2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
29 #include <sys/resource.h>
33 #include "dynamic-string.h"
34 #include "fatal-signal.h"
40 #ifndef HAVE_EXECINFO_H
41 #define HAVE_EXECINFO_H 0
44 VLOG_DEFINE_THIS_MODULE(timeval);
46 /* The clock to use for measuring time intervals. This is CLOCK_MONOTONIC by
47 * preference, but on systems that don't have a monotonic clock we fall back
48 * to CLOCK_REALTIME. */
49 static clockid_t monotonic_clock;
51 /* Has a timer tick occurred? Only relevant if CACHE_TIME is true.
53 * We initialize these to true to force time_init() to get called on the first
54 * call to time_msec() or another function that queries the current time. */
55 static volatile sig_atomic_t wall_tick = true;
56 static volatile sig_atomic_t monotonic_tick = true;
58 /* The current time, as of the last refresh. */
59 static struct timespec wall_time;
60 static struct timespec monotonic_time;
62 /* The monotonic time at which the time module was initialized. */
63 static long long int boot_time;
65 /* features for use by unit tests. */
66 static struct timespec warp_offset; /* Offset added to monotonic_time. */
67 static bool time_stopped; /* Disables real-time updates, if true. */
69 /* Time in milliseconds at which to die with SIGALRM (if not LLONG_MAX). */
70 static long long int deadline = LLONG_MAX;
73 void *backtrace[32]; /* Populated by backtrace(). */
74 size_t n_frames; /* Number of frames in 'backtrace'. */
78 static struct trace traces[MAX_TRACES];
79 static size_t trace_head = 0;
81 static void set_up_timer(void);
82 static void set_up_signal(int flags);
83 static void sigalrm_handler(int);
84 static void refresh_wall_if_ticked(void);
85 static void refresh_monotonic_if_ticked(void);
86 static void block_sigalrm(sigset_t *);
87 static void unblock_sigalrm(const sigset_t *);
88 static void log_poll_interval(long long int last_wakeup);
89 static struct rusage *get_recent_rusage(void);
90 static void refresh_rusage(void);
91 static void timespec_add(struct timespec *sum,
92 const struct timespec *a, const struct timespec *b);
93 static unixctl_cb_func backtrace_cb;
95 /* Initializes the timetracking module, if not already initialized. */
106 memset(traces, 0, sizeof traces);
108 if (HAVE_EXECINFO_H && CACHE_TIME) {
109 unixctl_command_register("backtrace", "", 0, 0, backtrace_cb, NULL);
114 if (!clock_gettime(CLOCK_MONOTONIC, &monotonic_time)) {
115 monotonic_clock = CLOCK_MONOTONIC;
117 monotonic_clock = CLOCK_REALTIME;
118 VLOG_DBG("monotonic timer not available");
121 set_up_signal(SA_RESTART);
124 boot_time = time_msec();
128 set_up_signal(int flags)
132 memset(&sa, 0, sizeof sa);
133 sa.sa_handler = sigalrm_handler;
134 sigemptyset(&sa.sa_mask);
136 xsigaction(SIGALRM, &sa, NULL);
139 /* Remove SA_RESTART from the flags for SIGALRM, so that any system call that
140 * is interrupted by the periodic timer interrupt will return EINTR instead of
141 * continuing after the signal handler returns.
