep;
    ep_set_ffd(&epi->ffd, tfile, fd);
    epi->event = *event;
    epi->nwait = 0;
    epi->next = EP_UNACTIVE_PTR;
\u200b
    \/* \u8bbe\u7f6eepoll\u5524\u9192\u6e90 *\/
    if (epi->event.events & EPOLLWAKEUP) {
        error = ep_create_wakeup_source(epi);
        if (error)
            goto error_create_wakeup_source;
    } else {
        RCU_INIT_POINTER(epi->ws, NULL);
    }
\u200b
    epq.epi = epi;
    init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
\u200b
    revents = ep_item_poll(epi, &epq.pt, 1);
\u200b
    error = -ENOMEM;
    if (epi->nwait < 0)
        goto error_unregister;
\u200b
    list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
\u200b
    ep_rbtree_insert(ep, epi);
\u200b
    error = -EINVAL;
    if (full_check && reverse_path_check())
        goto error_remove_epi;
\u200b
    if (revents && !ep_is_linked(epi)) {
        list_add_tail(&epi->rdllink, &ep->rdllist);
        ep_pm_stay_awake(epi);
\u200b
        \/* Notify waiting tasks that events are available *\/
        if (waitqueue_active(&ep->wq))
            wake_up(&ep->wq);
        if (waitqueue_active(&ep->poll_wait))
            pwake++;
    }
\u200b
    \/* \u539f\u5b50\u5730\u589e\u52a0\u5f53\u524d\u7528\u6237\u6216\u8fdb\u7a0b\u4f7f\u7528\u7684 epoll \u76d1\u89c6\u5668\u7684\u8ba1\u6570 *\/
    atomic_long_inc(&ep->user->epoll_watches);
\u200b
    if (pwake)
        ep_poll_safewake(&ep->poll_wait);
\u200b
    return 0;
\u200b
error_remove_epi:
    spin_lock(&tfile->f_lock);
    list_del_rcu(&epi->fllink);
    spin_unlock(&tfile->f_lock);
\u200b
    rb_erase_cached(&epi->rbn, &ep->rbr);
\u200b
error_unregister:
    ep_unregister_pollwait(ep, epi);
\u200b
    \/*
     * We need to do this because an event could have been arrived on some
     * allocated wait queue. Note that we don't care about the ep->ovflist
     * list, since that is used\/cleaned only inside a section bound by \"mtx\".
     * And ep_insert() is called with \"mtx\" held.
     *\/
    write_lock_irq(&ep->lock);
    if (ep_is_linked(epi))
        list_del_init(&epi->rdllink);
    write_unlock_irq(&ep->lock);
\u200b
    wakeup_source_unregister(ep_wakeup_source(epi));
\u200b
error_create_wakeup_source:
    kmem_cache_free(epi_cache, epi);
\u200b
    return error;
}<\/code><\/pre>\n\n\n\n
\u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
\u6574\u4e2a\u51fd\u6570\u53ef\u4ee5\u5206\u4e3a\u524d\u4e2d\u540e\u4e09\u90e8\u5206<\/p>\n\n\n\n
    \n
  1. \u51fd\u6570\u7684\u524d\u534a\u6bb5\u4e3b\u8981\u662f\u521b\u5efastruct epitem *epi<\/code>\u5e76\u5bf9\u5176\u5185\u5bb9\u8fdb\u884c\u586b\u5145\uff0c\u8fd9\u540c\u65f6\u4e5f\u662f\u7ea2\u9ed1\u6811\u8282\u70b9\u7684\u7c7b\u578b<\/li>\n\n\n\n
  2. \u7136\u540e\u5c06epi<\/code>\u6dfb\u52a0\u5230\u7ea2\u9ed1\u6811\u4e2d<\/li>\n\n\n\n
  3. \u5c06\u8282\u70b9\u6dfb\u52a0\u5230\u5bf9\u5e94\u7684\u5c31\u7eea\u94fe\u8868\u3001\u7b49\u5f85\u94fe\u8868\uff0c\u4ee5\u53ca\u8bbe\u7f6e\u56de\u8c03\u51fd\u6570<\/li>\n<\/ol>\n\n\n\n
    epitem<\/code>\u7ed3\u6784\u56fe<\/strong><\/p>\n\n\n\n
    \"\"<\/div><\/figure>\n\n\n\n
    3) struct eppoll_entry<\/code><\/h4>\n\n\n\n
    \u6bcf\u6b21\u5f53\u4e00\u4e2afd<\/code>\u5173\u8054\u5230\u4e00\u4e2aepoll<\/code>\u5b9e\u4f8b\uff0c\u5c31\u4f1a\u6709\u4e00\u4e2aeppoll_entry<\/code>\u4ea7\u751f\uff0c\u7528\u4e8e\u8f6e\u8be2\u94a9\u5b50\u4f7f\u7528\u7684\u7b49\u5f85\u7ed3\u6784<\/p>\n\n\n\n
    \/* Wait structure used by the poll hooks *\/
    struct eppoll_entry
    {
        \/* List header used to link this structure to the \"struct epitem\" *\/
        struct list_head llink;
    \u200b
        \/* The \"base\" pointer is set to the container \"struct epitem\" *\/
        struct epitem *base;
    \u200b
        \/*
         * Wait queue item that will be linked to the target file wait
         * queue head.
         *\/
        wait_queue_entry_t wait;
    \u200b
        \/* The wait queue head that linked the \"wait\" wait queue item *\/
        wait_queue_head_t *whead;
    };<\/code><\/pre>\n\n\n\n
    4.2 epoll<\/code>\u7ea2\u9ed1\u6811\u64cd\u4f5c\u63a5\u53e3<\/h3>\n\n\n\n
    epoll<\/code>\u6a21\u5757\u5728\u5185\u90e8\u7ef4\u62a4\u4e86\u4e00\u4e2a\u7ea2\u9ed1\u6811\u7684\u6570\u636e\u7ed3\u6784\u7528\u6765\u7ba1\u7406epoll<\/code>\u8282\u70b9\uff0c\u7ea2\u9ed1\u6811\u7684\u8282\u70b9\u7c7b\u578b\u4e3astruct epitem<\/code><\/p>\n\n\n\n
    1) \u6a21\u5757\u5bf9\u5916\u603b\u63a5\u53e3<\/h4>\n\n\n\n
    epoll_ctl<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    epoll<\/code>\u6a21\u5757\u63d0\u4f9b\u7684\u4fee\u6539\u5143\u7d20\u7684\u63a5\u53e3\uff0c\u4e3b\u8981\u7528\u4e8e\u4fee\u6539\u7ea2\u9ed1\u6811\u8282\u70b9\u548c\u5404\u4e2a\u5173\u952e\u94fe\u8868<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
            struct epoll_event __user *, event)
    {
        int full_check = 0;
        struct fd tf;
        struct eventpoll *ep;
        struct epitem *epi;
        struct epoll_event epds;
        
        copy_from_user(&epds, event, sizeof(struct epoll_event))\uff1b
        \/*
         * \u63a5\u53e3\u4f7f\u7528\u65f6\u4f1a\u4f20\u5165\u5bf9epoll\u8282\u70b9\u7684\u64cd\u4f5c\u7c7b\u578b
         * \u5305\u62ec\u589e\u5220\u6539\u4e09\u79cd\u64cd\u4f5c\uff0c\u5206\u522b\u5bf9\u5e94\u4e0d\u540c\u63a5\u53e3
         *\/
        switch (op) {
        case EPOLL_CTL_ADD:
            ep_insert(ep, &epds, tf.file, fd, full_check);
            break;
        case EPOLL_CTL_DEL:
            ep_remove(ep, epi);
            break;
        case EPOLL_CTL_MOD:
            ep_modify(ep, epi, &epds);
            break;
        }
    }<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    \u5bf9epoll<\/code>\u8282\u70b9\u7684\u64cd\u4f5c\u4f1a\u9996\u5148\u8fdb\u5165\u8fd9\u4e2a\u51fd\u6570\uff0c\u7136\u540e\u6839\u636e\u4e0d\u540c\u7684\u64cd\u4f5c\u7c7b\u578b\u8fdb\u5165\u4e0d\u540c\u7684\u8282\u70b9<\/p>\n\n\n\n
    \"\"<\/div><\/figure>\n\n\n\n
    2) \u67e5\u627e\u8282\u70b9<\/h4>\n\n\n\n
    ep_find<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u5728\u7ea2\u9ed1\u6811\u4e2d\u67e5\u627e\u8282\u70b9<\/p>\n\n\n\n
    \u6e90\u4ee3\u7801\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u9664\u6ce8\u91ca\u5916\uff0c\u6240\u6709\u4ee3\u7801\u5747\u672a\u5220\u6539<\/p>\n<\/blockquote>\n\n\n\n
    static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
    {
        int kcmp;
        struct rb_node *rbp;
        struct epitem *epi, *epir = NULL;
        struct epoll_filefd ffd;
    \u200b
        \/\/ \u8bbe\u7f6e epoll_filefd \u7ed3\u6784\u4f53\uff0c\u7528\u4e8e\u6bd4\u8f83\u67e5\u627e
        ep_set_ffd(&ffd, file, fd);
        
        \/\/ \u904d\u5386\u7ea2\u9ed1\u6811
        for (rbp = ep->rbr.rb_root.rb_node; rbp; ) {
            \/* \u901a\u8fc7\u7236\u8282\u70b9\u83b7\u53d6\u5bf9\u5e94\u7684 epitem \u7ed3\u6784\u4f53 *\/
            epi = rb_entry(rbp, struct epitem, rbn);
            \/* \u6bd4\u8f83\u5f53\u524d\u8282\u70b9\u4e0e\u8981\u63d2\u5165\u7684\u8282\u70b9 *\/
            kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
             \/* \u5982\u679c\u8981\u63d2\u5165\u8282\u70b9\u7684\u5173\u952e\u5b57\u5927\u4e8e\u5f53\u524d\u8282\u70b9\uff0c\u5219\u5411\u53f3\u5b50\u6811\u67e5\u627e,\u5426\u5219\u5411\u5de6\u5b50\u6811\u67e5\u627e *\/
            if (kcmp > 0)
                rbp = rbp->rb_right;
            else if (kcmp < 0)
                rbp = rbp->rb_left;
            else {
                epir = epi;
                break;
            }
        }
    \u200b
        return epir;
    }<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    \u91c7\u7528\u6df1\u5ea6\u4f18\u5148\u7684\u7b56\u7565\uff0c\u904d\u5386\u7ea2\u9ed1\u6811\u627e\u5230\u76ee\u6807\u8282\u70b9<\/p>\n\n\n\n
    3) \u63d2\u5165\u8282\u70b9<\/h4>\n\n\n\n
    ep_rbtree_insert<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u63d2\u5165\u65b0\u7684\u8282\u70b9<\/p>\n\n\n\n
    \u6e90\u4ee3\u7801\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u9664\u6ce8\u91ca\u5916\uff0c\u6240\u6709\u4ee3\u7801\u5747\u672a\u5220\u6539<\/p>\n<\/blockquote>\n\n\n\n
    static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
    \t\t     struct file *tfile, int fd, int full_check)
    {
    \t...
    \tep_rbtree_insert(ep, epi);
    \t...
    }

