High Resolution Timestamps for Profiling

configure.ac

@@ -1776,6 +1776,18 @@ if test "x${je_cv_mach_absolute_time}" = "xyes" ; then
   AC_DEFINE([JEMALLOC_HAVE_MACH_ABSOLUTE_TIME])
 fi
 
+dnl check for CLOCK_REALTIME (always should be available on Linux)
+JE_COMPILABLE([clock_gettime(CLOCK_REALTIME, ...)], [
+#include <time.h>
+], [
+	struct timespec ts;
+
+	clock_gettime(CLOCK_REALTIME, &ts);
+], [je_cv_clock_realtime])
+if test "x${je_cv_clock_realtime}" = "xyes" ; then
+  AC_DEFINE([JEMALLOC_HAVE_CLOCK_REALTIME])
+fi
+
 dnl Use syscall(2) (if available) by default.
 AC_ARG_ENABLE([syscall],
   [AS_HELP_STRING([--disable-syscall], [Disable use of syscall(2)])],

include/jemalloc/internal/jemalloc_internal_defs.h.in

@@ -100,6 +100,11 @@
  */
 #undef JEMALLOC_HAVE_MACH_ABSOLUTE_TIME
 
+/*
+ * Defined if clock_gettime(CLOCK_REALTIME, ...) is available.
+ */
+#undef JEMALLOC_HAVE_CLOCK_REALTIME
+
 /*
  * Defined if _malloc_thread_cleanup() exists.  At least in the case of
  * FreeBSD, pthread_key_create() allocates, which if used during malloc

include/jemalloc/internal/jemalloc_internal_externs.h

@@ -3,6 +3,7 @@
 
 #include "jemalloc/internal/atomic.h"
 #include "jemalloc/internal/tsd_types.h"
+#include "jemalloc/internal/nstime.h"
 
 /* TSD checks this to set thread local slow state accordingly. */
 extern bool malloc_slow;

include/jemalloc/internal/jemalloc_preamble.h.in

@@ -209,5 +209,12 @@ static const bool have_background_thread =
     false
 #endif
     ;
+static const bool config_high_res_timer =
+#ifdef JEMALLOC_HAVE_CLOCK_REALTIME
+    true
+#else
+    false
+#endif
+    ;
 
 #endif /* JEMALLOC_PREAMBLE_H */

include/jemalloc/internal/nstime.h

@@ -30,10 +30,23 @@ uint64_t nstime_divide(const nstime_t *time, const nstime_t *divisor);
 typedef bool (nstime_monotonic_t)(void);
 extern nstime_monotonic_t *JET_MUTABLE nstime_monotonic;
 
-typedef bool (nstime_update_t)(nstime_t *);
+typedef void (nstime_update_t)(nstime_t *);
 extern nstime_update_t *JET_MUTABLE nstime_update;
 
-bool nstime_init_update(nstime_t *time);
+typedef void (nstime_prof_update_t)(nstime_t *);
+extern nstime_prof_update_t *JET_MUTABLE nstime_prof_update;
+
+void nstime_init_update(nstime_t *time);
+void nstime_prof_init_update(nstime_t *time);
+
+enum prof_time_res_e {
+	prof_time_res_default = 0,
+	prof_time_res_high = 1
+};
+typedef enum prof_time_res_e prof_time_res_t;
+
+extern prof_time_res_t opt_prof_time_res;
+extern const char *prof_time_res_mode_names[];
 
 JEMALLOC_ALWAYS_INLINE void
 nstime_init_zero(nstime_t *time) {

src/ctl.c

@@ -129,6 +129,7 @@ CTL_PROTO(opt_prof_leak)
 CTL_PROTO(opt_prof_accum)
 CTL_PROTO(opt_prof_recent_alloc_max)
 CTL_PROTO(opt_prof_experimental_use_sys_thread_name)
+CTL_PROTO(opt_prof_time_res)
 CTL_PROTO(opt_zero_realloc)
 CTL_PROTO(tcache_create)
 CTL_PROTO(tcache_flush)
@@ -385,7 +386,8 @@ static const ctl_named_node_t opt_node[] = {
 	{NAME("prof_recent_alloc_max"), CTL(opt_prof_recent_alloc_max)},
 	{NAME("prof_experimental_use_sys_thread_name"),
 	    CTL(opt_prof_experimental_use_sys_thread_name)},
-	{NAME("zero_realloc"),	CTL(opt_zero_realloc)}
+	{NAME("zero_realloc"),	CTL(opt_zero_realloc)},
+	{NAME("prof_time_resolution"),	CTL(opt_prof_time_res)}
 };
 
