diff options
Diffstat (limited to 'libnetdata/clocks')
-rw-r--r-- | libnetdata/clocks/Makefile.am | 8 | ||||
-rw-r--r-- | libnetdata/clocks/README.md | 5 | ||||
-rw-r--r-- | libnetdata/clocks/clocks.c | 432 | ||||
-rw-r--r-- | libnetdata/clocks/clocks.h | 160 |
4 files changed, 605 insertions, 0 deletions
diff --git a/libnetdata/clocks/Makefile.am b/libnetdata/clocks/Makefile.am new file mode 100644 index 0000000..161784b --- /dev/null +++ b/libnetdata/clocks/Makefile.am @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-3.0-or-later + +AUTOMAKE_OPTIONS = subdir-objects +MAINTAINERCLEANFILES = $(srcdir)/Makefile.in + +dist_noinst_DATA = \ + README.md \ + $(NULL) diff --git a/libnetdata/clocks/README.md b/libnetdata/clocks/README.md new file mode 100644 index 0000000..3a7ce55 --- /dev/null +++ b/libnetdata/clocks/README.md @@ -0,0 +1,5 @@ +<!-- +custom_edit_url: https://github.com/netdata/netdata/edit/master/libnetdata/clocks/README.md +--> + + diff --git a/libnetdata/clocks/clocks.c b/libnetdata/clocks/clocks.c new file mode 100644 index 0000000..cabc000 --- /dev/null +++ b/libnetdata/clocks/clocks.c @@ -0,0 +1,432 @@ +// 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; + +usec_t clock_monotonic_resolution = 1000; +usec_t clock_realtime_resolution = 1000; + +#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)) { + 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; + clock_getres(clock, &ts); + return ts.tv_sec * USEC_PER_SEC + ts.tv_nsec * NSEC_PER_USEC; +} + +// 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); + + // if for any reason these are zero, netdata will crash + // since we use them as modulo to calculations + if(!clock_realtime_resolution) + clock_realtime_resolution = 1000; + + if(!clock_monotonic_resolution) + clock_monotonic_resolution = 1000; +} + +inline time_t now_sec(clockid_t clk_id) { + struct timespec ts; + if(unlikely(clock_gettime(clk_id, &ts) == -1)) { + 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)) { + error("clock_gettime(%d, ×pec) failed.", clk_id); + return 0; + } + return (usec_t)ts.tv_sec * USEC_PER_SEC + (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)) { + 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 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) + }; + + int ret = 0; + while( (ret = clock_nanosleep(clock, TIMER_ABSTIME, &req, NULL)) != 0 ) { + if(ret == EINTR) continue; + else { + if (ret == EINVAL) { + if (!einval_printed) { + einval_printed++; + 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++; + 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++; + 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 = 250 * USEC_PER_MS + ((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); + info("heartbeat randomness of %llu is too big for a tick of %llu - setting it to %llu", 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(next - 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; + error("heartbeat clock: woke up %llu 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; + error("heartbeat clock: woke up %llu 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(usec_t usec) { + // 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) + }; + +#ifdef __linux__ + while (clock_nanosleep(CLOCK_REALTIME, 0, &req, &rem) != 0) { +#else + while (nanosleep(&req, &rem) != 0) { +#endif + if (likely(errno == EINTR && (rem.tv_sec || rem.tv_nsec))) { + req = rem; + rem = (struct timespec){ 0, 0 }; + } + else { +#ifdef __linux__ + error("Cannot clock_nanosleep(CLOCK_REALTIME) for %llu microseconds.", usec); +#else + error("Cannot nanosleep() for %llu microseconds.", usec); +#endif + break; + } + } +} + +static inline collected_number uptime_from_boottime(void) { +#ifdef CLOCK_BOOTTIME_IS_AVAILABLE + return (collected_number)(now_boottime_usec() / USEC_PER_MS); +#else + 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)) { + error("/proc/uptime has no lines."); + return 0; + } + if(unlikely(procfile_linewords(read_proc_uptime_ff, 0) < 1)) { + 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); + info("Using now_boottime_usec() for uptime (dt is %lld ms)", delta); + use_boottime = 1; + } + else if(uptime_proc != 0) { + info("Using /proc/uptime for uptime (dt is %lld ms)", delta); + use_boottime = 0; + } + else { + 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; +} diff --git a/libnetdata/clocks/clocks.h b/libnetdata/clocks/clocks.h new file mode 100644 index 0000000..7738a2c --- /dev/null +++ b/libnetdata/clocks/clocks.h @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#ifndef NETDATA_CLOCKS_H +#define NETDATA_CLOCKS_H 1 + +#include "../libnetdata.h" + +#ifndef HAVE_STRUCT_TIMESPEC +struct timespec { + time_t tv_sec; /* seconds */ + long tv_nsec; /* nanoseconds */ +}; +#endif + +#ifndef HAVE_CLOCKID_T +typedef int clockid_t; +#endif + +typedef unsigned long long nsec_t; +typedef unsigned long long msec_t; +typedef unsigned long long usec_t; +typedef long long susec_t; + +typedef struct heartbeat { + usec_t realtime; + usec_t randomness; + size_t statistics_id; +} heartbeat_t; + +/* Linux value is as good as any other */ +#ifndef CLOCK_REALTIME +#define CLOCK_REALTIME 0 +#endif + +#ifndef CLOCK_MONOTONIC +/* fallback to CLOCK_REALTIME if not available */ +#define CLOCK_MONOTONIC CLOCK_REALTIME +#endif + +#ifndef CLOCK_BOOTTIME + +#ifdef CLOCK_UPTIME +/* CLOCK_BOOTTIME falls back to CLOCK_UPTIME on FreeBSD */ +#define CLOCK_BOOTTIME CLOCK_UPTIME +#else // CLOCK_UPTIME +/* CLOCK_BOOTTIME falls back to CLOCK_REALTIME */ +#define CLOCK_BOOTTIME CLOCK_REALTIME +#endif // CLOCK_UPTIME + +#else // CLOCK_BOOTTIME + +#ifdef HAVE_CLOCK_GETTIME +#define CLOCK_BOOTTIME_IS_AVAILABLE 1 // required for /proc/uptime +#endif // HAVE_CLOCK_GETTIME + +#endif // CLOCK_BOOTTIME + +#ifndef NSEC_PER_MSEC +#define NSEC_PER_MSEC 1000000ULL +#endif + +#ifndef NSEC_PER_SEC +#define NSEC_PER_SEC 1000000000ULL +#endif +#ifndef NSEC_PER_USEC +#define NSEC_PER_USEC 1000ULL +#endif + +#ifndef USEC_PER_SEC +#define USEC_PER_SEC 1000000ULL +#endif +#ifndef MSEC_PER_SEC +#define MSEC_PER_SEC 1000ULL +#endif + +#define USEC_PER_MS 1000ULL + +#ifndef HAVE_CLOCK_GETTIME +/* Fallback function for POSIX.1-2001 clock_gettime() function. + * + * We use a realtime clock from gettimeofday(), this will + * make systems without clock_gettime() support sensitive + * to time jumps or hibernation/suspend side effects. + */ +int clock_gettime(clockid_t clk_id, struct timespec *ts); +#endif + +/* + * Three clocks are available (cf. man 3 clock_gettime): + * + * REALTIME clock (i.e. wall-clock): + * This clock is affected by discontinuous jumps in the system time + * (e.g., if the system administrator manually changes the clock), and by the incremental adjustments performed by adjtime(3) and NTP. + * + * MONOTONIC clock + * Clock that cannot be set and represents monotonic time since some unspecified starting point. + * This clock is not affected by discontinuous jumps in the system time + * (e.g., if the system administrator manually changes the clock), but is affected by the incremental adjustments performed by adjtime(3) and NTP. + * If not available on the system, this clock falls back to REALTIME clock. + * + * BOOTTIME clock + * Identical to CLOCK_MONOTONIC, except it also includes any time that the system is suspended. + * This allows applications to get a suspend-aware monotonic clock without having to deal with the complications of CLOCK_REALTIME, + * which may have discontinuities if the time is changed using settimeofday(2). + * If not available on the system, this clock falls back to MONOTONIC clock. + * + * All now_*_timeval() functions fill the `struct timeval` with the time from the appropriate clock. + * Those functions return 0 on success, -1 else with errno set appropriately. + * + * All now_*_sec() functions return the time in seconds from the appropriate clock, or 0 on error. + * All now_*_usec() functions return the time in microseconds from the appropriate clock, or 0 on error. + * + */ +int now_realtime_timeval(struct timeval *tv); +time_t now_realtime_sec(void); +usec_t now_realtime_usec(void); + +int now_monotonic_timeval(struct timeval *tv); +time_t now_monotonic_sec(void); +usec_t now_monotonic_usec(void); +int now_monotonic_high_precision_timeval(struct timeval *tv); +time_t now_monotonic_high_precision_sec(void); +usec_t now_monotonic_high_precision_usec(void); + +int now_boottime_timeval(struct timeval *tv); +time_t now_boottime_sec(void); +usec_t now_boottime_usec(void); + +usec_t timeval_usec(struct timeval *tv); +msec_t timeval_msec(struct timeval *tv); + +usec_t dt_usec(struct timeval *now, struct timeval *old); +susec_t dt_usec_signed(struct timeval *now, struct timeval *old); + +void heartbeat_init(heartbeat_t *hb); + +/* Sleeps until next multiple of tick using monotonic clock. + * Returns elapsed time in microseconds since previous heartbeat + */ +usec_t heartbeat_next(heartbeat_t *hb, usec_t tick); + +void heartbeat_statistics(usec_t *min_ptr, usec_t *max_ptr, usec_t *average_ptr, size_t *count_ptr); + +void sleep_usec(usec_t usec); + +void clocks_init(void); + +// lower level functions - avoid using directly +time_t now_sec(clockid_t clk_id); +usec_t now_usec(clockid_t clk_id); +int now_timeval(clockid_t clk_id, struct timeval *tv); + +collected_number uptime_msec(char *filename); + +extern usec_t clock_monotonic_resolution; +extern usec_t clock_realtime_resolution; + +void sleep_to_absolute_time(usec_t usec); + +#endif /* NETDATA_CLOCKS_H */ |