    \/* \u662f\u771f\u6b63\u5411\u7ea2\u9ed1\u6811\u4e2d\u63d2\u5165\u8282\u70b9\u7684\u51fd\u6570 *\/
    static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
    {
        int kcmp;
        struct rb_node **p = &ep->rbr.rb_root.rb_node, *parent = NULL;
        struct epitem *epic;
        bool leftmost = true;

        \/* \u904d\u5386\u7ea2\u9ed1\u6811\uff0c\u627e\u5230\u5408\u9002\u7684\u63d2\u5165\u4f4d\u7f6e *\/
        while (*p) {
            parent = *p;
            \/* \u901a\u8fc7\u7236\u8282\u70b9\u83b7\u53d6\u5bf9\u5e94\u7684 epitem \u7ed3\u6784\u4f53 *\/
            epic = rb_entry(parent, struct epitem, rbn);
            \/* \u6bd4\u8f83\u5f53\u524d\u8282\u70b9\u4e0e\u8981\u63d2\u5165\u7684\u8282\u70b9 *\/
            kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd); 
            \/* \u5982\u679c\u8981\u63d2\u5165\u8282\u70b9\u7684\u5173\u952e\u5b57\u5927\u4e8e\u5f53\u524d\u8282\u70b9\uff0c\u5219\u5411\u53f3\u5b50\u6811\u67e5\u627e,\u5426\u5219\u5411\u5de6\u5b50\u6811\u67e5\u627e *\/
            if (kcmp > 0) {
                p = &parent->rb_right;
                leftmost = false; \/\/ \u6807\u8bb0\u4e0d\u662f\u6700\u5de6\u4fa7\u8282\u70b9
            } else {
                p = &parent->rb_left;
            }
        }

        \/* \u5c06\u65b0\u8282\u70b9\u94fe\u63a5\u5230\u7236\u8282\u70b9\u4e0a\uff0c\u5e76\u91cd\u65b0\u5e73\u8861\u7ea2\u9ed1\u6811 *\/ 
        rb_link_node(&epi->rbn, parent, p);
        rb_insert_color_cached(&epi->rbn, &ep->rbr, leftmost);
    }<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    \u91c7\u7528\u6df1\u5ea6\u4f18\u5148\u7684\u7b56\u7565\uff0c\u904d\u5386\u7ea2\u9ed1\u6811\u627e\u5230\u76ee\u6807\u8282\u70b9\uff0c\u7136\u540e\u5c06\u8282\u70b9\u63d2\u5165<\/p>\n\n\n\n
    4) \u5220\u9664\u8282\u70b9<\/h4>\n\n\n\n
    ep_remove<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u4ece\u7ea2\u9ed1\u6811\u4e2d\u5220\u9664\u8282\u70b9<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    static int ep_remove(struct eventpoll *ep, struct epitem *epi)
    {
        ep_unregister_pollwait(ep, epi); \/\/ \u79fb\u9664\u8f6e\u8be2\u7b49\u5f85\u961f\u5217\u94a9\u5b50

        \/* Remove the current item from the list of epoll hooks *\/
        list_del_rcu(&epi->fllink); \/\/ \u4ece epoll \u94a9\u5b50\u5217\u8868\u4e2d\u79fb\u9664\u5f53\u524d epitem

        rb_erase_cached(&epi->rbn, &ep->rbr); \/\/ \u4ece\u4e8b\u4ef6\u8f6e\u8be2\u7684\u7ea2\u9ed1\u6811\u4e2d\u79fb\u9664\u5f53\u524d epitem

        if (ep_is_linked(epi)) \/\/ \u68c0\u67e5\u5f53\u524d epitem \u662f\u5426\u5df2\u7ecf\u94fe\u63a5\u5230\u67d0\u4e2a\u94fe\u8868\u4e2d
            list_del_init(&epi->rdllink); \/\/ \u5982\u679c\u5df2\u94fe\u63a5\uff0c\u5219\u4ece\u4e8b\u4ef6\u8f6e\u8be2\u7684\u94fe\u8868\u4e2d\u79fb\u9664

        wakeup_source_unregister(ep_wakeup_source(epi)); \/\/ \u53d6\u6d88\u5524\u9192\u6e90\u7684\u6ce8\u518c\uff0c\u91ca\u653e\u76f8\u5173\u8d44\u6e90

        atomic_long_dec(&ep->user->epoll_watches); \/\/ \u51cf\u5c11 epoll \u89c2\u5bdf\u6570\u8ba1\u6570\u5668

        return 0; \/\/ \u8fd4\u56de\u6210\u529f\u72b6\u6001
    }<\/code><\/pre>\n\n\n\n
    5) \u4fee\u6539\u8282\u70b9<\/h4>\n\n\n\n
    ep_modify<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u4fee\u6539\u8282\u70b9<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    \/*
     * Modify the interest event mask by dropping an event if the new mask
     * has a match in the current file status. Must be called with \"mtx\" held.
     *\/
    static int ep_modify(struct eventpoll *ep, struct epitem *epi,
    \t\t     const struct epoll_event *event)
    {
    \tint pwake = 0;
    \tpoll_table pt;

    \tlockdep_assert_irqs_enabled();

    \tinit_poll_funcptr(&pt, NULL);

    \tepi->event.events = event->events;
    \tepi->event.data = event->data;
    \t\/*
    \t * \u68c0\u67e5\u5f53\u524d\u8282\u70b9\u662f\u5426\u8bbe\u7f6e\u4e86EPOLLWAKEUP,\u5982\u679c\u8bbe\u7f6e\u4e86,\u4e14\u5f53\u524d epitem \u6ca1\u6709\u5524\u9192\u6e90,\u5219\u521b\u5efa\u4e00\u4e2a;
    \t * \u5982\u679c\u672a\u8bbe\u7f6e,\u4e14\u5f53\u524d\u6709\u5524\u9192\u6e90,\u5219\u9500\u6bc1\u5b83
    \t *\/
    \tif (epi->event.events & EPOLLWAKEUP) {
    \t\tif (!ep_has_wakeup_source(epi))
    \t\t\tep_create_wakeup_source(epi);
    \t} else if (ep_has_wakeup_source(epi)) {
    \t\tep_destroy_wakeup_source(epi);
    \t}

    \t\/* \u901a\u8fc7vfs_poll\u6216\u68c0\u67e5rdllink\u94fe\u8868\uff0c\u5224\u65ad\u5f53\u524d\u8282\u70b9\u662f\u5426\u51c6\u5907\u5c31\u7eea *\/
    \tif (ep_item_poll(epi, &pt, 1)) {\t
    \t\tif (!ep_is_linked(epi)) {\t\t\/* \u68c0\u67e5\u5f53\u524d\u63a5\u8282\u70b9\u662f\u5426\u94fe\u63a5\u5230rdllink\u94fe\u8868\u4e0a *\/
    \t\t\tlist_add_tail(&epi->rdllink, &ep->rdllist);
    \t\t\tep_pm_stay_awake(epi);\t\t\/* \u4fdd\u6301epoll\u6d3b\u8dc3 *\/

    \t\t\tif (waitqueue_active(&ep->wq))
    \t\t\t\twake_up(&ep->wq);
    \t\t\tif (waitqueue_active(&ep->poll_wait))
    \t\t\t\tpwake++;
    \t\t}
    \t}

    \tif (pwake)
    \t\tep_poll_safewake(&ep->poll_wait);

    \treturn 0;
    }<\/code><\/pre>\n\n\n\n
    4.3 \u5173\u952e\u94fe\u8868\u53ca\u76f8\u5173\u63a5\u53e3<\/h3>\n\n\n\n
    1) epitem->ovflist<\/code>\u94fe\u8868\u548cepitem->rdlink<\/code>\u94fe\u8868<\/h4>\n\n\n\n
    \u626b\u63cf\u5c31\u7eea\u94fe\u8868<\/h4>\n\n\n\n
    ep_scan_ready_list<\/code><\/strong>\u51fd\u6570<\/p>\n\n\n\n
    \u626b\u63cf\u5c31\u7eea\u94fe\u8868\u6838\u5fc3\u63a5\u53e3\uff0c\u7528\u4e8e\u7ef4\u62a4\u66f4\u65b0epoll<\/code>\u5173\u952e\u94fe\u8868\u7684\u72b6\u6001<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    static __poll_t ep_scan_ready_list(struct eventpoll *ep,
    \t\t\t      __poll_t (*sproc)(struct eventpoll *,
    \t\t\t\t\t   struct list_head *, void *),
    \t\t\t      void *priv, int depth, bool ep_locked)
    {
    \t__poll_t res;
    \tint pwake = 0;
    \tstruct epitem *epi, *nepi;

        \/*
         * \u521b\u5efa\u4e00\u4e2a\u7a7a\u7684\u65b0\u94fe\u8868txlist\uff0c\u5c06\u5176\u548cep->rdllist\u62fc\u63a5\u8d77\u6765
         * \u6b64\u5904\u4f20\u5165\u7684sproc\u662fep_read_events_proc\u6216ep_send_events_proc\u7528\u4e8e\u68c0\u6d4b\u53e5\u67c4\u7684\u72b6\u6001\u6216\u662f\u5c06epoll\u68c0\u6d4b\u7ed3\u679c\u4ece\u5185\u6838\u53d1\u7ed9\u7528\u6237\u6001
         *\/
    \tLIST_HEAD(txlist);
    \tlist_splice_init(&ep->rdllist, &txlist);
    \tWRITE_ONCE(ep->ovflist, NULL);
    \tres = (*sproc)(ep, &txlist, priv);

