From: Pierre-Marc Fournier <pierre-marc.fournier@polymtl.ca>
Date: Wed, 26 May 2010 16:32:36 +0000 (-0400)
Subject: Replace gettimeofday() with clock_gettime(CLOCK_MONOTONIC,...)
X-Git-Tag: v0.5~16
X-Git-Url: http://git.lttng.org/?p=ust.git;a=commitdiff_plain;h=ca4525b556680256149ead3746b566103e043d8e

Replace gettimeofday() with clock_gettime(CLOCK_MONOTONIC,...)

Contributed by Nils Carlson.
---

diff --git a/include/ust/clock.h b/include/ust/clock.h
index d4b6a9d..cb8a663 100644
--- a/include/ust/clock.h
+++ b/include/ust/clock.h
@@ -18,6 +18,7 @@
 #ifndef UST_CLOCK_H
 #define UST_CLOCK_H
 
+#include <time.h>
 #include <sys/time.h>
 #include <ust/kcompat/kcompat.h>
 
@@ -34,6 +35,9 @@
    For merging traces with the kernel, a time source compatible with that of
    the kernel is necessary.
 
+   Instead of gettimeofday(), we are now using clock_gettime for better
+   precision and monotonicity.
+
 */
 
 #define TRACE_CLOCK_GENERIC
@@ -41,13 +45,13 @@
 
 static __inline__ u64 trace_clock_read64(void)
 {
-	struct timeval tv;
+	struct timespec ts;
 	u64 retval;
 
-	gettimeofday(&tv, NULL);
-	retval = tv.tv_sec;
-	retval *= 1000000;
-	retval += tv.tv_usec;
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	retval = ts.tv_sec;
+	retval *= 1000000000;
+	retval += ts.tv_nsec;
 
 	return retval;
 }
@@ -104,7 +108,7 @@ static __inline__ u64 trace_clock_read64(void)
 
 static __inline__ u64 trace_clock_frequency(void)
 {
-	return 1000000LL;
+	return 1000000000LL;
 }
 
 static __inline__ u32 trace_clock_freq_scale(void)
diff --git a/libust/Makefile.am b/libust/Makefile.am
index 2de5857..e357ad1 100644
--- a/libust/Makefile.am
+++ b/libust/Makefile.am
@@ -27,6 +27,7 @@ libust_la_LDFLAGS = -no-undefined -version-info 0:0:0
 
 libust_la_LIBADD = \
 	-lpthread \
+	-lrt \
 	$(top_builddir)/snprintf/libustsnprintf.la \
 	$(top_builddir)/libustcomm/libustcomm.la