diff options
Diffstat (limited to 'libnetdata/clocks/clocks.c')
| -rw-r--r-- | libnetdata/clocks/clocks.c | 478 |
1 files changed, 478 insertions, 0 deletions
diff --git a/libnetdata/clocks/clocks.c b/libnetdata/clocks/clocks.c new file mode 100644 index 00000000..adbad045 --- /dev/null +++ b/libnetdata/clocks/clocks.c @@ -0,0 +1,478 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#include "../libnetdata.h" + +// defaults are for compatibility +// call clocks_init() once, to optimize these default settings +static clockid_t clock_boottime_to_use = CLOCK_MONOTONIC; +static clockid_t clock_monotonic_to_use = CLOCK_MONOTONIC; + +// the default clock resolution is 1ms +#define DEFAULT_CLOCK_RESOLUTION_UT ((usec_t)0 * USEC_PER_SEC + (usec_t)1 * USEC_PER_MS) + +// the max clock resolution is 10ms +#define MAX_CLOCK_RESOLUTION_UT ((usec_t)0 * USEC_PER_SEC + (usec_t)10 * USEC_PER_MS) + +usec_t clock_monotonic_resolution = DEFAULT_CLOCK_RESOLUTION_UT; +usec_t clock_realtime_resolution = DEFAULT_CLOCK_RESOLUTION_UT; + +#ifndef HAVE_CLOCK_GETTIME +inline int clock_gettime(clockid_t clk_id __maybe_unused, struct timespec *ts) { + struct timeval tv; + if(unlikely(gettimeofday(&tv, NULL) == -1)) { + netdata_log_error("gettimeofday() failed."); + return -1; + } + ts->tv_sec = tv.tv_sec; + ts->tv_nsec = (long)((tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC); + return 0; +} +#endif + +// Similar to CLOCK_MONOTONIC, but provides access to a raw hardware-based time that is not subject to NTP adjustments +// or the incremental adjustments performed by adjtime(3). This clock does not count time that the system is suspended + +static void test_clock_monotonic_raw(void) { +#ifdef CLOCK_MONOTONIC_RAW + struct timespec ts; + if(clock_gettime(CLOCK_MONOTONIC_RAW, &ts) == -1 && errno == EINVAL) + clock_monotonic_to_use = CLOCK_MONOTONIC; + else + clock_monotonic_to_use = CLOCK_MONOTONIC_RAW; +#else + clock_monotonic_to_use = CLOCK_MONOTONIC; +#endif +} + +// When running a binary with CLOCK_BOOTTIME defined on a system with a linux kernel older than Linux 2.6.39 the +// clock_gettime(2) system call fails with EINVAL. In that case it must fall-back to CLOCK_MONOTONIC. + +static void test_clock_boottime(void) { + struct timespec ts; + if(clock_gettime(CLOCK_BOOTTIME, &ts) == -1 && errno == EINVAL) + clock_boottime_to_use = clock_monotonic_to_use; + else + clock_boottime_to_use = CLOCK_BOOTTIME; +} + +static usec_t get_clock_resolution(clockid_t clock) { + struct timespec ts = { 0 }; + + if(clock_getres(clock, &ts) == 0) { + usec_t ret = (usec_t)ts.tv_sec * USEC_PER_SEC + (usec_t)ts.tv_nsec / NSEC_PER_USEC; + if(!ret && ts.tv_nsec > 0 && ts.tv_nsec < NSEC_PER_USEC) + return (usec_t)1; + + else if(ret > MAX_CLOCK_RESOLUTION_UT) { + nd_log(NDLS_DAEMON, NDLP_ERR, "clock_getres(%d) returned %"PRIu64" usec is out of range, using defaults for clock resolution.", (int)clock, ret); + return DEFAULT_CLOCK_RESOLUTION_UT; + } + + return ret; + } + else { + nd_log(NDLS_DAEMON, NDLP_ERR, "clock_getres(%d) failed, using defaults for clock resolution.", (int)clock); + return DEFAULT_CLOCK_RESOLUTION_UT; + } +} + +// perform any initializations required for clocks + +void clocks_init(void) { + // monotonic raw has to be tested before boottime + test_clock_monotonic_raw(); + + // boottime has to be tested after monotonic coarse + test_clock_boottime(); + + clock_monotonic_resolution = get_clock_resolution(clock_monotonic_to_use); + clock_realtime_resolution = get_clock_resolution(CLOCK_REALTIME); +} + +inline time_t now_sec(clockid_t clk_id) { + struct timespec ts; + if(unlikely(clock_gettime(clk_id, &ts) == -1)) { + netdata_log_error("clock_gettime(%d, ×pec) failed.", clk_id); + return 0; + } + return ts.tv_sec; +} + +inline usec_t