/* * General time-keeping code and variables * * Copyright 2000-2021 Willy Tarreau * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * */ #include #include #include #ifdef USE_THREAD #include #endif #include #include #include #include #include #include #include struct timeval start_date; /* the process's start date in wall-clock time */ struct timeval ready_date; /* date when the process was considered ready */ ullong start_time_ns; /* the process's start date in internal monotonic time (ns) */ volatile ullong global_now_ns; /* common monotonic date between all threads, in ns (wraps every 585 yr) */ volatile uint global_now_ms; /* common monotonic date in milliseconds (may wrap) */ THREAD_ALIGNED(64) static llong now_offset; /* global offset between system time and global time in ns */ THREAD_LOCAL ullong now_ns; /* internal monotonic date derived from real clock, in ns (wraps every 585 yr) */ THREAD_LOCAL uint now_ms; /* internal monotonic date in milliseconds (may wrap) */ THREAD_LOCAL struct timeval date; /* the real current date (wall-clock time) */ static THREAD_LOCAL struct timeval before_poll; /* system date before calling poll() */ static THREAD_LOCAL struct timeval after_poll; /* system date after leaving poll() */ static THREAD_LOCAL unsigned int samp_time; /* total elapsed time over current sample */ static THREAD_LOCAL unsigned int idle_time; /* total idle time over current sample */ static THREAD_LOCAL unsigned int iso_time_sec; /* last iso time value for this thread */ static THREAD_LOCAL char iso_time_str[34]; /* ISO time representation of gettimeofday() */ #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME) static clockid_t per_thread_clock_id[MAX_THREADS]; #endif /* returns the system's monotonic time in nanoseconds if supported, otherwise zero */ uint64_t now_mono_time(void) { uint64_t ret = 0; #if defined(_POSIX_TIMERS) && defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_MONOTONIC_CLOCK) struct timespec ts; clock_gettime(CLOCK_MONOTONIC, &ts); ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec; #endif return ret; } /* Returns the system's monotonic time in nanoseconds. * Uses the coarse clock source if supported (for fast but * less precise queries with limited resource usage). * Fallback to now_mono_time() if coarse source is not supported, * which may itself return 0 if not supported either. */ uint64_t now_mono_time_fast(void) { #if defined(CLOCK_MONOTONIC_COARSE) struct timespec ts; clock_gettime(CLOCK_MONOTONIC_COARSE, &ts); return (ts.tv_sec * 1000000000ULL + ts.tv_nsec); #else /* fallback to regular mono time, * returns 0 if not supported */ return now_mono_time(); #endif } /* returns the current thread's cumulated CPU time in nanoseconds if supported, otherwise zero */ uint64_t now_cpu_time(void) { uint64_t ret = 0; #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME) struct timespec ts; clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts); ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec; #endif return ret; } /* Returns the current thread's cumulated CPU time in nanoseconds. * * thread_local timer is cached so that call is less precise but also less * expensive if heavily used. * We use the mono time as a cache expiration hint since now_cpu_time() is * known to be much more expensive than now_mono_time_fast() on systems * supporting the COARSE clock source. * * Returns 0 if either now_mono_time_fast() or now_cpu_time() are not * supported. */ uint64_t now_cpu_time_fast(void) { static THREAD_LOCAL uint64_t mono_cache = 0; static THREAD_LOCAL uint64_t cpu_cache = 0; uint64_t mono_cur; mono_cur = now_mono_time_fast(); if (unlikely(mono_cur != mono_cache)) { /* global mono clock was updated: local cache is outdated */ cpu_cache = now_cpu_time(); mono_cache = mono_cur; } return cpu_cache; } /* returns another thread's cumulated CPU time in nanoseconds if supported, otherwise zero */ uint64_t now_cpu_time_thread(int thr) { uint64_t ret = 0; #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME) struct timespec ts; clock_gettime(per_thread_clock_id[thr], &ts); ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec; #endif return ret; } /* set the clock source for the local thread */ void clock_set_local_source(void) { #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME) #ifdef USE_THREAD pthread_getcpuclockid(pthread_self(), &per_thread_clock_id[tid]); #else per_thread_clock_id[tid] = CLOCK_THREAD_CPUTIME_ID; #endif #endif } /* registers a timer of type timer_t delivering signal with value * . It tries on the current thread's clock ID first and falls back to * CLOCK_REALTIME. Returns non-zero on success, 1 on failure. */ int clock_setup_signal_timer(void *tmr, int sig, int val) { int ret = 0; #if defined(USE_RT) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME) struct sigevent sev = { }; timer_t *timer = tmr; sigset_t set; /* unblock the WDTSIG signal we intend to use */ sigemptyset(&set); sigaddset(&set, WDTSIG); ha_sigmask(SIG_UNBLOCK, &set, NULL); /* this timer will signal WDTSIG when it fires, with tid