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-rw-r--r--libnetdata/clocks/clocks.c301
-rw-r--r--libnetdata/clocks/clocks.h41
2 files changed, 232 insertions, 110 deletions
diff --git a/libnetdata/clocks/clocks.c b/libnetdata/clocks/clocks.c
index 4ec5fa98b..f0e17b232 100644
--- a/libnetdata/clocks/clocks.c
+++ b/libnetdata/clocks/clocks.c
@@ -2,8 +2,13 @@
#include "../libnetdata.h"
-static int clock_boottime_valid = 1;
-static int clock_monotonic_coarse_valid = 1;
+// 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, struct timespec *ts) {
@@ -18,19 +23,60 @@ inline int clock_gettime(clockid_t clk_id, struct timespec *ts) {
}
#endif
-void test_clock_boottime(void) {
+// 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_valid = 0;
+ clock_boottime_to_use = clock_monotonic_to_use;
+ else
+ clock_boottime_to_use = CLOCK_BOOTTIME;
}
-void test_clock_monotonic_coarse(void) {
+static usec_t get_clock_resolution(clockid_t clock) {
struct timespec ts;
- if(clock_gettime(CLOCK_MONOTONIC_COARSE, &ts) == -1 && errno == EINVAL)
- clock_monotonic_coarse_valid = 0;
+ 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;
}
-static inline time_t now_sec(clockid_t clk_id) {
+inline time_t now_sec(clockid_t clk_id) {
struct timespec ts;
if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
error("clock_gettime(%d, &timespec) failed.", clk_id);
@@ -39,7 +85,7 @@ static inline time_t now_sec(clockid_t clk_id) {
return ts.tv_sec;
}
-static inline usec_t now_usec(clockid_t clk_id) {
+inline usec_t now_usec(clockid_t clk_id) {
struct timespec ts;
if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
error("clock_gettime(%d, &timespec) failed.", clk_id);
@@ -48,7 +94,7 @@ static inline usec_t now_usec(clockid_t clk_id) {
return (usec_t)ts.tv_sec * USEC_PER_SEC + (ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC;
}
-static inline int now_timeval(clockid_t clk_id, struct timeval *tv) {
+inline int now_timeval(clockid_t clk_id, struct timeval *tv) {
struct timespec ts;
if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
@@ -76,15 +122,15 @@ inline int now_realtime_timeval(struct timeval *tv) {
}
inline time_t now_monotonic_sec(void) {
- return now_sec(likely(clock_monotonic_coarse_valid) ? CLOCK_MONOTONIC_COARSE : CLOCK_MONOTONIC);
+ return now_sec(clock_monotonic_to_use);
}
inline usec_t now_monotonic_usec(void) {
- return now_usec(likely(clock_monotonic_coarse_valid) ? CLOCK_MONOTONIC_COARSE : CLOCK_MONOTONIC);
+ return now_usec(clock_monotonic_to_use);
}
inline int now_monotonic_timeval(struct timeval *tv) {
- return now_timeval(likely(clock_monotonic_coarse_valid) ? CLOCK_MONOTONIC_COARSE : CLOCK_MONOTONIC, tv);
+ return now_timeval(clock_monotonic_to_use, tv);
}
inline time_t now_monotonic_high_precision_sec(void) {
@@ -100,19 +146,15 @@ inline int now_monotonic_high_precision_timeval(struct timeval *tv) {
}
inline time_t now_boottime_sec(void) {
- return now_sec(likely(clock_boottime_valid) ? CLOCK_BOOTTIME :
- likely(clock_monotonic_coarse_valid) ? CLOCK_MONOTONIC_COARSE : CLOCK_MONOTONIC);
+ return now_sec(clock_boottime_to_use);
}
inline usec_t now_boottime_usec(void) {
- return now_usec(likely(clock_boottime_valid) ? CLOCK_BOOTTIME :
- likely(clock_monotonic_coarse_valid) ? CLOCK_MONOTONIC_COARSE : CLOCK_MONOTONIC);
+ return now_usec(clock_boottime_to_use);
}
inline int now_boottime_timeval(struct timeval *tv) {
- return now_timeval(likely(clock_boottime_valid) ? CLOCK_BOOTTIME :
- likely(clock_monotonic_coarse_valid) ? CLOCK_MONOTONIC_COARSE : CLOCK_MONOTONIC,
- tv);
+ return now_timeval(clock_boottime_to_use, tv);
}
inline usec_t timeval_usec(struct timeval *tv) {
