/*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include "coverage.h"
#include "fatal-signal.h"
#include "util.h"
-
#include "vlog.h"
-#define THIS_MODULE VLM_timeval
-/* Initialized? */
-static bool inited;
+VLOG_DEFINE_THIS_MODULE(timeval)
+
+/* The clock to use for measuring time intervals. This is CLOCK_MONOTONIC by
+ * preference, but on systems that don't have a monotonic clock we fall back
+ * to CLOCK_REALTIME. */
+static clockid_t monotonic_clock;
-/* Has a timer tick occurred? */
-static volatile sig_atomic_t tick;
+/* Has a timer tick occurred?
+ *
+ * We initialize these to true to force time_init() to get called on the first
+ * call to time_msec() or another function that queries the current time. */
+static volatile sig_atomic_t wall_tick = true;
+static volatile sig_atomic_t monotonic_tick = true;
/* The current time, as of the last refresh. */
-static struct timeval now;
+static struct timespec wall_time;
+static struct timespec monotonic_time;
/* Time at which to die with SIGALRM (if not TIME_MIN). */
static time_t deadline = TIME_MIN;
+static void set_up_timer(void);
+static void set_up_signal(int flags);
static void sigalrm_handler(int);
-static void refresh_if_ticked(void);
+static void refresh_wall_if_ticked(void);
+static void refresh_monotonic_if_ticked(void);
static time_t time_add(time_t, time_t);
static void block_sigalrm(sigset_t *);
static void unblock_sigalrm(const sigset_t *);
static void log_poll_interval(long long int last_wakeup,
const struct rusage *last_rusage);
-static long long int timeval_to_msec(const struct timeval *);
-/* Initializes the timetracking module. */
-void
+/* Initializes the timetracking module.
+ *
+ * It is not necessary to call this function directly, because other time
+ * functions will call it automatically, but it doesn't hurt. */
+static void
time_init(void)
{
- struct sigaction sa;
- struct itimerval itimer;
-
+ static bool inited;
if (inited) {
return;
}
+ inited = true;
coverage_init();
- inited = true;
- gettimeofday(&now, NULL);
- tick = false;
+ if (!clock_gettime(CLOCK_MONOTONIC, &monotonic_time)) {
+ monotonic_clock = CLOCK_MONOTONIC;
+ } else {
+ monotonic_clock = CLOCK_REALTIME;
+ VLOG_DBG("monotonic timer not available");
+ }
+
+ set_up_signal(SA_RESTART);
+ set_up_timer();
+}
+
+static void
+set_up_signal(int flags)
+{
+ struct sigaction sa;
- /* Set up signal handler. */
memset(&sa, 0, sizeof sa);
sa.sa_handler = sigalrm_handler;
sigemptyset(&sa.sa_mask);
- sa.sa_flags = SA_RESTART;
+ sa.sa_flags = flags;
if (sigaction(SIGALRM, &sa, NULL)) {
ovs_fatal(errno, "sigaction(SIGALRM) failed");
}
+}
+
+/* Remove SA_RESTART from the flags for SIGALRM, so that any system call that
+ * is interrupted by the periodic timer interrupt will return EINTR instead of
+ * continuing after the signal handler returns.
+ *
+ * time_disable_restart() and time_enable_restart() may be usefully wrapped
+ * around function calls that might otherwise block forever unless interrupted
+ * by a signal, e.g.:
+ *
+ * time_disable_restart();
+ * fcntl(fd, F_SETLKW, &lock);
+ * time_enable_restart();
+ */
+void
+time_disable_restart(void)
+{
+ time_init();
+ set_up_signal(0);
+}
+
+/* Add SA_RESTART to the flags for SIGALRM, so that any system call that
+ * is interrupted by the periodic timer interrupt will continue after the
+ * signal handler returns instead of returning EINTR. */
+void
+time_enable_restart(void)
+{
+ time_init();
+ set_up_signal(SA_RESTART);
+}
+
+static void
+set_up_timer(void)
+{
+ static timer_t timer_id; /* "static" to avoid apparent memory leak. */
+ struct itimerspec itimer;
+
+ if (timer_create(monotonic_clock, NULL, &timer_id)) {
+ ovs_fatal(errno, "timer_create failed");
+ }
- /* Set up periodic timer. */
itimer.it_interval.tv_sec = 0;
- itimer.it_interval.tv_usec = TIME_UPDATE_INTERVAL * 1000;
+ itimer.it_interval.tv_nsec = TIME_UPDATE_INTERVAL * 1000 * 1000;
itimer.it_value = itimer.it_interval;
- if (setitimer(ITIMER_REAL, &itimer, NULL)) {
- ovs_fatal(errno, "setitimer failed");
+
+ if (timer_settime(timer_id, 0, &itimer, NULL)) {
+ ovs_fatal(errno, "timer_settime failed");
+ }
+}
+
+/* Set up the interval timer, to ensure that time advances even without calling
+ * time_refresh().