in the si_int * field (important since any thread will receive the signal). */ sev.sigev_notify = SIGEV_SIGNAL; sev.sigev_signo = sig; sev.sigev_value.sival_int = val; if (timer_create(per_thread_clock_id[tid], &sev, timer) != -1 || timer_create(CLOCK_REALTIME, &sev, timer) != -1) ret = 1; #endif return ret; } /* clock_update_date: sets to system time, and sets to something * as close as possible to real time, following a monotonic function. The main * principle consists in detecting backwards and forwards time jumps and adjust * an offset to correct them. This function should be called once after each * poll, and never farther apart than MAX_DELAY_MS*2. The poll's timeout should * be passed in , and the return value in (a non-zero * value means that we have not expired the timeout). * * clock_init_process_date() must have been called once first, and * clock_init_thread_date() must also have been called once for each thread. * * An offset is used to adjust the current time (date), to figure a monotonic * local time (now_ns). The offset is not critical, as it is only updated after * a clock jump is detected. From this point all threads will apply it to their * locally measured time, and will then agree around a common monotonic * global_now_ns value that serves to further refine their local time. Both * now_ns and global_now_ns are 64-bit integers counting nanoseconds since a * vague reference (it starts roughly 20s before the next wrap-around of the * millisecond counter after boot). The offset is also an integral number of * nanoseconds, but it's signed so that the clock can be adjusted in the two * directions. */ void clock_update_local_date(int max_wait, int interrupted) { struct timeval min_deadline, max_deadline; gettimeofday(&date, NULL); /* compute the minimum and maximum local date we may have reached based * on our past date and the associated timeout. There are three possible * extremities: * - the new date cannot be older than before_poll * - if not interrupted, the new date cannot be older than * before_poll+max_wait * - in any case the new date cannot be newer than * before_poll+max_wait+some margin (100ms used here). * In case of violation, we'll ignore the current date and instead * restart from the last date we knew. */ _tv_ms_add(&min_deadline, &before_poll, max_wait); _tv_ms_add(&max_deadline, &before_poll, max_wait + 100); if (unlikely(__tv_islt(&date, &before_poll) || // big jump backwards (!interrupted && __tv_islt(&date, &min_deadline)) || // small jump backwards __tv_islt(&max_deadline, &date))) { // big jump forwards if (!interrupted) now_ns += ms_to_ns(max_wait); } else { /* The date is still within expectations. Let's apply the * now_offset to the system date. Note: ofs if made of two * independent signed ints. */ now_ns = tv_to_ns(&date) + HA_ATOMIC_LOAD(&now_offset); } now_ms = ns_to_ms(now_ns); } void clock_update_global_date() { ullong old_now_ns; uint old_now_ms; /* now that we have bounded the local time, let's check if it's * realistic regarding the global date, which only moves forward, * otherwise catch up. */ old_now_ns = _HA_ATOMIC_LOAD(&global_now_ns); old_now_ms = global_now_ms; do { if (now_ns < old_now_ns) now_ns = old_now_ns; /* now is expected to be the most accurate date, * equal to or newer. Updating the global * date too often causes extreme contention and is not * needed: it's only used to help threads run at the * same date in case of local drift, and the global date, * which changes, is only used by freq counters (a choice * which is debatable by the way since it changes under us). * Tests have seen that the contention can be reduced from * 37% in this function to almost 0% when keeping clocks * synchronized no better than 32 microseconds, so that's * what we're doing here. */ now_ms = ns_to_ms(now_ns); if (!((now_ns ^ old_now_ns) & ~0x7FFFULL)) return; /* let's try to update the global_now_ns (both in nanoseconds * and ms forms) or loop again. */ } while ((!_HA_ATOMIC_CAS(&global_now_ns, &old_now_ns, now_ns) || (now_ms != old_now_ms && !_HA_ATOMIC_CAS(&global_now_ms, &old_now_ms, now_ms))) && __ha_cpu_relax()); /* and are now updated to the last value of * global_now_ns and global_now_ms, which were also monotonically * updated. We can compute the latest offset, we don't care who writes * it last, the variations will not break the monotonic property. */ HA_ATOMIC_STORE(&now_offset, now_ns - tv_to_ns(&date)); } /* must be called once at boot to initialize some global variables */ void clock_init_process_date(void) { now_offset = 0; gettimeofday(&date, NULL); after_poll = before_poll = date; now_ns = global_now_ns = tv_to_ns(&date); global_now_ms = ns_to_ms(now_ns); /* force time to wrap 20s after boot: we first compute the time offset * that once applied to the wall-clock date will make the local time * wrap in 5 seconds. This offset is applied to the process-wide time, * and will be used to recompute the local time, both of which will * match and continue from this shifted date. */ now_offset = sec_to_ns((uint)((uint)(-global_now_ms) / 