/*
- * Copyright (c) 2008, 2009, 2010, 2011 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.
#include "timeval.h"
#include <assert.h>
#include <errno.h>
+#if HAVE_EXECINFO_H
+#include <execinfo.h>
+#endif
#include <poll.h>
#include <signal.h>
+#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#include "coverage.h"
+#include "dummy.h"
+#include "dynamic-string.h"
#include "fatal-signal.h"
#include "signals.h"
+#include "unixctl.h"
#include "util.h"
#include "vlog.h"
+#ifndef HAVE_EXECINFO_H
+#define HAVE_EXECINFO_H 0
+#endif
+
VLOG_DEFINE_THIS_MODULE(timeval);
/* The clock to use for measuring time intervals. This is CLOCK_MONOTONIC by
* to CLOCK_REALTIME. */
static clockid_t monotonic_clock;
-/* Has a timer tick occurred?
+/* Has a timer tick occurred? Only relevant if CACHE_TIME is true.
*
* 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 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;
+/* The monotonic time at which the time module was initialized. */
+static long long int boot_time;
+
+/* features for use by unit tests. */
+static struct timespec warp_offset; /* Offset added to monotonic_time. */
+static bool time_stopped; /* Disables real-time updates, if true. */
+
+/* Time in milliseconds at which to die with SIGALRM (if not LLONG_MAX). */
+static long long int deadline = LLONG_MAX;
+
+struct trace {
+ void *backtrace[32]; /* Populated by backtrace(). */
+ size_t n_frames; /* Number of frames in 'backtrace'. */
+};
+
+#define MAX_TRACES 50
+static struct trace traces[MAX_TRACES];
+static size_t trace_head = 0;
static void set_up_timer(void);
static void set_up_signal(int flags);
static void sigalrm_handler(int);
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);
static struct rusage *get_recent_rusage(void);
static void refresh_rusage(void);
+static void timespec_add(struct timespec *sum,
+ const struct timespec *a, const struct timespec *b);
+static unixctl_cb_func backtrace_cb;
-/* 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. */
+/* Initializes the timetracking module, if not already initialized. */
static void
time_init(void)
{
static bool inited;
+
if (inited) {
return;
}
inited = true;
+ memset(traces, 0, sizeof traces);
+
+ if (HAVE_EXECINFO_H && CACHE_TIME) {
+ unixctl_command_register("backtrace", "", 0, 0, backtrace_cb, NULL);
+ }
+
coverage_init();
if (!clock_gettime(CLOCK_MONOTONIC, &monotonic_time)) {
set_up_signal(SA_RESTART);
set_up_timer();
+
+ boot_time = time_msec();
}
static void
static timer_t timer_id; /* "static" to avoid apparent memory leak. */
struct itimerspec itimer;
+ if (!CACHE_TIME) {
+ return;
+ }
+
if (timer_create(monotonic_clock, NULL, &timer_id)) {
VLOG_FATAL("timer_create failed (%s)", strerror(errno));
}
{
time_init();
- if (monotonic_clock == CLOCK_MONOTONIC) {
- clock_gettime(monotonic_clock, &monotonic_time);
- } else {
- refresh_wall_if_ticked();
- monotonic_time = wall_time;
- }
+ if (!time_stopped) {
+ if (monotonic_clock == CLOCK_MONOTONIC) {
+ clock_gettime(monotonic_clock, &monotonic_time);
+ } else {
+ refresh_wall_if_ticked();
+ monotonic_time = wall_time;
+ }
+ timespec_add(&monotonic_time, &monotonic_time, &warp_offset);
- monotonic_tick = false;
+ monotonic_tick = false;
+ }
}
/* Forces a refresh of the current time from the kernel. It is not usually
* necessary to call this function, since the time will be refreshed
- * automatically at least every TIME_UPDATE_INTERVAL milliseconds. */
+ * automatically at least every TIME_UPDATE_INTERVAL milliseconds. If
+ * CACHE_TIME is false, we will always refresh the current time so this