        \/*
         * \u51fd\u6570\u540e\u534a\u6bb5
         * \u6b64\u6b21\u5f00\u59cb\u5bf9ep->ovflist\u8fdb\u884c\u626b\u63cf\uff0c\u5f53ep->ovflist->rdllink\u4e2d\u53ea\u6709\u4e00\u4e2a\u5143\u7d20
         * \u65f6\u5c06\u5176\u6dfb\u52a0\u5230ep->rdllist\u4e2d\u5e76\u5524\u9192\u8fd9\u4e2aepi\u8282\u70b9
         *\/
    \tfor (nepi = READ_ONCE(ep->ovflist); (epi = nepi) != NULL;
    \t     nepi = epi->next, epi->next = EP_UNACTIVE_PTR) {
    \t\tif (!ep_is_linked(epi)) {
    \t\t\tlist_add(&epi->rdllink, &ep->rdllist);
    \t\t\tep_pm_stay_awake(epi);
    \t\t}
    \t}

        \/* \u6e05\u7a7aep->ovflist\u94fe\u8868 *\/
    \tWRITE_ONCE(ep->ovflist, EP_UNACTIVE_PTR);

        \/* \u5c06txlist\u6dfb\u52a0\u5230ep->rdllist *\/
    \tlist_splice(&txlist, &ep->rdllist);
    \t__pm_relax(ep->ws);

        \/* \u5524\u9192\u94fe\u8868 *\/
    \tif (!list_empty(&ep->rdllist)) {
    \t\tif (waitqueue_active(&ep->wq))
    \t\t\twake_up(&ep->wq);
    \t\tif (waitqueue_active(&ep->poll_wait))
    \t\t\tpwake++;
    \t}

    \tif (pwake)
    \t\tep_poll_safewake(&ep->poll_wait);

    \treturn res;
    }<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    ep_scan_ready_list<\/code>\u51fd\u6570\u7684\u6267\u884c\u53ef\u4ee5\u5206\u4e3a\u524d\u540e\u4e24\u4e2a\u90e8\u5206<\/p>\n\n\n\n
    \u524d\u534a\u90e8\u5206\uff1a\u6267\u884c\u4f20\u5165\u7684\u51fd\u6570\u6307\u9488sproc<\/code>\u8fd9\u91cc\u4f1a\u6839\u636e\u4e0d\u540c\u7684\u573a\u666f\u4f20\u5165ep_read_events_proc<\/code>\u6216ep_send_events_proc<\/code>\uff0c\u5206\u522b\u7528\u4e8e\u68c0\u67e5epoll<\/code>\u5c31\u7eea\u94fe\u8868\u6216\u5c06epoll<\/code>\u68c0\u6d4b\u7ed3\u679c\u4ece\u5185\u6838\u6001\u53d1\u9001\u81f3\u7528\u6237\u6001<\/p>\n\n\n\n
    \u540e\u534a\u90e8\u5206\uff1a\u904d\u5386\u68c0\u67e5ovflist<\/code>\u94fe\u8868\uff0c\u6839\u636e\u68c0\u67e5\u7ed3\u679c\u66f4\u65b0rdllist<\/code>\u94fe\u8868\uff0c\u7136\u540e\u5524\u9192\u7b49\u5f85\u94fe\u8868<\/p>\n\n\n\n
    2) \u7b49\u5f85\u94fe\u8868\u548c\u5c31\u7eea\u94fe\u8868<\/h4>\n\n\n\n
    epitem->rdlink<\/code>\u94fe\u8868\u548ceventpoll->rdllist<\/code>\u94fe\u8868<\/strong><\/p>\n\n\n\n
    epitem->rdlink<\/code>\u4e2d\u5b58\u653e\u7b49\u5f85\u7684\u4e8b\u4ef6\uff0ceventpoll->rdllist<\/code>\u4e2d\u5b58\u653e\u5df2\u7ecf\u5c31\u7eea\u7684\u4e8b\u4ef6<\/p>\n\n\n\n
    static __poll_t ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
    \t\t\t       void *priv)
    {
        ...
        struct epitem *epi;

        \/* \u5c06epi->rdllink\u63d2\u5165ep->rdllist\u5c3e\u90e8 *\/
    \tlist_add_tail(&epi->rdllink, &ep->rdllist);
    \t...
    }<\/code><\/pre>\n\n\n\n
    \u7b49\u5f85\u94fe\u8868\u5173\u7cfb\u56fe<\/strong><\/p>\n\n\n\n
    \"\"<\/div><\/figure>\n\n\n\n
    3) eventpoll->wq\u7b49\u5f85\u961f\u5217\u94fe\u8868<\/h4>\n\n\n\n
    \u51fd\u6570\u8c03\u7528\u6808<\/p>\n\n\n\n
    ep_poll
        \/* \u6b64\u5904\u8bbe\u7f6e\u7684\u5524\u9192\u56de\u8c03\u51fd\u6570\u662fdefault_wake_function,\u7528\u4e8e\u5524\u9192\u8fdb\u7a0b *\/
    \t->init_waitqueue_entry(&wait, current)
        \/* \u5c06wait\u6dfb\u52a0\u5230eventpoll->wq\u94fe\u8868\u4e2d *\/
    \t->__add_wait_queue_exclusive(&ep->wq, &wait)
    \t\t->__add_wait_queue(wq_head, wq_entry)
    \t\t\t->list_add(&wq_entry->entry, &wq_head->head)
    \t->__remove_wait_queue(&ep->wq, &wait)
        
    ep_ptable_queue_proc
        \/* \u6b64\u5904\u8bbe\u7f6e\u7684\u5524\u9192\u56de\u8c03\u51fd\u6570\u662fep_poll_callback,\u6700\u7ec8\u4f7f\u7528wake_up(&ep->wq)\u5524\u9192epoll *\/
        ->init_waitqueue_func_entry(&pwq->wait, ep_poll_callback)
    \t->add_wait_queue(whead, &pwq->wait)<\/code><\/pre>\n\n\n\n
    \u6b64\u5904\u6ce8\u518c\u5524\u9192\u51fd\u6570\u540e\u4f1a\u901a\u8fc7wake_up<\/code>\u63a5\u53e3\u6765\u8c03\u7528<\/p>\n\n\n\n
    ->__wake_up
        ->__wake_up_common_lock 
            ->__wake_up_common
                ->curr = list_next_entry(bookmark, entry);
                ->curr->func(curr, mode, wake_flags, key);<\/code><\/pre>\n\n\n\n
    \u4e94\u3001\u5bf9\u6587\u4ef6\u53e5\u67c4\u7684\u76d1\u542c<\/h2>\n\n\n\n
    5.1 \u9a71\u52a8\u5c42\u9762\u5bf9\u6587\u4ef6\u7cfb\u7edf\u7684\u76d1\u542c<\/h3>\n\n\n\n
    file_operations->poll<\/code>\u63a5\u53e3<\/strong><\/p>\n\n\n\n
    \u51fd\u6570\u58f0\u660e<\/strong><\/p>\n\n\n\n
    \u5728linux-5.4\\include\\linux\\fs.h<\/code>\u4e2d\u53ef\u4ee5\u770b\u5230struct file_operations<\/code>\u7684\u5b9a\u4e49<\/p>\n\n\n\n
    #define __bitwise __attribute__((bitwise))
    typedef unsigned __bitwise __poll_t;

    struct file_operations {
    \t...
        \/* read\u610f\u4e3a\u8bfb\u3001write\u610f\u4e3a\u5199\u3001poll\u610f\u4e3a\u68c0\u6d4b\uff0c\u63a2\u8be2 *\/
        ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
    \tssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
    \t__poll_t (*poll) (struct file *, struct poll_table_struct *);
    \t...
    } __randomize_layout;<\/code><\/pre>\n\n\n\n
    \u51fd\u6570\u5b9e\u73b0<\/strong><\/p>\n\n\n\n
    struct file_operations<\/code>\u4e2d\u7684__poll_t<\/code>\u662f\u5728\u9a71\u52a8\u4ee3\u7801\u4e2d\u5b9e\u73b0\uff0c\u4e0d\u540c\u9a71\u52a8\u4ee3\u7801\u5b9e\u73b0\u65b9\u5f0f\u4e0d\u540c\u3002\u4f46\u90fd\u4f1a\u8c03\u7528poll_wait()<\/code>\u51fd\u6570<\/p>\n\n\n\n
    \u5728\u6b64\u5904\u5217\u51fa\u4f8b\u5b50<\/p>\n\n\n\n
    \u5728linux-5.4\\arch\\powerpc\\platforms\\powernv\\opal-prd.c<\/code>\u4e2d\u53ef\u4ee5\u627e\u5230OPAL<\/code>\u7684\u9a71\u52a8\u5bf9\u4e8epoll<\/code>\u7684\u5b9e\u73b0<\/p>\n\n\n\n
    static const struct file_operations opal_prd_fops = {
    \t...
    \t.poll\t\t= opal_prd_poll,
    \t...
    };

    static __poll_t opal_prd_poll(struct file *file,
    \t\tstruct poll_table_struct *wait)
    {
    \tpoll_wait(file, &opal_prd_msg_wait, wait);

    \tif (!opal_msg_queue_empty())
    \t\treturn EPOLLIN | EPOLLRDNORM;