143 * time_disable_restart() and time_enable_restart() may be usefully wrapped
144 * around function calls that might otherwise block forever unless interrupted
147 * time_disable_restart();
148 * fcntl(fd, F_SETLKW, &lock);
149 * time_enable_restart();
152 time_disable_restart(void)
158 /* Add SA_RESTART to the flags for SIGALRM, so that any system call that
159 * is interrupted by the periodic timer interrupt will continue after the
160 * signal handler returns instead of returning EINTR. */
162 time_enable_restart(void)
165 set_up_signal(SA_RESTART);
171 static timer_t timer_id; /* "static" to avoid apparent memory leak. */
172 struct itimerspec itimer;
178 if (timer_create(monotonic_clock, NULL, &timer_id)) {
179 VLOG_FATAL("timer_create failed (%s)", strerror(errno));
182 itimer.it_interval.tv_sec = 0;
183 itimer.it_interval.tv_nsec = TIME_UPDATE_INTERVAL * 1000 * 1000;
184 itimer.it_value = itimer.it_interval;
186 if (timer_settime(timer_id, 0, &itimer, NULL)) {
187 VLOG_FATAL("timer_settime failed (%s)", strerror(errno));
191 /* Set up the interval timer, to ensure that time advances even without calling
194 * A child created with fork() does not inherit the parent's interval timer, so
195 * this function needs to be called from the child after fork(). */
207 clock_gettime(CLOCK_REALTIME, &wall_time);
212 refresh_monotonic(void)
217 if (monotonic_clock == CLOCK_MONOTONIC) {
218 clock_gettime(monotonic_clock, &monotonic_time);
220 refresh_wall_if_ticked();
221 monotonic_time = wall_time;
223 timespec_add(&monotonic_time, &monotonic_time, &warp_offset);
225 monotonic_tick = false;
229 /* Forces a refresh of the current time from the kernel. It is not usually
230 * necessary to call this function, since the time will be refreshed
231 * automatically at least every TIME_UPDATE_INTERVAL milliseconds. If
232 * CACHE_TIME is false, we will always refresh the current time so this
233 * function has no effect. */
237 wall_tick = monotonic_tick = true;
240 /* Returns a monotonic timer, in seconds. */
244 refresh_monotonic_if_ticked();
245 return monotonic_time.tv_sec;
248 /* Returns the current time, in seconds. */
252 refresh_wall_if_ticked();
253 return wall_time.tv_sec;
256 /* Returns a monotonic timer, in ms (within TIME_UPDATE_INTERVAL ms). */
260 refresh_monotonic_if_ticked();
261 return timespec_to_msec(&monotonic_time);
264 /* Returns the current time, in ms (within TIME_UPDATE_INTERVAL ms). */
268 refresh_wall_if_ticked();
269 return timespec_to_msec(&wall_time);
272 /* Stores a monotonic timer, accurate within TIME_UPDATE_INTERVAL ms, into
275 time_timespec(struct timespec *ts)
277 refresh_monotonic_if_ticked();
278 *ts = monotonic_time;
281 /* Stores the current time, accurate within TIME_UPDATE_INTERVAL ms, into
284 time_wall_timespec(struct timespec *ts)
286 refresh_wall_if_ticked();
290 /* Configures the program to die with SIGALRM 'secs' seconds from now, if
291 * 'secs' is nonzero, or disables the feature if 'secs' is zero. */
293 time_alarm(unsigned int secs)
306 block_sigalrm(&oldsigs);
307 deadline = now < LLONG_MAX - msecs ? now + msecs : LLONG_MAX;
308 unblock_sigalrm(&oldsigs);
311 /* Like poll(), except:
313 * - The timeout is specified as an absolute time, as defined by
314 * time_msec(), instead of a duration.
316 * - On error, returns a negative error code (instead of setting errno).
318 * - If interrupted by a signal, retries automatically until the original
319 * timeout is reached. (Because of this property, this function will
320 * never return -EINTR.)
322 * - As a side effect, refreshes the current time (like time_refresh()).