 static const ctl_named_node_t	tcache_node[] = {
@@ -1853,6 +1855,8 @@ CTL_RO_NL_CGEN(config_prof, opt_prof_recent_alloc_max,
     opt_prof_recent_alloc_max, ssize_t)
 CTL_RO_NL_CGEN(config_prof, opt_prof_experimental_use_sys_thread_name,
     opt_prof_experimental_use_sys_thread_name, bool)
+CTL_RO_NL_CGEN(config_prof, opt_prof_time_res,
+    prof_time_res_mode_names[opt_prof_time_res], const char *)
 CTL_RO_NL_GEN(opt_zero_realloc,
     zero_realloc_mode_names[opt_zero_realloc_action], const char *)
 

src/jemalloc.c

@@ -14,6 +14,7 @@
 #include "jemalloc/internal/log.h"
 #include "jemalloc/internal/malloc_io.h"
 #include "jemalloc/internal/mutex.h"
+#include "jemalloc/internal/nstime.h"
 #include "jemalloc/internal/rtree.h"
 #include "jemalloc/internal/safety_check.h"
 #include "jemalloc/internal/sc.h"
@@ -1497,6 +1498,26 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
 				CONF_HANDLE_BOOL(
 				    opt_prof_experimental_use_sys_thread_name,
 				    "prof_experimental_use_sys_thread_name")
+				if (CONF_MATCH("prof_time_resolution")) {
+					if (CONF_MATCH_VALUE("default")) {
+						opt_prof_time_res =
+						    prof_time_res_default;
+					} else if (CONF_MATCH_VALUE("high")) {
+						if (!config_high_res_timer) {
+							CONF_ERROR(
+							    "No high resolution"
+							    " timer support",
+							    k, klen, v, vlen);
+						} else {
+							opt_prof_time_res =
+							    prof_time_res_high;
+						}
+					} else {
+						CONF_ERROR("Invalid conf value",
+						    k, klen, v, vlen);
+					}
+				}
+				CONF_CONTINUE;
 			}
 			if (config_log) {
 				if (CONF_MATCH("log")) {

src/large.c

@@ -305,7 +305,7 @@ large_prof_tctx_reset(edata_t *edata) {
 void
 large_prof_info_set(edata_t *edata, prof_tctx_t *tctx) {
 	nstime_t t;
-	nstime_init_update(&t);
+	nstime_prof_init_update(&t);
 	edata_prof_alloc_time_set(edata, &t);
 	edata_prof_recent_alloc_init(edata);
 	large_prof_tctx_set(edata, tctx);

src/nstime.c

@@ -152,25 +152,65 @@ nstime_monotonic_impl(void) {
 }
 nstime_monotonic_t *JET_MUTABLE nstime_monotonic = nstime_monotonic_impl;
 
-static bool
+prof_time_res_t opt_prof_time_res =
+	prof_time_res_default;
+
+const char *prof_time_res_mode_names[] = {
+	"default",
+	"high",
+};
+
+
+static void
+nstime_get_realtime(nstime_t *time) {
+#if defined(JEMALLOC_HAVE_CLOCK_REALTIME) && !defined(_WIN32)
+	struct timespec ts;
+
+	clock_gettime(CLOCK_REALTIME, &ts);
+	nstime_init2(time, ts.tv_sec, ts.tv_nsec);
+#else
+	unreachable();
+#endif
+}
+
+static void
+nstime_prof_update_impl(nstime_t *time) {
+	nstime_t old_time;
+
+	nstime_copy(&old_time, time);
+
+	if (opt_prof_time_res == prof_time_res_high) {
+		nstime_get_realtime(time);
+	} else {
+		nstime_get(time);
+	}
+}
+nstime_prof_update_t *JET_MUTABLE nstime_prof_update = nstime_prof_update_impl;
+
+static void
 nstime_update_impl(nstime_t *time) {
 	nstime_t old_time;
 
 	nstime_copy(&old_time, time);
-	nstime_get(time);
+  nstime_get(time);
 