    \treturn 0;
    }<\/code><\/pre>\n\n\n\n
    \u5728linux-5.4\\arch\\powerpc\\kernel\\rtasd.c<\/code>\u4e2d\u53ef\u4ee5\u627e\u5230RTASD<\/code>\u7684\u9a71\u52a8\u5bf9\u4e8epoll<\/code>\u7684\u5b9e\u73b0<\/p>\n\n\n\n
    static __poll_t rtas_log_poll(struct file *file, poll_table * wait)
    {
    \tpoll_wait(file, &rtas_log_wait, wait);
    \tif (rtas_log_size)
    \t\treturn EPOLLIN | EPOLLRDNORM;
    \treturn 0;
    }

    static const struct file_operations proc_rtas_log_operations = {
    \t...
    \t.poll =\t\trtas_log_poll,
    \t...
    };<\/code><\/pre>\n\n\n\n
    \u53ef\u4ee5\u770b\u5230\u4e0d\u540c\u7684\u9a71\u52a8\u4ee3\u7801\u4e2d\u90fd\u8c03\u7528\u4e86poll_wait()<\/code>\uff0c\u628a\u5f53\u524d\u8fdb\u7a0b\u52a0\u5165\u5230\u9a71\u52a8\u91cc\u81ea\u5b9a\u4e49\u7684\u7b49\u5f85\u961f\u5217\u4e0a\uff0c\u5f53\u9a71\u52a8\u4e8b\u4ef6\u5c31\u7eea\u540e\uff0c\u5c31\u53ef\u4ee5\u5728\u9a71\u52a8\u91cc\u81ea\u5b9a\u4e49\u7684\u7b49\u5f85\u961f\u5217\u4e0a\u5524\u9192\u8c03\u7528poll<\/code>\u7684\u8fdb\u7a0b\u3002<\/p>\n\n\n\n
    \u5185\u6838\u7b49\u5f85\u961f\u5217<\/h3>\n\n\n\n
    \u7b49\u5f85\u961f\u5217\u57fa\u672c\u6d41\u7a0b\u5982\u4e0b<\/p>\n\n\n\n
    \u5728select<\/code>\u548cpoll<\/code>\u6a21\u5757\u4e2d\u81ea\u5df1\u5b9e\u73b0\u4e86pollwake<\/code>\u51fd\u6570\u4f5c\u4e3a\u7b49\u5f85\u961f\u5217\u56de\u8c03<\/p>\n\n\n\n
    \"\"<\/div><\/figure>\n\n\n\n
    5.2 epoll<\/code>\u5bf9\u76d1\u542c\u6587\u4ef6\u53e5\u67c4\u7684\u5b9e\u73b0<\/h3>\n\n\n\n
    \u5173\u952e\u56de\u8c03\u51fd\u6570\u7684\u6ce8\u518c<\/strong><\/p>\n\n\n\n
    file_operations.poll<\/code>\u7684\u6ce8\u518c<\/strong><\/p>\n\n\n\n
    \u9996\u5148\u901a\u8fc7init_poll_funcptr<\/code>\u63a5\u53e3\u6ce8\u518c\u5c06\u56de\u8c03\u51fd\u6570\u5199\u5165struct ep_pqueue->poll_table->_qproc<\/code><\/p>\n\n\n\n
    static int ep_insert(...)
    {
        ...
    \tstruct ep_pqueue epq;
        ...
        init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
        ...
    }<\/code><\/pre>\n\n\n\n
    \u5728poll_wait<\/code>\u63a5\u53e3\u4e2d\u4f1a\u4f7f\u7528\u521a\u624d\u6ce8\u518c\u7684ep_ptable_queue_proc<\/code>\u8fd9\u4e2a\u56de\u8c03<\/p>\n\n\n\n
    static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
    {
    \tif (p && p->_qproc && wait_address)
    \t\tp->_qproc(filp, wait_address, p);
    }<\/code><\/pre>\n\n\n\n
    epoll<\/code>\u5bf9\u4e8efile_operations->poll<\/code>\u91c7\u7528\u4e86\u81ea\u5df1\u4e00\u5957\u5b9e\u73b0\u65b9\u5f0f\uff0c\u5176\u4e2d\u4e0e\u9a71\u52a8\u4ee3\u7801\u4e0d\u540c\uff0c\u5e76\u672a\u91c7\u7528poll_wait<\/code>\u5c06\u8fdb\u7a0b\u6302\u8f7d\u5230\u5185\u6838\u7b49\u5f85\u94fe\u4e2d<\/p>\n\n\n\n
    \/* File callbacks that implement the eventpoll file behaviour *\/
    static const struct file_operations eventpoll_fops = {
    #ifdef CONFIG_PROC_FS
    \t.show_fdinfo\t= ep_show_fdinfo,
    #endif
    \t.release\t= ep_eventpoll_release,
    \t.poll\t\t= ep_eventpoll_poll,
    \t.llseek\t\t= noop_llseek,
    };<\/code><\/pre>\n\n\n\n
    vfs_poll<\/code>\u63a5\u53e3\u7684\u5b9e\u73b0<\/strong><\/p>\n\n\n\n
    \u5728vfs_poll<\/code>\u63a5\u53e3\u4e2d\u4f1a\u8c03\u7528\u521a\u624d\u6ce8\u518c\u7684ep_eventpoll_poll<\/code><\/p>\n\n\n\n
    static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt)
    {
    \tif (unlikely(!file->f_op->poll))
    \t\treturn DEFAULT_POLLMASK;
    \treturn file->f_op->poll(file, pt);
    }<\/code><\/pre>\n\n\n\n
    \u5bf9\u5916\u5173\u952e\u63a5\u53e3<\/strong><\/p>\n\n\n\n
    \u5728ep_item_poll<\/code>\u63a5\u53e3\u4e2d\u5b9e\u73b0\u5bf9\u6587\u4ef6\u7684\u76d1\u542c\u63a5\u53e3\uff0c\u6839\u636e\u4e0d\u540c\u60c5\u51b5\u5206\u522b\u4f7f\u7528vfs_poll<\/code>\u6216\u662fep_scan_ready_list<\/code>\u6765\u83b7\u53d6\u53e5\u67c4\u72b6\u6001<\/p>\n\n\n\n
    \/*
     * Differs from ep_eventpoll_poll() in that internal callers already have
     * the ep->mtx so we need to start from depth=1, such that mutex_lock_nested()
     * is correctly annotated.
     *\/
    static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt,
    \t\t\t\t int depth)
    {
    \tstruct eventpoll *ep;
    \tbool locked;

    \tpt->_key = epi->event.events;
    \tif (!is_file_epoll(epi->ffd.file))
    \t\treturn vfs_poll(epi->ffd.file, pt) & epi->event.events;

    \tep = epi->ffd.file->private_data;
    \tpoll_wait(epi->ffd.file, &ep->poll_wait, pt);
    \tlocked = pt && (pt->_qproc == ep_ptable_queue_proc);

    \treturn ep_scan_ready_list(epi->ffd.file->private_data,
    \t\t\t\t  ep_read_events_proc, &depth, depth,
    \t\t\t\t  locked) & epi->event.events;
    }<\/code><\/pre>\n\n\n\n
    \u516d\u3001\u5173\u952e\u6d41\u7a0b\u56de\u8c03\u51fd\u6570<\/h2>\n\n\n\n
    1) ep_poll_safewake<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    \u5524\u9192\u7b49\u5f85eventpoll<\/code>\u6587\u4ef6\u7684\u72b6\u6001\u5c31\u7eea\u7684\u8fdb\u7a0b<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    #define wake_up_poll(x, m)\t\t\t\t\t\t\t\\
    \t__wake_up(x, TASK_NORMAL, 1, poll_to_key(m))

    static void ep_poll_safewake(wait_queue_head_t *wq)
    {
    \twake_up_poll(wq, EPOLLIN);
    }<\/code><\/pre>\n\n\n\n
    2) ep_poll_callback<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    epoll<\/code>\u56de\u8c03\u51fd\u6570<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    static int ep_poll_callback(wait_queue_entry_t *wait,
                                unsigned mode, int sync, void *key)
    {
    }<\/code><\/pre>\n\n\n\n
    3) ep_create_wakeup_source<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    \u521b\u5efa\u5524\u9192\u6e90<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    static int ep_create_wakeup_source(struct epitem *epi)
    {
    }<\/code><\/pre>\n\n\n\n
    4) ep_destroy_wakeup_source<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    \u9500\u6bc1\u5524\u9192\u6e90<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    \/* rare code path, only used when EPOLL_CTL_MOD removes a wakeup source *\/
    static noinline void ep_destroy_wakeup_source(struct epitem *epi)
    {
    }<\/code><\/pre>\n\n\n\n
    5) ep_ptable_queue_proc<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    \u5c06\u7b49\u5f85\u961f\u5217\u6dfb\u52a0\u5230\u76ee\u6807\u6587\u4ef6\u5524\u9192\u5217\u8868\u4e2d\u7684\u56de\u8c03\u51fd\u6570<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
    \t\t\t\t poll_table *pt)
    {
    }<\/code><\/pre>\n\n\n\n
    6) poll_wait<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    \u6ce8\u518c\u7b49\u5f85\u51fd\u6570\uff0c\u5c06\u7b49\u5f85\u7684\u56de\u8c03\u51fd\u6570\u6ce8\u518c\u5230\u5f53\u524d\u8fdb\u7a0b\u4e2d\uff0c\u5728ep_insert<\/code>\u4e2d\u4f7f\u7528<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    \/* 
     * structures and helpers for f_op->poll implementations
     *\/
    typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);

    typedef struct poll_table_struct {
    \tpoll_queue_proc _qproc;
    \t__poll_t _key;
    } poll_table;


    static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
    {
    \tif (p && p->_qproc && wait_address)
    \t\tp->_qproc(filp, wait_address, p);
    }<\/code><\/pre>\n\n\n\n
    7) ep_send_events_proc<\/code>\u51fd\u6570<\/h3>\n\n\n\n
    \u5c06events<\/code>\u4e8b\u4ef6\u4ece\u5185\u6838\u7a7a\u95f4\u53d1\u9001\u5230\u7528\u6237\u7a7a\u95f4<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    static __poll_t ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
    \t\t\t       void *priv)
    {
    }<\/code><\/pre>\n\n\n\n
    \u4e03\u3001epoll<\/code>\u57fa\u672c\u6d41\u7a0b<\/h2>\n\n\n\n
    7.1 epoll<\/code>\u57fa\u672c\u6d41\u7a0b<\/strong><\/h3>\n\n\n\n
    \"\"<\/div><\/figure>\n\n\n\n
    7.2 \u521b\u5efaepoll\u5b9e\u4f8b\u63a5\u53e3<\/h3>\n\n\n\n
    epoll_create1<\/code>\u548cepoll_create<\/code>\u63a5\u53e3\u5747\u53ef\u7528\u4e8e\u521b\u5efaepoll<\/code>\u5b9e\u4f8b\uff0c\u4e0d\u540c\u7684\u662fepoll_create1<\/code>\u53ef\u4ee5\u591a\u4f20\u5165\u4e00\u4e2a\u53c2\u6570<\/p>\n\n\n\n
    SYSCALL_DEFINE1(epoll_create1, int, flags)
    {
    \treturn do_epoll_create(flags);
    }