@@ -137,9 +179,113 @@ inline usec_t dt_usec(struct timeval *now, struct timeval *old) {
return (ts1 > ts2) ? (ts1 - ts2) : (ts2 - ts1);
}
-inline void heartbeat_init(heartbeat_t *hb)
-{
- hb->monotonic = hb->realtime = 0ULL;
+#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 = %ld, tv_nsec = %ld",
+ clock,
+ 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 = %ld, tv_nsec = %ld",
+ clock,
+ req.tv_sec,
+ req.tv_nsec);
+ }
+ } else {
+ if (!eunknown_printed) {
+ eunknown_printed++;
+ error(
+ "Unknown return value %d from clock_nanosleep(): clockid = %d, tv_sec = %ld, tv_nsec = %ld",
+ ret,
+ clock,
+ 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
@@ -147,96 +293,81 @@ inline void heartbeat_init(heartbeat_t *hb)
// it returns the dt using the realtime clock
usec_t heartbeat_next(heartbeat_t *hb, usec_t tick) {
- heartbeat_t now;
- now.monotonic = now_monotonic_usec();
- now.realtime = now_realtime_usec();
-
- usec_t next_monotonic = now.monotonic - (now.monotonic % tick) + tick;
-
- while(now.monotonic < next_monotonic) {
- sleep_usec(next_monotonic - now.monotonic);
- now.monotonic = now_monotonic_usec();
- now.realtime = now_realtime_usec();
+ 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;
}
- if(likely(hb->realtime != 0ULL)) {
- usec_t dt_monotonic = now.monotonic - hb->monotonic;
- usec_t dt_realtime = now.realtime - hb->realtime;
+ usec_t dt;
+ usec_t now = now_realtime_usec();
+ usec_t next = now - (now % tick) + tick + hb->randomness;
- hb->monotonic = now.monotonic;
- hb->realtime = now.realtime;
+ // align the next time we want to the clock resolution
+ if(next % clock_realtime_resolution)
+ next = next - (next % clock_realtime_resolution) + clock_realtime_resolution;
- if(unlikely(dt_monotonic >= tick + tick / 2)) {
- errno = 0;
- error("heartbeat missed %llu monotonic microseconds", dt_monotonic - tick);
- }
+ // 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;
- return dt_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++;
}
- else {
- hb->monotonic = now.monotonic;
- hb->realtime = now.realtime;
- return 0ULL;
+
+ 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);
}
-}
-// returned the elapsed time, since the last heartbeat
-// using the monotonic clock
+ if(unlikely(!hb->realtime)) {
+ // the first time return zero
+ dt = 0;
+ }
-inline usec_t heartbeat_monotonic_dt_to_now_usec(heartbeat_t *hb) {
- if(!hb || !hb->monotonic) return 0ULL;
- return now_monotonic_usec() - hb->monotonic;
+ hb->realtime = now;
+ return dt;
}
-int sleep_usec(usec_t usec) {
-
-#ifndef NETDATA_WITH_USLEEP
+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, req = {
- .tv_sec = (time_t) (usec / 1000000),
- .tv_nsec = (suseconds_t) ((usec % 1000000) * 1000)
+ .tv_sec = (time_t) (usec / USEC_PER_SEC),
+ .tv_nsec = (suseconds_t) ((usec % USEC_PER_SEC) * NSEC_PER_USEC)
};
- while (nanosleep(&req, &rem) == -1) {
+#ifdef __linux__
+ while ((errno = clock_nanosleep(CLOCK_REALTIME, 0, &req, &rem)) != 0) {
+#else
+ while ((errno = nanosleep(&req, &rem)) != 0) {
+#endif
if (likely(errno == EINTR)) {
- debug(D_SYSTEM, "nanosleep() interrupted (while sleeping for %llu microseconds).", usec);
req.tv_sec = rem.tv_sec;
req.tv_nsec = rem.tv_nsec;
} else {
+#ifdef __linux__
+ error("Cannot clock_nanosleep(CLOCK_REALTIME) for %llu microseconds.", usec);
+#else
error("Cannot nanosleep() for %llu microseconds.", usec);
+#endif
break;
}
}
-
- return 0;
-#else
- int ret = usleep(usec);
- if(unlikely(ret == -1 && errno == EINVAL)) {
- // on certain systems, usec has to be up to 999999
- if(usec > 999999) {
- int counter = usec / 999999;