now_usec(clockid_t clk_id) { + struct timespec ts; + if(unlikely(clock_gettime(clk_id, &ts) == -1)) { + netdata_log_error("clock_gettime(%d, ×pec) failed.", clk_id); + return 0; + } + return (usec_t)ts.tv_sec * USEC_PER_SEC + (usec_t)(ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC; +} + +inline int now_timeval(clockid_t clk_id, struct timeval *tv) { + struct timespec ts; + + if(unlikely(clock_gettime(clk_id, &ts) == -1)) { + netdata_log_error("clock_gettime(%d, ×pec) failed.", clk_id); + tv->tv_sec = 0; + tv->tv_usec = 0; + return -1; + } + + tv->tv_sec = ts.tv_sec; + tv->tv_usec = (suseconds_t)((ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC); + return 0; +} + +inline time_t now_realtime_sec(void) { + return now_sec(CLOCK_REALTIME); +} + +inline msec_t now_realtime_msec(void) { + return now_usec(CLOCK_REALTIME) / USEC_PER_MS; +} + +inline usec_t now_realtime_usec(void) { + return now_usec(CLOCK_REALTIME); +} + +inline int now_realtime_timeval(struct timeval *tv) { + return now_timeval(CLOCK_REALTIME, tv); +} + +inline time_t now_monotonic_sec(void) { + return now_sec(clock_monotonic_to_use); +} + +inline usec_t now_monotonic_usec(void) { + return now_usec(clock_monotonic_to_use); +} + +inline int now_monotonic_timeval(struct timeval *tv) { + return now_timeval(clock_monotonic_to_use, tv); +} + +inline time_t now_monotonic_high_precision_sec(void) { + return now_sec(CLOCK_MONOTONIC); +} + +inline usec_t now_monotonic_high_precision_usec(void) { + return now_usec(CLOCK_MONOTONIC); +} + +inline int now_monotonic_high_precision_timeval(struct timeval *tv) { + return now_timeval(CLOCK_MONOTONIC, tv); +} + +inline time_t now_boottime_sec(void) { + return now_sec(clock_boottime_to_use); +} + +inline usec_t now_boottime_usec(void) { + return now_usec(clock_boottime_to_use); +} + +inline int now_boottime_timeval(struct timeval *tv) { + return now_timeval(clock_boottime_to_use, tv); +} + +inline usec_t timeval_usec(struct timeval *tv) { + return (usec_t)tv->tv_sec * USEC_PER_SEC + (tv->tv_usec % USEC_PER_SEC); +} + +inline msec_t timeval_msec(struct timeval *tv) { + return (msec_t)tv->tv_sec * MSEC_PER_SEC + ((tv->tv_usec % USEC_PER_SEC) / MSEC_PER_SEC); +} + +inline susec_t dt_usec_signed(struct timeval *now, struct timeval *old) { + usec_t ts1 = timeval_usec(now); + usec_t ts2 = timeval_usec(old); + + if(likely(ts1 >= ts2)) return (susec_t)(ts1 - ts2); + return -((susec_t)(ts2 - ts1)); +} + +inline usec_t dt_usec(struct timeval *now, struct timeval *old) { + usec_t ts1 = timeval_usec(now); + usec_t ts2 = timeval_usec(old); + return (ts1 > ts2) ? (ts1 - ts2) : (ts2 - ts1); +} + +#ifdef __linux__ +void sleep_to_absolute_time(usec_t usec) { + static int einval_printed = 0, enotsup_printed = 0, eunknown_printed = 0; + clockid_t clock = CLOCK_REALTIME; + + struct timespec req = { + .tv_sec = (time_t)(usec / USEC_PER_SEC), + .tv_nsec = (suseconds_t)((usec % USEC_PER_SEC) * NSEC_PER_USEC) + }; + + errno = 0; + int ret = 0; + while( (ret = clock_nanosleep(clock, TIMER_ABSTIME, &req, NULL)) != 0 ) { + if(ret == EINTR) { + errno = 0; + continue; + } + else { + if (ret == EINVAL) { + if (!einval_printed) { + einval_printed++; + netdata_log_error("Invalid time given to clock_nanosleep(): clockid = %d, tv_sec = %lld, tv_nsec = %ld", + clock, + (long long)req.tv_sec, + req.tv_nsec); + } + } else if (ret == ENOTSUP) { + if (!enotsup_printed) { + enotsup_printed++; + netdata_log_error("Invalid clock id given to clock_nanosleep(): clockid = %d, tv_sec = %lld, tv_nsec = %ld", + clock, + (long long)req.tv_sec, + req.tv_nsec); + } + } else { + if (!eunknown_printed) { + eunknown_printed++; + netdata_log_error("Unknown return value %d from clock_nanosleep(): clockid = %d, tv_sec = %lld, tv_nsec = %ld", + ret, + clock, + (long long)req.tv_sec, + req.tv_nsec); + } + } + sleep_usec(usec); + } + } +}; +#endif + +#define HEARTBEAT_ALIGNMENT_STATISTICS_SIZE 10 +netdata_mutex_t heartbeat_alignment_mutex = NETDATA_MUTEX_INITIALIZER; +static size_t heartbeat_alignment_id = 0; + +struct heartbeat_thread_statistics { + size_t sequence; + usec_t dt; +}; +static struct heartbeat_thread_statistics heartbeat_alignment_values[HEARTBEAT_ALIGNMENT_STATISTICS_SIZE] = { 0 }; + +void heartbeat_statistics(usec_t *min_ptr, usec_t *max_ptr, usec_t *average_ptr, size_t *count_ptr) { + struct heartbeat_thread_statistics current[HEARTBEAT_ALIGNMENT_STATISTICS_SIZE]; + static struct heartbeat_thread_statistics old[HEARTBEAT_ALIGNMENT_STATISTICS_SIZE] = { 0 }; + + memcpy(current, heartbeat_alignment_values, sizeof(struct heartbeat_thread_statistics) * HEARTBEAT_ALIGNMENT_STATISTICS_SIZE); + + usec_t min = 0, max = 0, total = 0, average = 0; + size_t i, count = 0; + for(i = 0; i < HEARTBEAT_ALIGNMENT_STATISTICS_SIZE ;i++) { + if(current[i].sequence == old[i].sequence) continue; + usec_t value = current[i].dt - old[i].dt; + + if(!count) { + min = max = total = value; + count = 1; + } + else { + total += value; + if(value < min) min = value; + if(value > max) max = value; + count++; + } + } + if(count) + average = total / count; + + if(min_ptr) *min_ptr = min; + if(max_ptr) *max_ptr = max; + if(average_ptr) *average_ptr = average; + if(count_ptr) *count_ptr = count; + + memcpy(old, current, sizeof(struct heartbeat_thread_statistics) * HEARTBEAT_ALIGNMENT_STATISTICS_SIZE); +} + +inline void heartbeat_init(heartbeat_t *hb) { + hb->realtime = 0ULL; + hb->randomness = (usec_t)250 * USEC_PER_MS + ((usec_t)(now_realtime_usec() * clock_realtime_resolution) % (250 * USEC_PER_MS)); + hb->randomness -= (hb->randomness % clock_realtime_resolution); + + netdata_mutex_lock(&heartbeat_alignment_mutex); + hb->statistics_id = heartbeat_alignment_id; + heartbeat_alignment_id++; + netdata_mutex_unlock(&heartbeat_alignment_mutex); + + if(hb->statistics_id < HEARTBEAT_ALIGNMENT_STATISTICS_SIZE) { + heartbeat_alignment_values[hb->statistics_id].dt = 0; + heartbeat_alignment_values[hb->statistics_id].sequence = 0; + } +} + +// waits for the next heartbeat +// it waits using the monotonic clock +// it returns the dt using the realtime clock + +usec_t heartbeat_next(heartbeat_t *hb, usec_t tick) { + if(unlikely(hb->randomness > tick / 2)) { + // TODO: The heartbeat tick should be specified at the heartbeat_init() function + usec_t tmp = (now_realtime_usec() * clock_realtime_resolution) % (tick / 2); + + nd_log_limit_static_global_var(erl, 10, 0); + nd_log_limit(&erl, NDLS_DAEMON, NDLP_NOTICE, + "heartbeat randomness of %"PRIu64" is too big for a tick of %"PRIu64" - setting it to %"PRIu64"", + hb->randomness, tick, tmp); + hb->randomness = tmp; + } + + usec_t dt; + usec_t now = now_realtime_usec(); + usec_t next = now - (now % tick) + tick + hb->randomness; + + // align the next time we want to the clock resolution + if(next % clock_realtime_resolution) + next = next - (next % clock_realtime_resolution) + clock_realtime_resolution; + + // sleep_usec() has a loop to guarantee we will sleep for at least the requested time. + // According the specs, when we sleep for a relative time, clock adjustments should not affect the duration + // we sleep. + sleep_usec_with_now(next - now, now); + now = now_realtime_usec(); + dt = now - hb->realtime; + + if(hb->statistics_id < HEARTBEAT_ALIGNMENT_STATISTICS_SIZE) { + heartbeat_alignment_values[hb->statistics_id].dt += now - next; + heartbeat_alignment_values[hb->statistics_id].sequence++; + } + + if(unlikely(now < next)) { + errno = 0; + nd_log_limit_static_global_var(erl, 10, 0); + nd_log_limit(&erl, NDLS_DAEMON, NDLP_NOTICE, + "heartbeat