    SYSCALL_DEFINE1(epoll_create, int, size)
    {
    \tif (size <= 0)
    \t\treturn -EINVAL;

    \treturn do_epoll_create(0);
    }<\/code><\/pre>\n\n\n\n
    do_epoll_create<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u521b\u5efa\u65b0\u7684epoll<\/code>\u8282\u70b9<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    \/* File callbacks that implement the eventpoll file behaviour *\/
    static const struct file_operations eventpoll_fops = {
    \t.show_fdinfo\t= ep_show_fdinfo,
    \t.release\t\t= ep_eventpoll_release,
    \t.poll\t\t\t= ep_eventpoll_poll,
    \t.llseek\t\t\t= noop_llseek,
    };

    \/*
     * anon_inode_getfile-\u901a\u8fc7\u8fde\u63a5\u4e00\u4e2a\u533f\u540dinode\u548c\u4e00\u4e2a\u63cf\u8ff0\u6587\u4ef6\u201c\u7c7b\u201d\u7684dentry\u6765\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u6587\u4ef6\u5b9e\u4f8b
     * @name:\u65b0\u6587\u4ef6\u7684\u201c\u7c7b\u201d\u7684\u540d\u79f0
     * @fops:\u6587\u4ef6\u64cd\u4f5c\u7684\u65b0\u6587\u4ef6
     * @priv:\u65b0\u6587\u4ef6\u7684\u79c1\u6709\u6570\u636e(\u5c06\u662f\u6587\u4ef6\u7684private_data)
     * @flags:\u6253\u5f00\u6587\u4ef6\u7684\u884c\u4e3a\u548c\u5c5e\u6027
     *
     * \u901a\u8fc7\u5c06\u4e00\u4e2a\u6587\u4ef6\u6302\u63a5\u5728\u5355\u4e2a\u7d22\u5f15\u8282\u70b9\u4e0a\u6765\u521b\u5efa\u4e00\u4e2a\u65b0\u6587\u4ef6\u3002\u8fd9\u5bf9\u4e8e\u4e0d\u9700\u8981\u5b8c\u6574inode\u5c31\u53ef\u4ee5\u6b63\u786e\u64cd\u4f5c\u7684\u6587\u4ef6\u5f88\u6709\u7528\u3002
     * \u4f7f\u7528anon_inode_getfile()\u521b\u5efa\u7684\u6240\u6709\u6587\u4ef6\u5c06\u5171\u4eab\u4e00\u4e2ainode\uff0c\u4ece\u800c\u8282\u7701\u5185\u5b58\u5e76\u907f\u514d\u6587\u4ef6\/inode\/dentry\u8bbe\u7f6e\u7684\u4ee3\u7801\u91cd\u590d\u3002\u8fd4\u56de\u65b0\u521b\u5efa\u7684\u6587\u4ef6*\u6216\u9519\u8bef\u6307\u9488\u3002
     *\/
    struct file *anon_inode_getfile(const char *name, const struct file_operations *fops, void *priv, int flags);

    static int do_epoll_create(int flags)
    {
    \tint error, fd;
    \tstruct eventpoll *ep = NULL;
    \tstruct file *file;

    \tep_alloc(&ep);

       \t\/\/ \u83b7\u53d6\u4e00\u4e2a\u53ef\u8bfb\u53ef\u5199\u7684\u672a\u88ab\u4f7f\u7528\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
    \tfd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC));
        \/\/ \u521b\u5efa\u4e00\u4e2a\u533f\u540d\u7684inode\u8282\u70b9
    \tfile = anon_inode_getfile(\"[eventpoll]\", &eventpoll_fops, ep, O_RDWR | (flags & O_CLOEXEC));

        ep->file = file;
    \tfd_install(fd, file);

    \treturn fd;
    }<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    \u521b\u5efainode<\/code>\u8282\u70b9<\/strong><\/p>\n\n\n\n
    \u521b\u5efa\u4e00\u4e2a\u533f\u540d\u7684inode<\/code>\u8282\u70b9\uff0c\u8fd9\u4e2a\u6587\u4ef6\u5bf9\u8c61\u901a\u5e38\u4e0d\u5bf9\u5e94\u4e8e\u5b9e\u9645\u7684\u6587\u4ef6\u7cfb\u7edf\u4e2d\u7684\u4efb\u4f55\u6587\u4ef6\uff0c\u56e0\u6b64\u88ab\u79f0\u4e3a\u533f\u540dinode<\/code>\u3002\u5b83\u88ab\u7528\u4f5cepoll<\/code>\u5b9e\u4f8b\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u901a\u8fc7\u8fd9\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\uff0c\u7528\u6237\u7a7a\u95f4\u7a0b\u5e8f\u53ef\u4ee5\u5bf9epoll<\/code>\u5b9e\u4f8b\u8fdb\u884cI\/O<\/code>\u64cd\u4f5c\u3002\u5e76\u8fd4\u56de\u4e0e\u4e4b\u5173\u8054\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26<\/p>\n\n\n\n
    \u4f7f\u7528anon_inode_getfile<\/code>\u521b\u5efainode<\/code>\u8282\u70b9<\/strong>\uff0c\u6b64\u5904\u4e0d\u8be6\u7ec6\u5c55\u5f00\u5b9e\u73b0\u4ee3\u7801\uff0c\u4ec5\u5217\u51fa\u51fd\u6570\u8c03\u7528\u6808<\/p>\n\n\n\n
    \/* \u5c06\u65b0\u5efa\u7684file->private_data\u8d4b\u503c\u4e3apriv *\/
    |->anon_inode_getfile(const char *name, const struct file_operations *fops, 
                          void *priv, int flags)
    \t\/* \u8bbe\u7f6e\u65b0\u5efa\u7684file\u7684\u540d\u79f0\u4e3a\u4e4b\u524d\u4f20\u5165\u7684name*\/
    \t|->alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt, const char *name, int flags,
                             const struct file_operations *fops)
    \t\t\/* \u5c06\u65b0\u5efa\u7684file->f_op\u8d4b\u503c\u4e3a\u5165\u53c2eventpoll_fops *\/
    \t\t|->alloc_file(const struct path *path, int flags, const struct file_operations *fop)
    \t\t\t\/* \u521b\u5efa\u4e00\u4e2a\u7a7a\u7684file\u5bf9\u8c61\uff0c\u8bbe\u7f6e\u88ab\u521b\u5efa\u6587\u4ef6\u7684\u72b6\u6001\u548c\u5c5e\u6027\u4e3aflags *\/
    \t\t\t|->alloc_empty_file(int flags, const struct cred *cred)<\/code><\/pre>\n\n\n\n
    \u4f7f\u7528fd_install<\/code>\u5c06\u65b0\u521b\u5efa\u7684inode<\/code>\u8282\u70b9\u63d2\u5165\u5f53\u524d\u8fdb\u7a0b\u7684\u6587\u4ef6\u6570\u7ec4\u4e2d<\/strong><\/p>\n\n\n\n
    void fd_install(unsigned int fd, struct file *file)
    {
        \/* current->files\u662f\u6307\u5411\u5f53\u524d\u8fdb\u7a0b\u6587\u4ef6\u63cf\u8ff0\u7b26\u8868\u7684\u6307\u9488 *\/
    \t__fd_install(current->files, fd, file);
    }

    \/* fd:\u6587\u4ef6\u63cf\u8ff0\u7b26
     * file:\u65b0\u5efa\u7684inode\u8282\u70b9
     * struct fdtable\uff1a\u5185\u6838\u4e2d\u7528\u6765\u7ba1\u7406\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u6570\u636e\u7ed3\u6784
     * fdt->fd\uff1a\u5b58\u50a8file\u7ed3\u6784\u4f53\u7684\u6570\u7ec4\uff1a
     *\/
    void __fd_install(struct files_struct *files, unsigned int fd, struct file *file)
    {
    \tstruct fdtable *fdt;
        fdt = files_fdtable(files);
        rcu_assign_pointer(fdt->fd[fd], file);
    }<\/code><\/pre>\n\n\n\n
    \u6b64\u5904\u5c06\u65b0\u5efa\u7684file<\/code>\u8282\u70b9\u63d2\u5165\uff0c\u5bf9\u5e94\u5f53\u524d\u7684\u8fdb\u7a0b\u6587\u4ef6\u6570\u7ec4\u4e2d\uff0c\u7528\u4e8e\u540e\u7eed\u5185\u6838\u7ba1\u7406\u3002<\/p>\n\n\n\n
    \u5c06\u5176\u63d2\u5165ep<\/code>\u4e2d\uff0c\u6b64\u65f6\u7684ep<\/code>\u662f\u5b58\u653e\u5728\u7b49\u5f85\u961f\u5217\u4e2d\u7684<\/p>\n\n\n\n
    \"\"<\/div><\/figure>\n\n\n\n
    7.3 \u64cd\u4f5c\u76d1\u542c\u53e5\u67c4<\/h3>\n\n\n\n
    epoll_ctl<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u7528\u4e8e\u5411epoll<\/code>\u5b9e\u4f8b\u4e2d\u6dfb\u52a0\u3001\u4fee\u6539\u6216\u5220\u9664\u611f\u5174\u8da3\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\uff08socket<\/code>\u3001\u6587\u4ef6\u7b49\uff09\u53ca\u5176\u5173\u6ce8\u7684\u4e8b\u4ef6<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    \/*
     * @epfd: epool_create\u521b\u5efa\u7684\u7528\u4e8eeventpoll\u7684fd
     * @op: \u63a7\u5236\u7684\u547d\u4ee4\u7c7b\u578b
     * EPOLL_CTL_ADD\uff1a\u6dfb\u52a0\u4e00\u4e2a\u65b0\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u548c\u5176\u5173\u6ce8\u7684\u4e8b\u4ef6\u5230 epoll \u5b9e\u4f8b\u4e2d\u3002
     * EPOLL_CTL_MOD\uff1a\u4fee\u6539\u4e00\u4e2a\u5df2\u7ecf\u5b58\u5728\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u5173\u6ce8\u7684\u4e8b\u4ef6\u3002
     * EPOLL_CTL_DEL\uff1a\u4ece epoll \u5b9e\u4f8b\u4e2d\u5220\u9664\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002
     *
     * @fd: \u8981\u64cd\u4f5c\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26
     * @event:\u4e0efd\u76f8\u5173\u7684\u5bf9\u8c61,\u63cf\u8ff0\u4e86\u8981\u6dfb\u52a0\u3001\u4fee\u6539\u6216\u5220\u9664\u7684\u4e8b\u4ef6\u3002
     *\/
    SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
                    struct epoll_event __user *, event)
    {
    \tint error;
    \tint full_check = 0;
    \tstruct fd f, tf;
    \tstruct eventpoll *ep;
    \tstruct epitem *epi;
    \tstruct epoll_event epds;