+ *
+ * A child created with fork() does not inherit the parent's interval timer, so
+ * this function needs to be called from the child after fork(). */
+void
+time_postfork(void)
+{
+ time_init();
+ set_up_timer();
+}
+
+static void
+refresh_wall(void)
+{
+ time_init();
+ clock_gettime(CLOCK_REALTIME, &wall_time);
+ wall_tick = false;
+}
+
+static void
+refresh_monotonic(void)
+{
+ time_init();
+
+ if (monotonic_clock == CLOCK_MONOTONIC) {
+ clock_gettime(monotonic_clock, &monotonic_time);
+ } else {
+ refresh_wall_if_ticked();
+ monotonic_time = wall_time;
}
+
+ monotonic_tick = false;
}
/* Forces a refresh of the current time from the kernel. It is not usually
void
time_refresh(void)
{
- gettimeofday(&now, NULL);
- tick = false;
+ wall_tick = monotonic_tick = true;
}
-/* Returns the current time, in seconds. */
+/* Returns a monotonic timer, in seconds. */
time_t
time_now(void)
{
- refresh_if_ticked();
- return now.tv_sec;
+ refresh_monotonic_if_ticked();
+ return monotonic_time.tv_sec;
}
-/* Returns the current time, in ms (within TIME_UPDATE_INTERVAL ms). */
+/* Same as time_now() except does not write to static variables, for use in
+ * signal handlers. */
+static time_t
+time_now_sig(void)
+{
+ struct timespec cur_time;
+
+ clock_gettime(monotonic_clock, &cur_time);
+ return cur_time.tv_sec;
+}
+
+/* Returns the current time, in seconds. */
+time_t
+time_wall(void)
+{
+ refresh_wall_if_ticked();
+ return wall_time.tv_sec;
+}
+
+/* Returns a monotonic timer, in ms (within TIME_UPDATE_INTERVAL ms). */
long long int
time_msec(void)
{
- refresh_if_ticked();
- return timeval_to_msec(&now);
+ refresh_monotonic_if_ticked();
+ return timespec_to_msec(&monotonic_time);
+}
+
+/* Returns the current time, in ms (within TIME_UPDATE_INTERVAL ms). */
+long long int
+time_wall_msec(void)
+{
+ refresh_wall_if_ticked();
+ return timespec_to_msec(&wall_time);
+}
+
+/* Stores a monotonic timer, accurate within TIME_UPDATE_INTERVAL ms, into
+ * '*ts'. */
+void
+time_timespec(struct timespec *ts)
+{
+ refresh_monotonic_if_ticked();
+ *ts = monotonic_time;
}
/* Stores the current time, accurate within TIME_UPDATE_INTERVAL ms, into
- * '*tv'. */
+ * '*ts'. */
void
-time_timeval(struct timeval *tv)
+time_wall_timespec(struct timespec *ts)
{
- refresh_if_ticked();
- *tv = now;
+ refresh_wall_if_ticked();
+ *ts = wall_time;
}
/* Configures the program to die with SIGALRM 'secs' seconds from now, if
static void
sigalrm_handler(int sig_nr)
{
- tick = true;
- if (deadline != TIME_MIN && time(0) > deadline) {
+ wall_tick = true;
+ monotonic_tick = true;
+ if (deadline != TIME_MIN && time_now_sig() > deadline) {
fatal_signal_handler(sig_nr);
}
}
static void
-refresh_if_ticked(void)
+refresh_wall_if_ticked(void)
{
- assert(inited);
- if (tick) {
- time_refresh();
+ if (wall_tick) {
+ refresh_wall();
+ }
+}
+
+static void
+refresh_monotonic_if_ticked(void)
+{
+ if (monotonic_tick) {
+ refresh_monotonic();
}
}
}
}
-static long long int
+long long int
+timespec_to_msec(const struct timespec *ts)
+{
+ return (long long int) ts->tv_sec * 1000 + ts->tv_nsec / (1000 * 1000);
+}
+
+long long int
timeval_to_msec(const struct timeval *tv)
{
return (long long int) tv->tv_sec * 1000 + tv->tv_usec / 1000;
struct rusage rusage;
getrusage(RUSAGE_SELF, &rusage);
- VLOG_WARN("%u ms poll interval (%lld ms user, %lld ms system) "
+ VLOG_WARN("%lld ms poll interval (%lld ms user, %lld ms system) "
"is over %u times the weighted mean interval %u ms "
"(%u samples)",
- (interval + 8) / 16,
+ now - last_wakeup,
timeval_diff_msec(&rusage.ru_utime, &last_rusage->ru_utime),
timeval_diff_msec(&rusage.ru_stime, &last_rusage->ru_stime),
interval / mean_interval,
rusage.ru_nvcsw - last_rusage->ru_nvcsw,
rusage.ru_nivcsw - last_rusage->ru_nivcsw);
}
- coverage_log(VLL_WARN, true);
+
+ /* Care should be taken in the value chosen for logging. Depending
+ * on the configuration, syslog can write changes synchronously,
+ * which can cause the coverage messages to take longer to log
+ * than the processing delay that triggered it. */
+ coverage_log(VLL_INFO, true);
}
/* Update exponentially weighted moving average. With these parameters, a
git://git.onelab.eu / sliver-openvswitch.git / blobdiff