clock: woke up %"PRIu64" microseconds earlier than expected " + "(can be due to the CLOCK_REALTIME set to the past).", + next - now); + } + else if(unlikely(now - next > tick / 2)) { + errno = 0; + nd_log_limit_static_global_var(erl, 10, 0); + nd_log_limit(&erl, NDLS_DAEMON, NDLP_NOTICE, + "heartbeat clock: woke up %"PRIu64" microseconds later than expected " + "(can be due to system load or the CLOCK_REALTIME set to the future).", + now - next); + } + + if(unlikely(!hb->realtime)) { + // the first time return zero + dt = 0; + } + + hb->realtime = now; + return dt; +} + +void sleep_usec_with_now(usec_t usec, usec_t started_ut) { + // we expect microseconds (1.000.000 per second) + // but timespec is nanoseconds (1.000.000.000 per second) + struct timespec rem = { 0, 0 }, req = { + .tv_sec = (time_t) (usec / USEC_PER_SEC), + .tv_nsec = (suseconds_t) ((usec % USEC_PER_SEC) * NSEC_PER_USEC) + }; + + // make sure errno is not EINTR + errno = 0; + + if(!started_ut) + started_ut = now_realtime_usec(); + + usec_t end_ut = started_ut + usec; + + while (nanosleep(&req, &rem) != 0) { + if (likely(errno == EINTR && (rem.tv_sec || rem.tv_nsec))) { + req = rem; + rem = (struct timespec){ 0, 0 }; + + // break an infinite loop + errno = 0; + + usec_t now_ut = now_realtime_usec(); + if(now_ut >= end_ut) + break; + + usec_t remaining_ut = (usec_t)req.tv_sec * USEC_PER_SEC + (usec_t)req.tv_nsec * NSEC_PER_USEC > usec; + usec_t check_ut = now_ut - started_ut; + if(remaining_ut > check_ut) { + req = (struct timespec){ + .tv_sec = (time_t) ( check_ut / USEC_PER_SEC), + .tv_nsec = (suseconds_t) ((check_ut % USEC_PER_SEC) * NSEC_PER_USEC) + }; + } + } + else { + netdata_log_error("Cannot nanosleep() for %"PRIu64" microseconds.", usec); + break; + } + } +} + +static inline collected_number uptime_from_boottime(void) { +#ifdef CLOCK_BOOTTIME_IS_AVAILABLE + return (collected_number)(now_boottime_usec() / USEC_PER_MS); +#else + netdata_log_error("uptime cannot be read from CLOCK_BOOTTIME on this system."); + return 0; +#endif +} + +static procfile *read_proc_uptime_ff = NULL; +static inline collected_number read_proc_uptime(char *filename) { + if(unlikely(!read_proc_uptime_ff)) { + read_proc_uptime_ff = procfile_open(filename, " \t", PROCFILE_FLAG_DEFAULT); + if(unlikely(!read_proc_uptime_ff)) return 0; + } + + read_proc_uptime_ff = procfile_readall(read_proc_uptime_ff); + if(unlikely(!read_proc_uptime_ff)) return 0; + + if(unlikely(procfile_lines(read_proc_uptime_ff) < 1)) { + netdata_log_error("/proc/uptime has no lines."); + return 0; + } + if(unlikely(procfile_linewords(read_proc_uptime_ff, 0) < 1)) { + netdata_log_error("/proc/uptime has less than 1 word in it."); + return 0; + } + + return (collected_number)(strtondd(procfile_lineword(read_proc_uptime_ff, 0, 0), NULL) * 1000.0); +} + +inline collected_number uptime_msec(char *filename){ + static int use_boottime = -1; + + if(unlikely(use_boottime == -1)) { + collected_number uptime_boottime = uptime_from_boottime(); + collected_number uptime_proc = read_proc_uptime(filename); + + long long delta = (long long)uptime_boottime - (long long)uptime_proc; + if(delta < 0) delta = -delta; + + if(delta <= 1000 && uptime_boottime != 0) { + procfile_close(read_proc_uptime_ff); + netdata_log_info("Using now_boottime_usec() for uptime (dt is %lld ms)", delta); + use_boottime = 1; + } + else if(uptime_proc != 0) { + netdata_log_info("Using /proc/uptime for uptime (dt is %lld ms)", delta); + use_boottime = 0; + } + else { + netdata_log_error("Cannot find any way to read uptime on this system."); + return 1; + } + } + + collected_number uptime; + if(use_boottime) + uptime = uptime_from_boottime(); + else + uptime = read_proc_uptime(filename); + + return uptime; +} |