    \t\/* \u4ece\u7528\u6237\u7a7a\u95f4\u62f7\u8d1devent\u81f3\u5185\u6838\u7a7a\u95f4 *\/
    \tcopy_from_user(&epds, event, sizeof(struct epoll_event));
        tf = fdget(fd);

        if (ep_op_has_event(op))
            ep_take_care_of_epollwakeup(&epds);

        ep = f.file->private_data
        \/*
         * \u53e5\u67c4epfd\u5bf9\u5e94\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u8868
         * f.file->private_data\u5b58\u50a8\u7684\u662f\u6b64\u524depoll_create\u4e2d\u65b0\u589e\u7684eventpoll\u8282\u70b9
         * \u5728eventpoll\u4e2d\u5b58\u50a8\u6587\u4ef6\u63cf\u8ff0\u7b26\u4fe1\u606f\u7684\u7ea2\u9ed1\u6811\u4e2d\u67e5\u627e\u6307\u5b9a\u7684fd\u5bf9\u5e94\u7684epitem\u5b9e\u4f8b
         *\/
        f = fdget(epfd);

        if (op == EPOLL_CTL_ADD) {
            if (!list_empty(&f.file->f_ep_links) || is_file_epoll(tf.file)) {
    \t\t\tfull_check = 1;
                if (is_file_epoll(tf.file)) {
    \t\t\t\terror = -ELOOP;
    \t\t\t\tif (ep_loop_check(ep, tf.file) != 0) {
    \t\t\t\t\tclear_tfile_check_list();
    \t\t\t\t\tgoto error_tgt_fput;
    \t\t\t\t}
    \t\t\t} else
                 \/* \u5c06\u76ee\u6807\u6587\u4ef6\u6dfb\u52a0\u5230epoll\u5168\u5c40\u7684tfile_check_list\u4e2d *\/
    \t\t\tlist_add(&tf.file->f_tfile_llink, &tfile_check_list);
            }
    \t}

    \tepi = ep_find(ep, tf.file, fd);
    \tswitch (op) {
    \tcase EPOLL_CTL_ADD:\/* \u65b0\u589e\u8282\u70b9 *\/
    \t\tif (!epi)
    \t\t\terror = ep_insert(ep, &epds, tf.file, fd, full_check);
    \t\telse
    \t\t\terror = -EEXIST;
    \t\t\/* \u6e05\u7a7a\u6587\u4ef6\u68c0\u67e5\u5217\u8868 *\/
            if (full_check)
                clear_tfile_check_list();
    \t\tbreak;
    \tcase EPOLL_CTL_DEL:\/* \u5220\u9664\u8282\u70b9 *\/
            if (epi)
                error = ep_remove(ep, epi);
            else
                error = -ENOENT;
    \t\tbreak;
    \tcase EPOLL_CTL_MOD:\/* \u4fee\u6539\u8282\u70b9 *\/
            if (epi) {
                error = ep_modify(ep, epi, &epds);
            else
                error = -ENOENT;
    \t\tbreak;
    \t}

        fdput(tf);
    \tfdput(f);
    error_return:
    \treturn error;
    }<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    epoll_ctl<\/code>\u63a5\u53e3\u4e3b\u8981\u7528\u4e8e\u5bf9\u60f3\u8981\u76d1\u89c6\u7684file<\/code>\u505a\u589e\u5220\u6539\u7684\u64cd\u4f5c\uff0c\u5c06\u6570\u636e\u4ece\u7528\u6237\u7a7a\u95f4\u62f7\u8d1d\u81f3\u5185\u6838\u7a7a\u95f4<\/strong>\u7136\u540e\u6839\u636e\u4e0d\u540c\u7684\u64cd\u4f5c\u7c7b\u578b\u8c03\u7528\u4e0d\u540c\u7684\u63a5\u53e3<\/p>\n\n\n\n
    \u4f7f\u7528fdget<\/code>\u63a5\u53e3\u83b7\u53d6\u53e5\u67c4\u5bf9\u5e94\u7684\u8fdb\u7a0b\u63cf\u8ff0\u7b26task_struct<\/code>\uff0c\u7136\u540e\u901a\u8fc7task_struct<\/code>\u64cd\u4f5ceventpoll<\/code><\/p>\n\n\n\n
    \u76f8\u5173\u63a5\u53e3\u53ca\u8c03\u7528\u6808<\/strong><\/p>\n\n\n\n
    ep_insert
    \t->reverse_path_check
    \t\t\/* tfile_check_list\u94fe\u8868 *\/
    \t\t->list_for_each_entry

    \/* \u6b64\u5904remove\u63a5\u53e3\u64cd\u4f5c\u7684\u5176\u5b9e\u662f\u4e00\u4e2aeppoll_entry\u94fe\u8868 *\/
    ep_remove
        ->ep_unregister_pollwait
    \t\t->ep_remove_wait_queue

    ep_modify
        ->ep_pm_stay_awake<\/code><\/pre>\n\n\n\n
    7.4 \u7b49\u5f85epoll<\/code>\u4e8b\u4ef6<\/h3>\n\n\n\n
    epoll_wait<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u5bf9ep_poll<\/code>\u7684\u4e00\u5c42\u5c01\u88c5<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
                    int, maxevents, int, timeout)
    {
    \treturn do_epoll_wait(epfd, events, maxevents, timeout);
    }

    static int do_epoll_wait(int epfd, struct epoll_event __user *events,
                             int maxevents, int timeout)
    {
    \tint error;
    \tstruct fd f;
    \tstruct eventpoll *ep;

    \tf = fdget(epfd);

    \tep = f.file->private_data;
    \terror = ep_poll(ep, events, maxevents, timeout);