+ * function has no effect. */
void
time_refresh(void)
{
return monotonic_time.tv_sec;
}
-/* 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)
void
time_alarm(unsigned int secs)
{
+ long long int now;
+ long long int msecs;
+
sigset_t oldsigs;
time_init();
+ time_refresh();
+
+ now = time_msec();
+ msecs = secs * 1000;
+
block_sigalrm(&oldsigs);
- deadline = secs ? time_add(time_now(), secs) : TIME_MIN;
+ deadline = now < LLONG_MAX - msecs ? now + msecs : LLONG_MAX;
unblock_sigalrm(&oldsigs);
}
time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when,
int *elapsed)
{
- static long long int last_wakeup;
+ static long long int last_wakeup = 0;
long long int start;
sigset_t oldsigs;
bool blocked;
int retval;
time_refresh();
- log_poll_interval(last_wakeup);
+ if (last_wakeup) {
+ log_poll_interval(last_wakeup);
+ }
coverage_clear();
start = time_msec();
blocked = false;
+
+ timeout_when = MIN(timeout_when, deadline);
+
for (;;) {
long long int now = time_msec();
int time_left;
if (retval < 0) {
retval = -errno;
}
+
time_refresh();
+ if (deadline <= time_msec()) {
+ fatal_signal_handler(SIGALRM);
+ if (retval < 0) {
+ retval = 0;
+ }
+ break;
+ }
+
if (retval != -EINTR) {
break;
}
- if (!blocked && deadline == TIME_MIN) {
+ if (!blocked && CACHE_TIME) {
block_sigalrm(&oldsigs);
blocked = true;
}
return retval;
}
-/* Returns the sum of 'a' and 'b', with saturation on overflow or underflow. */
-static time_t
-time_add(time_t a, time_t b)
-{
- return (a >= 0
- ? (b > TIME_MAX - a ? TIME_MAX : a + b)
- : (b < TIME_MIN - a ? TIME_MIN : a + b));
-}
-
static void
-sigalrm_handler(int sig_nr)
+sigalrm_handler(int sig_nr OVS_UNUSED)
{
wall_tick = true;
monotonic_tick = true;
- if (deadline != TIME_MIN && time_now_sig() > deadline) {
- fatal_signal_handler(sig_nr);
+
+#if HAVE_EXECINFO_H
+ if (CACHE_TIME) {
+ struct trace *trace = &traces[trace_head];
+
+ trace->n_frames = backtrace(trace->backtrace,
+ ARRAY_SIZE(trace->backtrace));
+ trace_head = (trace_head + 1) % MAX_TRACES;
}
+#endif
}
static void
refresh_wall_if_ticked(void)
{
- if (wall_tick) {
+ if (!CACHE_TIME || wall_tick) {
refresh_wall();
}
}
static void
refresh_monotonic_if_ticked(void)
{
- if (monotonic_tick) {
+ if (!CACHE_TIME || monotonic_tick) {
refresh_monotonic();
}
}
return (long long int) tv->tv_sec * 1000 + tv->tv_usec / 1000;
}
+/* Returns the monotonic time at which the "time" module was initialized, in
+ * milliseconds(). */
+long long int
+time_boot_msec(void)
+{
+ time_init();
+ return boot_time;
+}
+
void
xgettimeofday(struct timeval *tv)
{
}
static void
-log_poll_interval(long long int last_wakeup)
+timespec_add(struct timespec *sum,
+ const struct timespec *a,
+ const struct timespec *b)
{
- static unsigned int mean_interval; /* In 16ths of a millisecond. */
- static unsigned int n_samples;
+ struct timespec tmp;
- long long int now;
- unsigned int interval; /* In 16ths of a millisecond. */
+ tmp.tv_sec = a->tv_sec + b->tv_sec;
+ tmp.tv_nsec = a->tv_nsec + b->tv_nsec;
+ if (tmp.tv_nsec >= 1000 * 1000 * 1000) {
+ tmp.tv_nsec -= 1000 * 1000 * 1000;
+ tmp.tv_sec++;
+ }
- /* Compute interval from last wakeup to now in 16ths of a millisecond,
- * capped at 10 seconds (16000 in this unit). */
- now = time_msec();
- interval = MIN(10000, now - last_wakeup) << 4;
+ *sum = tmp;
+}
+
+static void
+log_poll_interval(long long int last_wakeup)
+{
+ long long int interval = time_msec() - last_wakeup;
- /* Warn if we took too much time between polls: at least 50 ms and at least
- * 8X the mean interval. */