 	/* Handle non-monotonic clocks. */
 	if (unlikely(nstime_compare(&old_time, time) > 0)) {
 		nstime_copy(time, &old_time);
-		return true;
 	}
-
-	return false;
 }
 nstime_update_t *JET_MUTABLE nstime_update = nstime_update_impl;
 
-bool
+void
 nstime_init_update(nstime_t *time) {
 	nstime_init_zero(time);
-	return nstime_update(time);
+	nstime_update(time);
 }
+
+void
+nstime_prof_init_update(nstime_t *time) {
+	nstime_init_zero(time);
+	nstime_prof_update(time);
+}
+
+

src/prof_log.c

@@ -235,7 +235,7 @@ prof_try_log(tsd_t *tsd, size_t usize, prof_info_t *prof_info) {
 
 	nstime_t alloc_time = prof_info->alloc_time;
 	nstime_t free_time;
-	nstime_init_update(&free_time);
+	nstime_prof_init_update(&free_time);
 
 	size_t sz = sizeof(prof_alloc_node_t);
 	prof_alloc_node_t *new_node = (prof_alloc_node_t *)
@@ -572,6 +572,11 @@ prof_log_emit_metadata(emitter_t *emitter) {
 	emitter_json_kv(emitter, "lg_sample_rate",
 	    emitter_type_int, &lg_prof_sample);
 
+  const char *res_type =
+    prof_time_res_mode_names[opt_prof_time_res];
+  emitter_json_kv(emitter, "prof_time_resolution",
+      emitter_type_string, &res_type);
+
 	int pid = prof_getpid();
 	emitter_json_kv(emitter, "pid", emitter_type_int, &pid);
 

src/prof_recent.c

@@ -219,7 +219,7 @@ prof_recent_alloc_reset(tsd_t *tsd, edata_t *edata) {
 		assert(nstime_equals_zero(&recent->dalloc_time));
 		assert(recent->dalloc_tctx == NULL);
 		if (dalloc_tctx != NULL) {
-			nstime_update(&recent->dalloc_time);
+			nstime_prof_update(&recent->dalloc_time);
 			recent->dalloc_tctx = dalloc_tctx;
 			dalloc_tctx = NULL;
 		}

test/unit/arena_decay.c

@@ -26,13 +26,12 @@ nstime_monotonic_mock(void) {
 	return monotonic_mock;
 }
 
-static bool
+static void
 nstime_update_mock(nstime_t *time) {
 	nupdates_mock++;
 	if (monotonic_mock) {
 		nstime_copy(time, &time_mock);
 	}
-	return !monotonic_mock;
 }
 
 static unsigned

test/unit/nstime.c

@@ -206,28 +206,6 @@ TEST_BEGIN(test_nstime_monotonic) {
 }
 TEST_END
 
-TEST_BEGIN(test_nstime_update) {
-	nstime_t nst;
-
-	expect_false(nstime_init_update(&nst), "Basic time update failed.");
-
-	/* Only Rip Van Winkle sleeps this long. */
-	{
-		nstime_t addend;
-		nstime_init2(&addend, 631152000, 0);
-		nstime_add(&nst, &addend);
-	}
-	{
-		nstime_t nst0;
-		nstime_copy(&nst0, &nst);
-		expect_true(nstime_update(&nst),
-		    "Update should detect time roll-back.");
-		expect_d_eq(nstime_compare(&nst, &nst0), 0,
-		    "Time should not have been modified");
-	}
-}
-TEST_END
-
 int
 main(void) {
 	return test(
@@ -242,6 +220,5 @@ main(void) {
 	    test_nstime_imultiply,
 	    test_nstime_idivide,
 	    test_nstime_divide,
-	    test_nstime_monotonic,
-	    test_nstime_update);
+	    test_nstime_monotonic);
 }