324 * Stores the number of milliseconds elapsed during poll in '*elapsed'. */
326 time_poll(struct pollfd *pollfds, int n_pollfds, long long int timeout_when,
329 static long long int last_wakeup = 0;
337 log_poll_interval(last_wakeup);
343 timeout_when = MIN(timeout_when, deadline);
346 long long int now = time_msec();
349 if (now >= timeout_when) {
351 } else if ((unsigned long long int) timeout_when - now > INT_MAX) {
354 time_left = timeout_when - now;
357 retval = poll(pollfds, n_pollfds, time_left);
363 if (deadline <= time_msec()) {
364 fatal_signal_handler(SIGALRM);
371 if (retval != -EINTR) {
375 if (!blocked && CACHE_TIME) {
376 block_sigalrm(&oldsigs);
381 unblock_sigalrm(&oldsigs);
383 last_wakeup = time_msec();
385 *elapsed = last_wakeup - start;
390 sigalrm_handler(int sig_nr OVS_UNUSED)
393 monotonic_tick = true;
397 struct trace *trace = &traces[trace_head];
399 trace->n_frames = backtrace(trace->backtrace,
400 ARRAY_SIZE(trace->backtrace));
401 trace_head = (trace_head + 1) % MAX_TRACES;
407 refresh_wall_if_ticked(void)
409 if (!CACHE_TIME || wall_tick) {
415 refresh_monotonic_if_ticked(void)
417 if (!CACHE_TIME || monotonic_tick) {
423 block_sigalrm(sigset_t *oldsigs)
426 sigemptyset(&sigalrm);
427 sigaddset(&sigalrm, SIGALRM);
428 xsigprocmask(SIG_BLOCK, &sigalrm, oldsigs);
432 unblock_sigalrm(const sigset_t *oldsigs)
434 xsigprocmask(SIG_SETMASK, oldsigs, NULL);
438 timespec_to_msec(const struct timespec *ts)
440 return (long long int) ts->tv_sec * 1000 + ts->tv_nsec / (1000 * 1000);
444 timeval_to_msec(const struct timeval *tv)
446 return (long long int) tv->tv_sec * 1000 + tv->tv_usec / 1000;
449 /* Returns the monotonic time at which the "time" module was initialized, in
459 xgettimeofday(struct timeval *tv)
461 if (gettimeofday(tv, NULL) == -1) {
462 VLOG_FATAL("gettimeofday failed (%s)", strerror(errno));
467 timeval_diff_msec(const struct timeval *a, const struct timeval *b)
469 return timeval_to_msec(a) - timeval_to_msec(b);
473 timespec_add(struct timespec *sum,
474 const struct timespec *a,
475 const struct timespec *b)
479 tmp.tv_sec = a->tv_sec + b->tv_sec;
480 tmp.tv_nsec = a->tv_nsec + b->tv_nsec;
481 if (tmp.tv_nsec >= 1000 * 1000 * 1000) {
482 tmp.tv_nsec -= 1000 * 1000 * 1000;
490 log_poll_interval(long long int last_wakeup)
492 long long int interval = time_msec() - last_wakeup;
494 if (interval >= 1000) {
495 const struct rusage *last_rusage = get_recent_rusage();
496 struct rusage rusage;
498 getrusage(RUSAGE_SELF, &rusage);
499 VLOG_WARN("Unreasonably long %lldms poll interval"
500 " (%lldms user, %lldms system)",
502 timeval_diff_msec(&rusage.ru_utime,
503 &last_rusage->ru_utime),
504 timeval_diff_msec(&rusage.ru_stime,
505 &last_rusage->ru_stime));
506 if (rusage.ru_minflt > last_rusage->ru_minflt
507 || rusage.ru_majflt > last_rusage->ru_majflt) {
508 VLOG_WARN("faults: %ld minor, %ld major",
509 rusage.ru_minflt - last_rusage->ru_minflt,
510 rusage.ru_majflt - last_rusage->ru_majflt);
512 if (rusage.ru_inblock > last_rusage->ru_inblock
513 || rusage.ru_oublock > last_rusage->ru_oublock) {
514 VLOG_WARN("disk: %ld reads, %ld writes",
515 rusage.ru_inblock - last_rusage->ru_inblock,
516 rusage.ru_oublock - last_rusage->ru_oublock);
518 if (rusage.ru_nvcsw > last_rusage->ru_nvcsw