- if (n_samples > 10 && interval > mean_interval * 8 && interval > 50 * 16) {
+ if (interval >= 1000) {
const struct rusage *last_rusage = get_recent_rusage();
struct rusage rusage;
getrusage(RUSAGE_SELF, &rusage);
- VLOG_WARN("%lld ms poll interval (%lld ms user, %lld ms system) "
- "is over %u times the weighted mean interval %u ms "
- "(%u samples)",
- 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,
- (mean_interval + 8) / 16, n_samples);
+ VLOG_WARN("Unreasonably long %lldms poll interval"
+ " (%lldms user, %lldms system)",
+ interval,
+ timeval_diff_msec(&rusage.ru_utime,
+ &last_rusage->ru_utime),
+ timeval_diff_msec(&rusage.ru_stime,
+ &last_rusage->ru_stime));
if (rusage.ru_minflt > last_rusage->ru_minflt
|| rusage.ru_majflt > last_rusage->ru_majflt) {
VLOG_WARN("faults: %ld minor, %ld major",
rusage.ru_nvcsw - last_rusage->ru_nvcsw,
rusage.ru_nivcsw - last_rusage->ru_nivcsw);
}
-
- /* 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
- * given value decays to 1% of its value in about 100 time steps. */
- if (n_samples++) {
- mean_interval = (mean_interval * 122 + interval * 6 + 64) / 128;
- } else {
- mean_interval = interval;
+ coverage_log();
}
}
\f
{
return cpu_usage;
}
+
+static void
+format_backtraces(struct ds *ds)
+{
+ time_init();
+
+#if HAVE_EXECINFO_H
+ if (CACHE_TIME) {
+ sigset_t oldsigs;
+ size_t i;
+
+ block_sigalrm(&oldsigs);
+
+ for (i = 0; i < MAX_TRACES; i++) {
+ struct trace *trace = &traces[i];
+ char **frame_strs;
+ size_t j;
+
+ if (!trace->n_frames) {
+ continue;
+ }
+
+ frame_strs = backtrace_symbols(trace->backtrace, trace->n_frames);
+
+ ds_put_format(ds, "Backtrace %zu\n", i + 1);
+ for (j = 0; j < trace->n_frames; j++) {
+ ds_put_format(ds, "%s\n", frame_strs[j]);
+ }
+ ds_put_cstr(ds, "\n");
+
+ free(frame_strs);
+ }
+ ds_chomp(ds, '\n');
+ unblock_sigalrm(&oldsigs);
+ }
+#endif
+}
+\f
+/* Unixctl interface. */
+
+/* "time/stop" stops the monotonic time returned by e.g. time_msec() from
+ * advancing, except due to later calls to "time/warp". */
+static void
+timeval_stop_cb(struct unixctl_conn *conn,
+ int argc OVS_UNUSED, const char *argv[] OVS_UNUSED,
+ void *aux OVS_UNUSED)
+{
+ time_stopped = true;
+ unixctl_command_reply(conn, NULL);
+}
+
+/* "time/warp MSECS" advances the current monotonic time by the specified
+ * number of milliseconds. Unless "time/stop" has also been executed, the
+ * monotonic clock continues to tick forward at the normal rate afterward.
+ *
+ * Does not affect wall clock readings. */
+static void
+timeval_warp_cb(struct unixctl_conn *conn,
+ int argc OVS_UNUSED, const char *argv[], void *aux OVS_UNUSED)
+{
+ struct timespec ts;
+ int msecs;
+
+ msecs = atoi(argv[1]);
+ if (msecs <= 0) {
+ unixctl_command_reply_error(conn, "invalid MSECS");
+ return;
+ }
+
+ ts.tv_sec = msecs / 1000;
+ ts.tv_nsec = (msecs % 1000) * 1000 * 1000;
+ timespec_add(&warp_offset, &warp_offset, &ts);
+ timespec_add(&monotonic_time, &monotonic_time, &ts);
+ unixctl_command_reply(conn, "warped");
+}
+
+static void
+backtrace_cb(struct unixctl_conn *conn,
+ int argc OVS_UNUSED, const char *argv[] OVS_UNUSED,
+ void *aux OVS_UNUSED)
+{
+ struct ds ds = DS_EMPTY_INITIALIZER;
+
+ assert(HAVE_EXECINFO_H && CACHE_TIME);
+ format_backtraces(&ds);
+ unixctl_command_reply(conn, ds_cstr(&ds));
+ ds_destroy(&ds);
+}
+
+void
+timeval_dummy_register(void)
+{
+ unixctl_command_register("time/stop", "", 0, 0, timeval_stop_cb, NULL);
+ unixctl_command_register("time/warp", "MSECS", 1, 1,
+ timeval_warp_cb, NULL);
+}
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