From 2c06a96604516d28511fe74ebd9bf1a809834222 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Wed, 10 Jul 2013 10:54:41 -0700 Subject: [PATCH] poll-loop: Make poll loop data structures per-thread. Signed-off-by: Ben Pfaff --- lib/poll-loop.c | 108 ++++++++++++++++++++++++++++++------------------ lib/poll-loop.h | 14 +++++-- 2 files changed, 78 insertions(+), 44 deletions(-) diff --git a/lib/poll-loop.c b/lib/poll-loop.c index 6200507bc..97fc8068c 100644 --- a/lib/poll-loop.c +++ b/lib/poll-loop.c @@ -25,6 +25,7 @@ #include "dynamic-string.h" #include "fatal-signal.h" #include "list.h" +#include "ovs-thread.h" #include "socket-util.h" #include "timeval.h" #include "vlog.h" @@ -39,25 +40,20 @@ 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 { - const char *where; /* Where the waiter was created. */ -}; - -/* All active poll waiters. */ -static struct poll_waiter *waiters; -static struct pollfd *pollfds; -static size_t n_waiters, allocated_waiters; +struct poll_loop { + /* All active poll waiters. */ + struct pollfd *pollfds; /* Events to pass to poll(). */ + const char **where; /* Where each pollfd was created. */ + size_t n_waiters; /* Number of elems in 'where' and 'pollfds'. */ + size_t allocated_waiters; /* Allocated elems in 'where' and 'pollfds'. */ -/* 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 long long int timeout_when = LLONG_MAX; - -/* Location where waiter created. */ -static const char *timeout_where; + /* Time at which to wake up the next call to poll_block(), LLONG_MIN to + * wake up immediately, or LLONG_MAX to wait forever. */ + long long int timeout_when; /* In msecs as returned by time_msec(). */ + const char *timeout_where; /* Where 'timeout_when' was set. */ +}; -static void new_waiter(int fd, short int events, const char *where); +static struct poll_loop *poll_loop(void); /* Registers 'fd' as waiting for the specified 'events' (which should be POLLIN * or POLLOUT or POLLIN | POLLOUT). The following call to poll_block() will @@ -72,8 +68,21 @@ static void new_waiter(int fd, short int events, const char *where); void poll_fd_wait(int fd, short int events, const char *where) { + struct poll_loop *loop = poll_loop(); + COVERAGE_INC(poll_fd_wait); - new_waiter(fd, events, where); + if (loop->n_waiters >= loop->allocated_waiters) { + loop->where = x2nrealloc(loop->where, &loop->allocated_waiters, + sizeof *loop->where); + loop->pollfds = xrealloc(loop->pollfds, + (loop->allocated_waiters + * sizeof *loop->pollfds)); + } + + loop->where[loop->n_waiters] = where; + loop->pollfds[loop->n_waiters].fd = fd; + loop->pollfds[loop->n_waiters].events = events; + loop->n_waiters++; } /* Causes the following call to poll_block() to block for no more than 'msec' @@ -120,9 +129,10 @@ poll_timer_wait(long long int msec, const char *where) void poll_timer_wait_until(long long int when, const char *where) { - if (when < timeout_when) { - timeout_when = when; - timeout_where = where; + struct poll_loop *loop = poll_loop(); + if (when < loop->timeout_when) { + loop->timeout_when = when; + loop->timeout_where = where; } } @@ -204,6 +214,7 @@ log_wakeup(const char *where, const struct pollfd *pollfd, int timeout) void poll_block(void) { + struct poll_loop *loop = poll_loop(); int elapsed; int retval; @@ -211,45 +222,62 @@ poll_block(void) * poll_block. */ fatal_signal_wait(); - if (timeout_when == LLONG_MIN) { + if (loop->timeout_when == LLONG_MIN) { COVERAGE_INC(poll_zero_timeout); } - retval = time_poll(pollfds, n_waiters, timeout_when, &elapsed); + + retval = time_poll(loop->pollfds, loop->n_waiters, + loop->timeout_when, &elapsed); if (retval < 0) { static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); VLOG_ERR_RL(&rl, "poll: %s", ovs_strerror(-retval)); } else if (!retval) { - log_wakeup(timeout_where, NULL, elapsed); + log_wakeup(loop->timeout_where, NULL, elapsed); } else if (get_cpu_usage() > 50 || VLOG_IS_DBG_ENABLED()) { size_t i; - for (i = 0; i < n_waiters; i++) { - if (pollfds[i].revents) { - log_wakeup(waiters[i].where, &pollfds[i], 0); + for (i = 0; i < loop->n_waiters; i++) { + if (loop->pollfds[i].revents) { + log_wakeup(loop->where[i], &loop->pollfds[i], 0); } } } - timeout_when = LLONG_MAX; - timeout_where = NULL; - n_waiters = 0; + loop->timeout_when = LLONG_MAX; + loop->timeout_where = NULL; + loop->n_waiters = 0; /* Handle any pending signals before doing anything else. */ fatal_signal_run(); } -/* Creates a new poll_waiter for 'fd' and 'events', recording 'where' as the - * location where the event was registered. */ static void -new_waiter(int fd, short int events, const char *where) +free_poll_loop(void *loop_) { - if (n_waiters >= allocated_waiters) { - waiters = x2nrealloc(waiters, &allocated_waiters, sizeof *waiters); - pollfds = xrealloc(pollfds, allocated_waiters * sizeof *pollfds); + struct poll_loop *loop = loop_; + + free(loop->pollfds); + free(loop->where); + free(loop); +} + +static struct poll_loop * +poll_loop(void) +{ + static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER; + static pthread_key_t key; + struct poll_loop *loop; + + if (ovsthread_once_start(&once)) { + xpthread_key_create(&key, free_poll_loop); + ovsthread_once_done(&once); } - waiters[n_waiters].where = where; - pollfds[n_waiters].fd = fd; - pollfds[n_waiters].events = events; - n_waiters++; + loop = pthread_getspecific(key); + if (!loop) { + loop = xzalloc(sizeof *loop); + pthread_setspecific(key, loop); + } + return loop; } + diff --git a/lib/poll-loop.h b/lib/poll-loop.h index 6c78bbd69..6614ebe58 100644 --- a/lib/poll-loop.h +++ b/lib/poll-loop.h @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, 2010, 2011 Nicira, Inc. + * Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -16,14 +16,20 @@ /* High-level wrapper around the "poll" system call. * - * Intended usage is for the program's main loop to go about its business + * The intended usage is for each thread's main loop to go about its business * servicing whatever events it needs to. Then, when it runs out of immediate * tasks, it calls each subordinate module's "wait" function, which in turn * calls one (or more) of the functions poll_fd_wait(), poll_immediate_wake(), * and poll_timer_wait() to register to be awakened when the appropriate event * occurs. Then the main loop calls poll_block(), which blocks until one of - * the registered events happens. */ - + * the registered events happens. + * + * + * Thread-safety + * ============= + * + * The poll set is per-thread, so all functions in this module are thread-safe. + */ #ifndef POLL_LOOP_H #define POLL_LOOP_H 1 -- 2.20.1