1000U - BOOT_TIME_WRAP_SEC)); global_now_ns += now_offset; now_ns = global_now_ns; now_ms = global_now_ms = ns_to_ms(now_ns); th_ctx->idle_pct = 100; clock_update_date(0, 1); } void clock_adjust_now_offset(void) { HA_ATOMIC_STORE(&now_offset, now_ns - tv_to_ns(&date)); } /* must be called once per thread to initialize their thread-local variables. * Note that other threads might also be initializing and running in parallel. */ void clock_init_thread_date(void) { gettimeofday(&date, NULL); after_poll = before_poll = date; now_ns = _HA_ATOMIC_LOAD(&global_now_ns); th_ctx->idle_pct = 100; th_ctx->prev_cpu_time = now_cpu_time(); clock_update_date(0, 1); } /* report the average CPU idle percentage over all running threads, between 0 and 100 */ uint clock_report_idle(void) { uint total = 0; uint rthr = 0; uint thr; for (thr = 0; thr < MAX_THREADS; thr++) { if (!ha_thread_info[thr].tg || !(ha_thread_info[thr].tg->threads_enabled & ha_thread_info[thr].ltid_bit)) continue; total += HA_ATOMIC_LOAD(&ha_thread_ctx[thr].idle_pct); rthr++; } return rthr ? total / rthr : 0; } /* Update the idle time value twice a second, to be called after * clock_update_date() when called after poll(), and currently called only by * clock_leaving_poll() below. It relies on to be updated to * the system time before calling poll(). */ static inline void clock_measure_idle(void) { /* Let's compute the idle to work ratio. We worked between after_poll * and before_poll, and slept between before_poll and date. The idle_pct * is updated at most twice every second. Note that the current second * rarely changes so we avoid a multiply when not needed. */ int delta; if ((delta = date.tv_sec - before_poll.tv_sec)) delta *= 1000000; idle_time += delta + (date.tv_usec - before_poll.tv_usec); if ((delta = date.tv_sec - after_poll.tv_sec)) delta *= 1000000; samp_time += delta + (date.tv_usec - after_poll.tv_usec); after_poll.tv_sec = date.tv_sec; after_poll.tv_usec = date.tv_usec; if (samp_time < 500000) return; HA_ATOMIC_STORE(&th_ctx->idle_pct, (100ULL * idle_time + samp_time / 2) / samp_time); idle_time = samp_time = 0; } /* Collect date and time information after leaving poll(). must be * set to the maximum sleep time passed to poll (in milliseconds), and * must be zero if the poller reached the timeout or non-zero * otherwise, which generally is provided by the poller's return value. */ void clock_leaving_poll(int timeout, int interrupted) { clock_measure_idle(); th_ctx->prev_cpu_time = now_cpu_time(); th_ctx->prev_mono_time = now_mono_time(); } /* Collect date and time information before calling poll(). This will be used * to count the run time of the past loop and the sleep time of the next poll. * It also compares the elapsed and cpu times during the activity period to * estimate the amount of stolen time, which is reported if higher than half * a millisecond. */ void clock_entering_poll(void) { uint64_t new_mono_time; uint64_t new_cpu_time; uint32_t run_time; int64_t stolen; gettimeofday(&before_poll, NULL); run_time = (before_poll.tv_sec - after_poll.tv_sec) * 1000000U + (before_poll.tv_usec - after_poll.tv_usec); new_cpu_time = now_cpu_time(); new_mono_time = now_mono_time(); if (th_ctx->prev_cpu_time && th_ctx->prev_mono_time) { new_cpu_time -= th_ctx->prev_cpu_time; new_mono_time -= th_ctx->prev_mono_time; stolen = new_mono_time - new_cpu_time; if (unlikely(stolen >= 500000)) { stolen /= 500000; /* more than half a millisecond difference might * indicate an undesired preemption. */ report_stolen_time(stolen); } } /* update the average runtime */ activity_count_runtime(run_time); } /* returns the current date as returned by gettimeofday() in ISO+microsecond * format. It uses a thread-local static variable that the reader can consume * for as long as it wants until next call. Thus, do not call it from a signal * handler. If is non-0, a trailing space will be added. It will always * return exactly 32 or 33 characters (depending on padding) and will always be * zero-terminated, thus it will always fit into a 34 bytes buffer. * This also always include the local timezone (in +/-HH:mm format) . */ char *timeofday_as_iso_us(int pad) { struct timeval new_date; struct tm tm; const char *offset; char c; gettimeofday(&new_date, NULL); if (new_date.tv_sec != iso_time_sec || !new_date.tv_sec) { get_localtime(new_date.tv_sec, &tm); offset = get_gmt_offset(new_date.tv_sec, &tm); if (unlikely(strftime(iso_time_str, sizeof(iso_time_str), "%Y-%m-%dT%H:%M:%S.000000+00:00", &tm) != 32)) strlcpy2(iso_time_str, "YYYY-mm-ddTHH:MM:SS.000000-00:00", sizeof(iso_time_str)); // make the failure visible but respect format. iso_time_str[26] = offset[0]; iso_time_str[27] = offset[1]; iso_time_str[28] = offset[2]; iso_time_str[30] = offset[3]; iso_time_str[31] = offset[4]; iso_time_sec = new_date.tv_sec; } /* utoa_pad adds a trailing 0 so we save the char for restore */ c = iso_time_str[26]; utoa_pad(new_date.tv_usec, iso_time_str + 20, 7); iso_time_str[26] = c; if (pad) { iso_time_str[32] = ' '; iso_time_str[33] = 0; } return iso_time_str; }