    \tfdput(f);
    \treturn error;
    }<\/code><\/pre>\n\n\n\n
    ep_poll<\/code>\u51fd\u6570<\/strong><\/p>\n\n\n\n
    \u8fd9\u4e2a\u51fd\u6570\u771f\u6b63\u5c06\u6267\u884cepoll_wait<\/code>\u7684\u8fdb\u7a0b\u5e26\u5165\u7761\u7720\u72b6\u6001<\/p>\n\n\n\n
    \u6838\u5fc3\u903b\u8f91\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    \n
    \u7b14\u8005\u6ce8\uff1a\u4e0b\u6587\u4ee3\u7801\u5df2\u683c\u5f0f\u5316\u5904\u7406\uff0c\u5e76\u9002\u5f53\u7b80\u5316\u53ea\u4fdd\u7559\u6838\u5fc3\u903b\u8f91<\/p>\n<\/blockquote>\n\n\n\n
    \n\/*\n * ep_poll - \u68c0\u7d22\u51c6\u5907\u597d\u7684\u4e8b\u4ef6\uff0c\u5e76\u5c06\u5b83\u4eec\u4f20\u9012\u5230\u8c03\u7528\u8005\u63d0\u4f9b\u7684\u4e8b\u4ef6\u7f13\u51b2\u533a\n *\n * @ep: \u6307\u5411eventpoll\u4e0a\u4e0b\u6587\u7684\u6307\u9488\n * @events: \u6307\u5411\u7528\u6237\u7a7a\u95f4\u7f13\u51b2\u533a\u7684\u6307\u9488\uff0c\u51c6\u5907\u597d\u7684\u4e8b\u4ef6\u5e94\u8be5\u5b58\u50a8\u5728\u8fd9\u91cc\n * @maxevents: \u8c03\u7528\u8005\u4e8b\u4ef6\u7f13\u51b2\u533a\u7684\u5927\u5c0f(\u4ee5\u4e8b\u4ef6\u6570\u91cf\u8868\u793a)\n * @timeout: \u51c6\u5907\u4e8b\u4ef6\u83b7\u53d6\u64cd\u4f5c\u7684\u6700\u5927\u8d85\u65f6\u65f6\u95f4\uff0c\u5355\u4f4d\u4e3a\u6beb\u79d2\u3002\u5982\u679c@timeout\u4e3a\u96f6\uff0c\u5219\u8be5\u51fd\u6570\u4e0d\u4f1a\u963b\u585e\n * \t\t\t \u800c\u5982\u679c@timeout\u5c0f\u4e8e\u96f6\uff0c\u5219\u8be5\u51fd\u6570\u5c06\u963b\u585e\uff0c\u76f4\u5230\u81f3\u5c11\u68c0\u7d22\u5230\u4e00\u4e2a\u4e8b\u4ef6(\u6216\u53d1\u751f\u9519\u8bef)\n *\/<\/code>\nstatic int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,\n                   int maxevents, long timeout)\n{\n\tint res = 0, eavail, timed_out = 0;\n\tu64 slack = 0;\n\tbool waiter = false;\n\twait_queue_entry_t wait;\n\tktime_t expires, *to = NULL;\n\n\tlockdep_assert_irqs_enabled();\n\n\t\/* timeout\u5927\u4e8e0\u65f6\uff0c\u83b7\u53d6\u9ad8\u7cbe\u5ea6\u5b9a\u65f6\u5668\u7684\u8bef\u5dee\u503c *\/\n\tif (timeout > 0) {\n\t\tslack = select_estimate_accuracy(&timeout);\n\t} else if (timeout == 0) {\n\t\t\/* timeout\u7b49\u4e8e0\u65f6\uff0c\u5c06timed_out\u7f6e\u4e3a1\u8df3\u8f6c\u540e\u4f1a\u76f4\u63a5\u8fdb\u5165\u7b49\u5f85\u6d41\u7a0b *\/\n\t\ttimed_out = 1;\n\t\teavail = ep_events_available(ep);\n\n\t\tgoto send_events;\n\t}\n\nfetch_events:\n\t\/* \u5982\u679c\u6ca1\u6709\u53ef\u7528\u4e8b\u4ef6\uff0c\u5c31\u8c03\u7528ep_busy_loop()\u51fd\u6570\u8fdb\u884c\u5fd9\u7b49\u5f85\uff0c\u76f4\u5230\u6709\u4e8b\u4ef6\u53d8\u4e3a\u53ef\u7528\u6216\u8005\u8d85\u65f6 *\/\n\tif (!ep_events_available(ep))\n\t\tep_busy_loop(ep, timed_out);\n\n\t\/* \u83b7\u53d6epoll\u5b9e\u4f8b\u4e2d\u5f53\u524d\u53ef\u7528\u4e8b\u4ef6\u6570 *\/\n\teavail = ep_events_available(ep);\n\tif (eavail)\n\t\tgoto send_events;\n\n\tep_reset_busy_poll_napi_id(ep);\n\n\t\/*\n\t * waiter\u8868\u793a\u5f53\u524d\u8fdb\u7a0b\u662f\u5426\u5b58\u5728\u4e8e\u7b49\u5f85\u961f\u5217\u4e2d\n\t * init_waitqueue_entry\u521d\u59cb\u5316\u4e00\u4e2a\u7b49\u5f85\u961f\u5217\uff0c\u5c06\u5f53\u524d\u961f\u5217\u548cwait\u5173\u8054\n\t * __add_wait_queue_exclusive\u5c06\u5f53\u524d\u8fdb\u7a0b\u6dfb\u52a0\u5230\u7b49\u5f85\u961f\u5217\u4e2d\n\t * \u4ee5\u4fbf\u5728\u4e8b\u4ef6\u4e0d\u53ef\u7528\u65f6\u8fdb\u5165\u7761\u7720\u72b6\u6001\uff0c\u7b49\u5f85\u4e8b\u4ef6\u7684\u53d1\u751f\n\t *\/\n\tif (!waiter) {\n\t\twaiter = true;\n\t\tinit_waitqueue_entry(&wait, current);\n\n\t\t__add_wait_queue_exclusive(&ep->wq, &wait);\n\t}\n\n\tfor (;;) {\n\t\tset_current_state(TASK_INTERRUPTIBLE);\n\n\t\t\/* \u82e5\u6b64\u65f6\u6709\u65b0\u7684\u53ef\u7528\u4e8b\u4ef6\u5219\u8df3\u51fa\u5faa\u73af *\/\n\t\teavail = ep_events_available(ep);\n\t\tif (eavail)\n\t\t\tbreak;\n\n\t\t\/* \u8bbe\u7f6e\u9ad8\u7cbe\u5ea6\u8d85\u65f6\u5b9a\u65f6\u5668\uff0c\u82e5\u8d85\u65f6\u5219\u8df3\u51fa\u5faa\u73af *\/\n\t\tif (!schedule_hrtimeout_range(timeout, slack, HRTIMER_MODE_ABS)) {\n\t\t\ttimed_out = 1;\n\t\t\tbreak;\n\t\t}\n\t}\n\n\tset_current_state(TASK_RUNNING);\n\nsend_events:\n\t\/*\n\t * Try to transfer events to user space. In case we get 0 events and\n\t * there's still timeout left over, we go trying again in search of\n\t * more luck.\n\t *\/\n\t\/* \u5f53 epoll \u5b9e\u4f8b\u4e2d\u6709\u53ef\u7528\u4e8b\u4ef6\u3001\u4e8b\u4ef6\u53d1\u9001\u6210\u529f\u3001\u4e14\u6ca1\u6709\u53d1\u751f\u8d85\u65f6\u91cd\u65b0\u6267\u884cfetch_events *\/\n\tif (eavail && !(res = ep_send_events(ep, events, maxevents)) && !timed_out)\n\t\tgoto fetch_events;\n\n\tif (waiter) {\n\t\t__remove_wait_queue(&ep->wq, &wait);\n\t}\n\n\treturn res;\n}<\/code><\/pre>\n\n\n\n
    \u6838\u5fc3\u601d\u60f3<\/strong><\/p>\n\n\n\n
    ep_poll<\/code>\u901a\u8fc7\u9ad8\u7cbe\u5ea6\u5b9a\u65f6\u5668\u548c\u8fdb\u7a0b\u5fd9\u7b49\u5f85\uff0c\u5728\u4e0d\u65ad\u5730\u5faa\u73af\u4e2d\u901a\u8fc7ep_events_available()<\/code>\u68c0\u6d4b\u53ef\u7528\u4e8b\u4ef6\u3002\u6700\u7ec8\u5c06\u53ef\u7528\u4e8b\u4ef6\u5b58\u50a8\u5728events<\/code>\u4e2d<\/p>\n\n\n\n
    \u5173\u952e\u63a5\u53e3\u51fd\u6570\u8c03\u7528\u6808<\/p>\n\n\n\n
    \/* \u6b64\u5904\u68c0\u67e5\u7684\u662f\u5c31\u7eea\u94fe\u8868\u7684\u5185\u5bb9 *\/
    ep_events_available(struct eventpoll *ep)
        ->list_empty_careful(&ep->rdllist)<\/code><\/pre>\n\n\n\n
    \u516b\u3001epoll<\/code>\u4e0eselect<\/code>\u3001poll<\/code>\u7684\u5bf9\u6bd4<\/h2>\n\n\n\n
    1) \u7528\u6237\u6001\u5c06\u6587\u4ef6\u63cf\u8ff0\u7b26\u4f20\u5165\u5185\u6838\u7684\u65b9\u5f0f<\/strong><\/p>\n\n\n\n
      \n
    • select<\/code>\uff1a\u521b\u5efa3\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u96c6\u5e76\u62f7\u8d1d\u5230\u5185\u6838\u4e2d\uff0c\u5206\u522b\u76d1\u542c\u8bfb\u3001\u5199\u3001\u5f02\u5e38\u52a8\u4f5c\u3002\u8fd9\u91cc\u53d7\u5230\u5355\u4e2a\u8fdb\u7a0b\u53ef\u4ee5\u6253\u5f00\u7684fd<\/code>\u6570\u91cf\u9650\u5236\uff0c\u9ed8\u8ba4\u662f1024<\/code>\u3002<\/li>\n\n\n\n
    • poll<\/code>\uff1a\u5c06\u4f20\u5165\u7684struct pollfd<\/code>\u7ed3\u6784\u4f53\u6570\u7ec4\u62f7\u8d1d\u5230\u5185\u6838\u4e2d\u8fdb\u884c\u76d1\u542c\u3002<\/li>\n\n\n\n
    • epoll<\/code>\uff1a\u6267\u884cepoll_create<\/code>\u4f1a\u5728\u5185\u6838\u7684\u9ad8\u901fcache<\/code>\u533a\u4e2d\u5efa\u7acb\u4e00\u9897\u7ea2\u9ed1\u6811\u4ee5\u53ca\u5c31\u7eea\u94fe\u8868(\u8be5\u94fe\u8868\u5b58\u50a8\u5df2\u7ecf\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26)\u3002\u63a5\u7740\u7528\u6237\u6267\u884c\u7684epoll_ctl<\/code>\u51fd\u6570\u6dfb\u52a0\u6587\u4ef6\u63cf\u8ff0\u7b26\u4f1a\u5728\u7ea2\u9ed1\u6811\u4e0a\u589e\u52a0\u76f8\u5e94\u7684\u7ed3\u70b9\u3002<\/li>\n<\/ul>\n\n\n\n
      2) \u5185\u6838\u6001\u68c0\u6d4b\u6587\u4ef6\u63cf\u8ff0\u7b26\u8bfb\u5199\u72b6\u6001\u7684\u65b9\u5f0f<\/strong><\/p>\n\n\n\n
        \n
      • select<\/code>\uff1a\u91c7\u7528\u8f6e\u8be2\u65b9\u5f0f\uff0c\u904d\u5386\u6240\u6709fd<\/code>\uff0c\u6700\u540e\u8fd4\u56de\u4e00\u4e2a\u63cf\u8ff0\u7b26\u8bfb\u5199\u64cd\u4f5c\u662f\u5426\u5c31\u7eea\u7684mask<\/code>\u63a9\u7801\uff0c\u6839\u636e\u8fd9\u4e2a\u63a9\u7801\u7ed9fd_set<\/code>\u8d4b\u503c\u3002<\/li>\n\n\n\n
      • poll<\/code>\uff1a\u540c\u6837\u91c7\u7528\u8f6e\u8be2\u65b9\u5f0f\uff0c\u67e5\u8be2\u6bcf\u4e2afd<\/code>\u7684\u72b6\u6001\uff0c\u5982\u679c\u5c31\u7eea\u5219\u5728\u7b49\u5f85\u961f\u5217\u4e2d\u52a0\u5165\u4e00\u9879\u5e76\u7ee7\u7eed\u904d\u5386\u3002<\/li>\n\n\n\n