- while(counter--)
- usleep(999999);
-
- usleep(usec % 999999);
- }
- else {
- error("Cannot usleep() for %llu microseconds.", usec);
- return ret;
- }
- }
-
- if(ret != 0)
- error("usleep() failed for %llu microseconds.", usec);
-
- return ret;
-#endif
}
static inline collected_number uptime_from_boottime(void) {
#ifdef CLOCK_BOOTTIME_IS_AVAILABLE
- return now_boottime_usec() / 1000;
+ return (collected_number)(now_boottime_usec() / USEC_PER_MS);
#else
error("uptime cannot be read from CLOCK_BOOTTIME on this system.");
return 0;
diff --git a/libnetdata/clocks/clocks.h b/libnetdata/clocks/clocks.h
index d3475df6a..53c036ece 100644
--- a/libnetdata/clocks/clocks.h
+++ b/libnetdata/clocks/clocks.h
@@ -22,8 +22,9 @@ typedef unsigned long long usec_t;
typedef long long susec_t;
typedef struct heartbeat {
- usec_t monotonic;
usec_t realtime;
+ usec_t randomness;
+ size_t statistics_id;
} heartbeat_t;
/* Linux value is as good as any other */
@@ -36,20 +37,14 @@ typedef struct heartbeat {
#define CLOCK_MONOTONIC CLOCK_REALTIME
#endif
-/* Prefer CLOCK_MONOTONIC_COARSE where available to reduce overhead. It has the same semantics as CLOCK_MONOTONIC */
-#ifndef CLOCK_MONOTONIC_COARSE
-/* fallback to CLOCK_MONOTONIC if not available */
-#define CLOCK_MONOTONIC_COARSE CLOCK_MONOTONIC
-#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_MONOTONIC */
-#define CLOCK_BOOTTIME CLOCK_MONOTONIC_COARSE
+/* CLOCK_BOOTTIME falls back to CLOCK_REALTIME */
+#define CLOCK_BOOTTIME CLOCK_REALTIME
#endif // CLOCK_UPTIME
#else // CLOCK_BOOTTIME
@@ -115,8 +110,6 @@ extern int clock_gettime(clockid_t clk_id, struct timespec *ts);
* 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.
*
- * Most functions will attempt to use CLOCK_MONOTONIC_COARSE if available to reduce contention overhead and improve
- * performance scaling. If high precision is required please use one of the available now_*_high_precision_* functions.
*/
extern int now_realtime_timeval(struct timeval *tv);
extern time_t now_realtime_sec(void);
@@ -133,7 +126,6 @@ extern int now_boottime_timeval(struct timeval *tv);
extern time_t now_boottime_sec(void);
extern usec_t now_boottime_usec(void);
-
extern usec_t timeval_usec(struct timeval *tv);
extern msec_t timeval_msec(struct timeval *tv);
@@ -147,23 +139,22 @@ extern void heartbeat_init(heartbeat_t *hb);
*/
extern usec_t heartbeat_next(heartbeat_t *hb, usec_t tick);
-/* Returns elapsed time in microseconds since last heartbeat */
-extern usec_t heartbeat_monotonic_dt_to_now_usec(heartbeat_t *hb);
+extern void heartbeat_statistics(usec_t *min_ptr, usec_t *max_ptr, usec_t *average_ptr, size_t *count_ptr);
-extern int sleep_usec(usec_t usec);
+extern void sleep_usec(usec_t usec);
-/*
- * 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.
- */
-void test_clock_boottime(void);
+extern void clocks_init(void);
-/*
- * When running a binary with CLOCK_MONOTONIC_COARSE defined on a system with a linux kernel older than Linux 2.6.32 the
- * clock_gettime(2) system call fails with EINVAL. In that case it must fall-back to CLOCK_MONOTONIC.
- */
-void test_clock_monotonic_coarse(void);
+// lower level functions - avoid using directly
+extern time_t now_sec(clockid_t clk_id);
+extern usec_t now_usec(clockid_t clk_id);
+extern int now_timeval(clockid_t clk_id, struct timeval *tv);
extern collected_number uptime_msec(char *filename);
+extern usec_t clock_monotonic_resolution;
+extern usec_t clock_realtime_resolution;
+
+extern void sleep_to_absolute_time(usec_t usec);
+
#endif /* NETDATA_CLOCKS_H */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-04 07:17:13 +0000