X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fpoll-loop.c;h=7e328bc24ce486b2243cdfce1929c5464f513b02;hb=refs%2Fheads%2Fmanual;hp=aff2c335c732b88a0afa9152422d038c25b06039;hpb=a14bc59fb8f27db193d74662dc9c5cb8237177ef;p=openvswitch diff --git a/lib/poll-loop.c b/lib/poll-loop.c index aff2c335..7e328bc2 100644 --- a/lib/poll-loop.c +++ b/lib/poll-loop.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009 Nicira Networks. + * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -18,53 +18,53 @@ #include "poll-loop.h" #include #include +#include #include #include #include -#include "backtrace.h" #include "coverage.h" #include "dynamic-string.h" +#include "fatal-signal.h" #include "list.h" +#include "socket-util.h" #include "timeval.h" - -#define THIS_MODULE VLM_poll_loop #include "vlog.h" +#undef poll_fd_wait +#undef poll_timer_wait +#undef poll_timer_wait_until +#undef poll_immediate_wake + +VLOG_DEFINE_THIS_MODULE(poll_loop); + +COVERAGE_DEFINE(poll_fd_wait); +COVERAGE_DEFINE(poll_zero_timeout); + /* An event that will wake the following call to poll_block(). */ struct poll_waiter { /* Set when the waiter is created. */ struct list node; /* Element in global waiters list. */ int fd; /* File descriptor. */ short int events; /* Events to wait for (POLLIN, POLLOUT). */ - poll_fd_func *function; /* Callback function, if any, or null. */ - void *aux; /* Argument to callback function. */ - struct backtrace *backtrace; /* Optionally, event that created waiter. */ + const char *where; /* Where the waiter was created. */ /* Set only when poll_block() is called. */ - struct pollfd *pollfd; /* Pointer to element of the pollfds array - (null if added from a callback). */ + struct pollfd *pollfd; /* Pointer to element of the pollfds array. */ }; /* All active poll waiters. */ static struct list waiters = LIST_INITIALIZER(&waiters); -/* Number of elements in the waiters list. */ -static size_t n_waiters; - -/* Max time to wait in next call to poll_block(), in milliseconds, or -1 to +/* Time at which to wake up the next call to poll_block(), in milliseconds as + * returned by time_msec(), LLONG_MIN to wake up immediately, or LLONG_MAX to * wait forever. */ -static int timeout = -1; - -/* Backtrace of 'timeout''s registration, if debugging is enabled. */ -static struct backtrace timeout_backtrace; +static long long int timeout_when = LLONG_MAX; -/* Callback currently running, to allow verifying that poll_cancel() is not - * being called on a running callback. */ -#ifndef NDEBUG -static struct poll_waiter *running_cb; -#endif +/* Location where waiter created. */ +static const char *timeout_where; -static struct poll_waiter *new_waiter(int fd, short int events); +static struct poll_waiter *new_waiter(int fd, short int events, + const char *where); /* Registers 'fd' as waiting for the specified 'events' (which should be POLLIN * or POLLOUT or POLLIN | POLLOUT). The following call to poll_block() will @@ -72,12 +72,15 @@ static struct poll_waiter *new_waiter(int fd, short int events); * * The event registration is one-shot: only the following call to poll_block() * is affected. The event will need to be re-registered after poll_block() is - * called if it is to persist. */ + * called if it is to persist. + * + * Ordinarily the 'where' argument is supplied automatically; see poll-loop.h + * for more information. */ struct poll_waiter * -poll_fd_wait(int fd, short int events) +poll_fd_wait(int fd, short int events, const char *where) { COVERAGE_INC(poll_fd_wait); - return new_waiter(fd, events); + return new_waiter(fd, events, where); } /* Causes the following call to poll_block() to block for no more than 'msec' @@ -86,74 +89,154 @@ poll_fd_wait(int fd, short int events) * * The timer registration is one-shot: only the following call to poll_block() * is affected. The timer will need to be re-registered after poll_block() is - * called if it is to persist. */ + * called if it is to persist. + * + * Ordinarily the 'where' argument is supplied automatically; see poll-loop.h + * for more information. */ void -poll_timer_wait(int msec) +poll_timer_wait(long long int msec, const char *where) { - if (timeout < 0 || msec < timeout) { - timeout = MAX(0, msec); - if (VLOG_IS_DBG_ENABLED()) { - backtrace_capture(&timeout_backtrace); - } + long long int now = time_msec(); + long long int when; + + if (msec <= 