      • epoll<\/code>\uff1a\u91c7\u7528\u56de\u8c03\u673a\u5236\u3002\u5728\u6267\u884cepoll_ctl<\/code>\u7684add<\/code>\u64cd\u4f5c\u65f6\uff0c\u4e0d\u4ec5\u5c06\u6587\u4ef6\u63cf\u8ff0\u7b26\u653e\u5230\u7ea2\u9ed1\u6811\u4e0a\uff0c\u800c\u4e14\u4e5f\u6ce8\u518c\u4e86\u56de\u8c03\u51fd\u6570\uff0c\u5185\u6838\u5728\u68c0\u6d4b\u5230\u67d0\u6587\u4ef6\u63cf\u8ff0\u7b26\u53ef\u8bfb\/\u53ef\u5199\u65f6\u4f1a\u8c03\u7528\u56de\u8c03\u51fd\u6570\uff0c\u8be5\u56de\u8c03\u51fd\u6570\u5c06\u6587\u4ef6\u63cf\u8ff0\u7b26\u653e\u5728\u5c31\u7eea\u94fe\u8868\u4e2d\u3002<\/li>\n<\/ul>\n\n\n\n
        3) \u627e\u5230\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u5e76\u4f20\u9012\u7ed9\u7528\u6237\u6001\u7684\u65b9\u5f0f<\/strong><\/p>\n\n\n\n
          \n
        • select<\/code>\uff1a\u5c06\u4e4b\u524d\u4f20\u5165\u7684fd_set<\/code>\u62f7\u8d1d\u4f20\u51fa\u5230\u7528\u6237\u6001\u5e76\u8fd4\u56de\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u603b\u6570\u3002\u7528\u6237\u6001\u5e76\u4e0d\u77e5\u9053\u662f\u54ea\u4e9b\u6587\u4ef6\u63cf\u8ff0\u7b26\u5904\u4e8e\u5c31\u7eea\u6001\uff0c\u9700\u8981\u904d\u5386\u6765\u5224\u65ad\u3002<\/li>\n\n\n\n
        • poll<\/code>\uff1a\u5c06\u4e4b\u524d\u4f20\u5165\u7684fd<\/code>\u6570\u7ec4\u62f7\u8d1d\u4f20\u51fa\u7528\u6237\u6001\u5e76\u8fd4\u56de\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u603b\u6570\u3002\u7528\u6237\u6001\u5e76\u4e0d\u77e5\u9053\u662f\u54ea\u4e9b\u6587\u4ef6\u63cf\u8ff0\u7b26\u5904\u4e8e\u5c31\u7eea\u6001\uff0c\u9700\u8981\u904d\u5386\u6765\u5224\u65ad\u3002<\/li>\n\n\n\n
        • epoll<\/code>\uff1aepoll_wait<\/code>\u53ea\u7528\u89c2\u5bdf\u5c31\u7eea\u94fe\u8868\u4e2d\u6709\u65e0\u6570\u636e\u5373\u53ef\uff0c\u6700\u540e\u5c06\u94fe\u8868\u7684\u6570\u636e\u8fd4\u56de\u7ed9\u6570\u7ec4\u5e76\u8fd4\u56de\u5c31\u7eea\u7684\u6570\u91cf\u3002\u5185\u6838\u5c06\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u653e\u5728\u4f20\u5165\u7684\u6570\u7ec4\u4e2d\uff0c\u6240\u4ee5\u53ea\u7528\u904d\u5386\u4f9d\u6b21\u5904\u7406\u5373\u53ef\u3002\u8fd9\u91cc\u8fd4\u56de\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u662f\u901a\u8fc7mmap<\/code>\u8ba9\u5185\u6838\u548c\u7528\u6237\u7a7a\u95f4\u5171\u4eab\u540c\u4e00\u5757\u5185\u5b58\u5b9e\u73b0\u4f20\u9012\u7684\uff0c\u51cf\u5c11\u4e86\u4e0d\u5fc5\u8981\u7684\u62f7\u8d1d\u3002<\/li>\n<\/ul>\n\n\n\n
          4) \u91cd\u590d\u76d1\u542c\u7684\u5904\u7406\u65b9\u5f0f<\/strong><\/p>\n\n\n\n
            \n
          • select<\/code>\uff1a\u5c06\u65b0\u7684\u76d1\u542c\u6587\u4ef6\u63cf\u8ff0\u7b26\u96c6\u5408\u62f7\u8d1d\u4f20\u5165\u5185\u6838\u4e2d\uff0c\u7ee7\u7eed\u4ee5\u4e0a\u6b65\u9aa4\u3002<\/li>\n\n\n\n
          • poll<\/code>\uff1a\u5c06\u65b0\u7684struct pollfd<\/code>\u7ed3\u6784\u4f53\u6570\u7ec4\u62f7\u8d1d\u4f20\u5165\u5185\u6838\u4e2d\uff0c\u7ee7\u7eed\u4ee5\u4e0a\u6b65\u9aa4\u3002<\/li>\n\n\n\n
          • epoll<\/code>\uff1a\u65e0\u9700\u91cd\u65b0\u6784\u5efa\u7ea2\u9ed1\u6811\uff0c\u76f4\u63a5\u6cbf\u7528\u5df2\u5b58\u5728\u7684\u5373\u53ef\u3002<\/li>\n<\/ul>\n\n\n\n
            \u4e5d\u3001\u603b\u7ed3<\/h2>\n\n\n\n
            epoll\u66f4\u9ad8\u6548\u7684\u539f\u56e0<\/strong><\/p>\n\n\n\n
            1\uff09select<\/code>\u548cpoll<\/code>\u7684\u52a8\u4f5c\u57fa\u672c\u4e00\u81f4\uff0c\u53ea\u662fpoll<\/code>\u91c7\u7528\u94fe\u8868\u6765\u8fdb\u884c\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u5b58\u50a8\uff0c\u800cselect<\/code>\u91c7\u7528fd\u6807\u6ce8\u4f4d\u6765\u5b58\u653e\uff0c\u6240\u4ee5select<\/code>\u4f1a\u53d7\u5230\u6700\u5927\u8fde\u63a5\u6570\u7684\u9650\u5236\uff0c\u800cpoll<\/code>\u4e0d\u4f1a\u3002<\/p>\n\n\n\n
            2\uff09select<\/code>\u3001poll<\/code>\u3001epoll<\/code>\u867d\u7136\u90fd\u4f1a\u8fd4\u56de\u5c31\u7eea\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u91cf\u3002\u4f46\u662fselect<\/code>\u548cpoll<\/code>\u5e76\u4e0d\u4f1a\u660e\u786e\u6307\u51fa\u662f\u54ea\u4e9b\u6587\u4ef6\u63cf\u8ff0\u7b26\u5c31\u7eea\uff0c\u800cepoll<\/code>\u4f1a\u3002\u9020\u6210\u7684\u533a\u522b\u5c31\u662f\uff0c\u7cfb\u7edf\u8c03\u7528\u8fd4\u56de\u540e\uff0c\u8c03\u7528select<\/code>\u548cpoll<\/code>\u7684\u7a0b\u5e8f\u9700\u8981\u904d\u5386\u76d1\u542c\u7684\u6574\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u627e\u5230\u662f\u8c01\u5904\u4e8e\u5c31\u7eea\uff0c\u800cepoll\u5219\u76f4\u63a5\u5904\u7406\u5373\u53ef\u3002<\/p>\n\n\n\n
            3\uff09select<\/code>\u3001poll<\/code>\u90fd\u9700\u8981\u5c06\u6709\u5173\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u6570\u636e\u7ed3\u6784\u62f7\u8d1d\u8fdb\u5185\u6838\uff0c\u6700\u540e\u518d\u62f7\u8d1d\u51fa\u6765\u3002\u800cepoll<\/code>\u521b\u5efa\u7684\u6709\u5173\u6587\u4ef6\u63cf\u8ff0\u7b26\u7684\u6570\u636e\u7ed3\u6784\u672c\u8eab\u5c31\u5b58\u4e8e\u5185\u6838\u6001\u4e2d\uff0c\u7cfb\u7edf\u8c03\u7528\u8fd4\u56de\u65f6\u5229\u7528mmap()<\/code>\u6587\u4ef6\u6620\u5c04\u5185\u5b58\u52a0\u901f\u4e0e\u5185\u6838\u7a7a\u95f4\u7684\u6d88\u606f\u4f20\u9012\uff1a\u5373epoll<\/code>\u4f7f\u7528mmap<\/code>\u51cf\u5c11\u590d\u5236\u5f00\u9500\u3002<\/p>\n\n\n\n
            4\uff09select<\/code>\u3001poll<\/code>\u91c7\u7528\u8f6e\u8be2\u7684\u65b9\u5f0f\u6765\u68c0\u67e5\u6587\u4ef6\u63cf\u8ff0\u7b26\u662f\u5426\u5904\u4e8e\u5c31\u7eea\u6001\uff0c\u800cepoll<\/code>\u91c7\u7528\u56de\u8c03\u673a\u5236\u3002\u9020\u6210\u7684\u7ed3\u679c\u5c31\u662f\uff0c\u968f\u7740fd<\/code>\u7684\u589e\u52a0\uff0cselect<\/code>\u548cpoll<\/code>\u7684\u6548\u7387\u4f1a\u7ebf\u6027\u964d\u4f4e\uff0c\u800cepoll<\/code>\u4e0d\u4f1a\u53d7\u5230\u592a\u5927\u5f71\u54cd\uff0c\u9664\u975e\u6d3b\u8dc3\u7684socket<\/code>\u5f88\u591a\u3002<\/p>\n\n\n\n
            5\uff09epoll<\/code>\u7684\u8fb9\u7f18\u89e6\u53d1\u6a21\u5f0f\u6548\u7387\u9ad8\uff0c\u7cfb\u7edf\u4e0d\u4f1a\u5145\u65a5\u5927\u91cf\u4e0d\u5173\u5fc3\u7684\u5c31\u7eea\u6587\u4ef6\u63cf\u8ff0\u7b26<\/p>\n\n\n\n
            \n
            \u867d\u7136epoll\u7684\u6027\u80fd\u6700\u597d\uff0c\u4f46\u662f\u5728\u8fde\u63a5\u6570\u5c11\u5e76\u4e14\u8fde\u63a5\u90fd\u5341\u5206\u6d3b\u8dc3\u7684\u60c5\u51b5\u4e0b\uff0cselect\u548cpoll\u7684\u6027\u80fd\u53ef\u80fd\u6bd4epoll\u597d\uff0c\u6bd5\u7adfepoll\u7684\u901a\u77e5\u673a\u5236\u9700\u8981\u5f88\u591a\u51fd\u6570\u56de\u8c03\u3002<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"
            \u53c2\u8003\u6587\u6863\uff1a \u3010Linux\u6df1\u5165\u3011epoll\u6e90\u7801\u5256\u6790_epoll\u5256\u6790-CSDN\u535a\u5ba2 epoll\u6e90\u7801\u6df1\u5ea6\u5256\u6790 &#8 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[6,1],"tags":[],"class_list":["post-19","post","type-post","status-publish","format-standard","hentry","category-linux-knowledge","category-source-code-analysis"],"_links":{"self":[{"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=\/wp\/v2\/posts\/19","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=19"}],"version-history":[{"count":11,"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=\/wp\/v2\/posts\/19\/revisions"}],"predecessor-version":[{"id":245,"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=\/wp\/v2\/posts\/19\/revisions\/245"}],"wp:attachment":[{"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.garfield-blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}