519 || rusage.ru_nivcsw > last_rusage->ru_nivcsw) {
520 VLOG_WARN("context switches: %ld voluntary, %ld involuntary",
521 rusage.ru_nvcsw - last_rusage->ru_nvcsw,
522 rusage.ru_nivcsw - last_rusage->ru_nivcsw);
528 /* CPU usage tracking. */
531 long long int when; /* Time that this sample was taken. */
532 unsigned long long int cpu; /* Total user+system CPU usage when sampled. */
535 static struct rusage recent_rusage;
536 static struct cpu_usage older = { LLONG_MIN, 0 };
537 static struct cpu_usage newer = { LLONG_MIN, 0 };
538 static int cpu_usage = -1;
540 static struct rusage *
541 get_recent_rusage(void)
543 return &recent_rusage;
552 getrusage(RUSAGE_SELF, &recent_rusage);
554 if (now >= newer.when + 3 * 1000) {
557 newer.cpu = (timeval_to_msec(&recent_rusage.ru_utime) +
558 timeval_to_msec(&recent_rusage.ru_stime));
560 if (older.when != LLONG_MIN && newer.cpu > older.cpu) {
561 unsigned int dividend = newer.cpu - older.cpu;
562 unsigned int divisor = (newer.when - older.when) / 100;
563 cpu_usage = divisor > 0 ? dividend / divisor : -1;
570 /* Returns an estimate of this process's CPU usage, as a percentage, over the
571 * past few seconds of wall-clock time. Returns -1 if no estimate is available
572 * (which will happen if the process has not been running long enough to have
573 * an estimate, and can happen for other reasons as well). */
581 format_backtraces(struct ds *ds)
590 block_sigalrm(&oldsigs);
592 for (i = 0; i < MAX_TRACES; i++) {
593 struct trace *trace = &traces[i];
597 if (!trace->n_frames) {
601 frame_strs = backtrace_symbols(trace->backtrace, trace->n_frames);
603 ds_put_format(ds, "Backtrace %zu\n", i + 1);
604 for (j = 0; j < trace->n_frames; j++) {
605 ds_put_format(ds, "%s\n", frame_strs[j]);
607 ds_put_cstr(ds, "\n");
612 unblock_sigalrm(&oldsigs);
617 /* Unixctl interface. */
619 /* "time/stop" stops the monotonic time returned by e.g. time_msec() from
620 * advancing, except due to later calls to "time/warp". */
622 timeval_stop_cb(struct unixctl_conn *conn,
623 int argc OVS_UNUSED, const char *argv[] OVS_UNUSED,
624 void *aux OVS_UNUSED)
627 unixctl_command_reply(conn, NULL);
630 /* "time/warp MSECS" advances the current monotonic time by the specified
631 * number of milliseconds. Unless "time/stop" has also been executed, the
632 * monotonic clock continues to tick forward at the normal rate afterward.
634 * Does not affect wall clock readings. */
636 timeval_warp_cb(struct unixctl_conn *conn,
637 int argc OVS_UNUSED, const char *argv[], void *aux OVS_UNUSED)
642 msecs = atoi(argv[1]);
644 unixctl_command_reply_error(conn, "invalid MSECS");
648 ts.tv_sec = msecs / 1000;
649 ts.tv_nsec = (msecs % 1000) * 1000 * 1000;
650 timespec_add(&warp_offset, &warp_offset, &ts);
651 timespec_add(&monotonic_time, &monotonic_time, &ts);
652 unixctl_command_reply(conn, "warped");
656 backtrace_cb(struct unixctl_conn *conn,
657 int argc OVS_UNUSED, const char *argv[] OVS_UNUSED,
658 void *aux OVS_UNUSED)
660 struct ds ds = DS_EMPTY_INITIALIZER;
662 assert(HAVE_EXECINFO_H && CACHE_TIME);
663 format_backtraces(&ds);
664 unixctl_command_reply(conn, ds_cstr(&ds));
669 timeval_dummy_register(void)
671 unixctl_command_register("time/stop", "", 0, 0, timeval_stop_cb, NULL);
672 unixctl_command_register("time/warp", "MSECS", 1, 1,
673 timeval_warp_cb, NULL);