0) { + /* Wake up immediately. */ + when = LLONG_MIN; + } else if ((unsigned long long int) now + msec <= LLONG_MAX) { + /* Normal case. */ + when = now + msec; + } else { + /* now + msec would overflow. */ + when = LLONG_MAX; + } + + poll_timer_wait_until(when, where); +} + +/* Causes the following call to poll_block() to wake up when the current time, + * as returned by time_msec(), reaches 'when' or later. If 'when' is earlier + * than the current time, the following call to poll_block() will not block at + * all. + * + * The timer registration is one-shot: only the following call to poll_block() + * is affected. The timer will need to be re-registered after poll_block() is + * called if it is to persist. + * + * Ordinarily the 'where' argument is supplied automatically; see poll-loop.h + * for more information. */ +void +poll_timer_wait_until(long long int when, const char *where) +{ + if (when < timeout_when) { + timeout_when = when; + timeout_where = where; } } /* Causes the following call to poll_block() to wake up immediately, without - * blocking. */ + * blocking. + * + * Ordinarily the 'where' argument is supplied automatically; see poll-loop.h + * for more information. */ void -poll_immediate_wake(void) +poll_immediate_wake(const char *where) { - poll_timer_wait(0); + poll_timer_wait(0, where); } -static void PRINTF_FORMAT(2, 3) -log_wakeup(const struct backtrace *backtrace, const char *format, ...) +/* Logs, if appropriate, that the poll loop was awakened by an event + * registered at 'where' (typically a source file and line number). The other + * arguments have two possible interpretations: + * + * - If 'pollfd' is nonnull then it should be the "struct pollfd" that caused + * the wakeup. 'timeout' is ignored. + * + * - If 'pollfd' is NULL then 'timeout' is the number of milliseconds after + * which the poll loop woke up. + */ +static void +log_wakeup(const char *where, const struct pollfd *pollfd, int timeout) { - struct ds ds; - va_list args; + static struct vlog_rate_limit trace_rl = VLOG_RATE_LIMIT_INIT(1, 1); + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10); + enum vlog_level level; + int cpu_usage; + struct ds s; - ds_init(&ds); - va_start(args, format); - ds_put_format_valist(&ds, format, args); - va_end(args); + cpu_usage = get_cpu_usage(); + if (VLOG_IS_DBG_ENABLED()) { + level = VLL_DBG; + } else if (cpu_usage > 50 && !VLOG_DROP_WARN(&rl)) { + level = VLL_WARN; + } else { + return; + } - if (backtrace) { - int i; + ds_init(&s); + ds_put_cstr(&s, "wakeup due to "); + if (pollfd) { + char *description = describe_fd(pollfd->fd); + if (pollfd->revents & POLLIN) { + ds_put_cstr(&s, "[POLLIN]"); + } + if (pollfd->revents & POLLOUT) { + ds_put_cstr(&s, "[POLLOUT]"); + } + if (pollfd->revents & POLLERR) { + ds_put_cstr(&s, "[POLLERR]"); + } + if (pollfd->revents & POLLHUP) { + ds_put_cstr(&s, "[POLLHUP]"); + } + if (pollfd->revents & POLLNVAL) { + ds_put_cstr(&s, "[POLLNVAL]"); + } + ds_put_format(&s, " on fd %d (%s)", pollfd->fd, description); + free(description); + } else { + ds_put_format(&s, "%d-ms timeout", timeout); + } + if (where) { + ds_put_format(&s, " at %s", where); + } + if (cpu_usage >= 0) { + ds_put_format(&s, " (%d%% CPU usage)", cpu_usage); - ds_put_char(&ds, ':'); - for (i = 0; i < backtrace->n_frames; i++) { - ds_put_format(&ds, " 0x%x", backtrace->frames[i]); + if (!vlog_should_drop(THIS_MODULE, level, &trace_rl)) { + ds_put_char(&s, '\n'); + format_backtraces(&s, 2); } } - VLOG_DBG("%s", ds_cstr(&ds)); - ds_destroy(&ds); + VLOG(level, "%s", ds_cstr(&s)); + ds_destroy(&s); } /* Blocks until one or more of the events registered with poll_fd_wait() * occurs, or until the minimum duration registered with poll_timer_wait() - * elapses, or not at all if poll_immediate_wake() has been called. - * - * Also executes any autonomous subroutines registered with poll_fd_callback(), - * if their file descriptors have become ready. */ + * elapses, or not at all if poll_immediate_wake() has been called. */ void poll_block(void) { static struct pollfd *pollfds; static size_t max_pollfds; - struct poll_waiter *pw; - struct list *node; - int n_pollfds; + struct poll_waiter *pw, *next; + int n_waiters, n_pollfds; + int elapsed; int retval; - assert(!running_cb); + /* Register fatal signal events before actually doing any real work for + * poll_block. */ + fatal_signal_wait(); + + n_waiters = list_size(&waiters); if (max_pollfds < n_waiters) { max_pollfds = n_waiters; pollfds = xrealloc(pollfds, max_pollfds * sizeof *pollfds); } n_pollfds = 0; - LIST_FOR_EACH (pw, struct poll_waiter, node, &waiters) { + LIST_FOR_EACH (pw, node, &waiters) { pw->pollfd = &pollfds[n_pollfds]; pollfds[n_pollfds].fd = pw->fd; pollfds[n_pollfds].events = pw->events; @@ -161,107 +244,55 @@ poll_block(void) n_pollfds++; } - if (!timeout) { + if (timeout_when == LLONG_MIN) { COVERAGE_INC(poll_zero_timeout); } - retval = time_poll(pollfds, n_pollfds, timeout); + retval = time_poll(pollfds, n_pollfds, timeout_when, &elapsed); if (retval < 0) { static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); VLOG_ERR_RL(&rl, "poll: %s", strerror(-retval)); - } else if (!retval && VLOG_IS_DBG_ENABLED()) { - log_wakeup(&timeout_backtrace, "%d-ms timeout", timeout); + } else if (!retval) { + log_wakeup(timeout_where, NULL, elapsed); } - for (node = waiters.next; node != &waiters; ) { - pw = CONTAINER_OF(node, struct poll_waiter, node); - if (!pw->pollfd || !pw->pollfd->revents) { - if (pw->function) { - node = node->next; - continue; - } - } else { - if (VLOG_IS_DBG_ENABLED()) { - log_wakeup(pw->backtrace, "%s%s%s%s%s on fd %d", - pw->pollfd->revents & POLLIN ? "[POLLIN]" : "", - pw->pollfd->revents & POLLOUT ? "[POLLOUT]" : "", - pw->pollfd->revents & POLLERR ? "[POLLERR]" : "", - pw->pollfd->revents & POLLHUP ? "[POLLHUP]" : "", - pw->pollfd->revents & POLLNVAL ? "[POLLNVAL]" : "", - pw->fd); - } - - if (pw->function) { -#ifndef NDEBUG - running_cb = pw; -#endif - pw->function(pw->fd, pw->pollfd->revents, pw->aux); -#ifndef NDEBUG - running_cb = NULL; -#endif - } + LIST_FOR_EACH_SAFE (pw, next, node, &waiters) { + if (pw->pollfd->revents) { + log_wakeup(pw->where, pw->pollfd, 0); } - node = node->next; poll_cancel(pw); } - timeout = -1; - timeout_backtrace.n_frames = 0; -} + timeout_when = LLONG_MAX; + timeout_where = NULL; -/* Registers 'function' to be called with argument 'aux' by poll_block() when - * 'fd' becomes ready for one of the events in 'events', which should be POLLIN - * or POLLOUT or POLLIN | POLLOUT. - * - * The callback registration persists until the event actually occurs. At that - * point, it is automatically de-registered. The callback function must - * re-register the event by calling poll_fd_callback() again within the - * callback, if it wants to be called back again later. */ -struct poll_waiter * -poll_fd_callback(int fd, short int events, poll_fd_func *function, void *aux) -{ - struct poll_waiter *pw = new_waiter(fd, events); - pw->function = function; - pw->aux = aux; - return pw; + /* Handle any pending signals before doing anything else. */ + fatal_signal_run(); } -/* Cancels the file descriptor event registered with poll_fd_wait() or - * poll_fd_callback(). 'pw' must be the struct poll_waiter returned by one of - * those functions. +/* Cancels the file descriptor event registered with poll_fd_wait() using 'pw', + * the struct poll_waiter returned by that function. * * An event registered with poll_fd_wait() may be canceled from its time of * registration until the next call to poll_block(). At that point, the event - * is automatically canceled by the system and its poll_waiter is freed. - * - * An event registered with poll_fd_callback() may be canceled from its time of - * registration until its callback is actually called. At that point, the - * event is automatically canceled by the system and its poll_waiter is - * freed. */ + * is automatically canceled by the system and its poll_waiter is freed. */ void poll_cancel(struct poll_waiter *pw) { if (pw) { - assert(pw != running_cb); list_remove(&pw->node); - free(pw->backtrace); free(pw); - n_waiters--; } } /* Creates and returns a new poll_waiter for 'fd' and 'events'. */ static struct poll_waiter * -new_waiter(int fd, short int events) +new_waiter(int fd, short int events, const char *where) { - struct poll_waiter *waiter = xcalloc(1, sizeof *waiter); + struct poll_waiter *waiter = xzalloc(sizeof *waiter); assert(fd >= 0); waiter->fd = fd; waiter->events = events; - if (VLOG_IS_DBG_ENABLED()) { - waiter->backtrace = xmalloc(sizeof *waiter->backtrace); - backtrace_capture(waiter->backtrace); - } + waiter->where = where; list_push_back(&waiters, &waiter->node); - n_waiters++; return waiter; }