From ff4eedb54fbd3d1f757a07681d1318be47512bb2 Mon Sep 17 00:00:00 2001
From: Arnaud Giersch <arnaud.giersch@iut-bm.univ-fcomte.fr>
Date: Thu, 1 Mar 2012 09:44:06 +0100
Subject: [PATCH] Use clock_gettime for a better resolution in timer.h.

---
 Makefile |  2 +-
 timer.h  | 82 +++++++++++++++++++++-----------------------------------
 2 files changed, 31 insertions(+), 53 deletions(-)

diff --git a/Makefile b/Makefile
index 59afd30..7ec6c5d 100644
--- a/Makefile
+++ b/Makefile
@@ -23,7 +23,7 @@ LDFLAGS += -L $(SIMGRID_INSTALL_DIR)/lib
 LDFLAGS += -Wl,-rpath,$(SIMGRID_INSTALL_DIR)/lib
 
 LINK.o = $(CXX) $(CXXFLAGS) $(LDFLAGS) $(TARGET_ARCH)
-LDLIBS := -lsimgrid
+LDLIBS := -lsimgrid -lrt
 
 MAKEDEPEND.FLAGS =  $(CPPFLAGS) -MM -MG -MF $@ $<
 MAKEDEPEND.C = $(CC) $(CFLAGS) $(MAKEDEPEND.FLAGS)
diff --git a/timer.h b/timer.h
index 7ddc3ee..52502a1 100644
--- a/timer.h
+++ b/timer.h
@@ -1,51 +1,31 @@
 #ifndef TIMER_H
 #define TIMER_H
 
-#include <sys/time.h>
-#include <sys/resource.h>
-
-#ifdef _BSD_SOURCE
-#  define HAVE_TIMERADD
-#  define HAVE_TIMERSUB
-#  define HAVE_TIMERCLEAR
-#else
-#  warning _BSD_SOURCE not defined
-#  undef HAVE_TIMERADD
-#  undef HAVE_TIMERSUB
-#  undef HAVE_TIMERCLEAR
-#endif
+#include <ctime>
 
 inline
-struct timeval operator+(const struct timeval& a, const struct timeval& b)
+struct timespec operator+(const struct timespec& a, const struct timespec& b)
 {
-    struct timeval result;
-#ifdef HAVE_TIMERADD
-    timeradd(&a, &b, &result);
-#else
+    struct timespec result;
     result.tv_sec = a.tv_sec + b.tv_sec;
-    result.tv_usec = a.tv_usec + b.tv_usec;
-    if (result.tv_usec >= 1000000) {
+    result.tv_nsec = a.tv_nsec + b.tv_nsec;
+    if (result.tv_nsec >= 1000000000L) {
         ++result.tv_sec;
-        result.tv_usec -= 1000000;
+        result.tv_nsec -= 1000000000L;
     }
-#endif
     return result;
 }
 
 inline
-struct timeval operator-(const struct timeval& a, const struct timeval& b)
+struct timespec operator-(const struct timespec& a, const struct timespec& b)
 {
-    struct timeval result;
-#ifdef HAVE_TIMERSUB
-    timersub(&a, &b, &result);
-#else
+    struct timespec result;
     result.tv_sec = a.tv_sec - b.tv_sec;
-    result.tv_usec = a.tv_usec - b.tv_usec;
-    if (result.tv_usec < 0) {
+    result.tv_nsec = a.tv_nsec - b.tv_nsec;
+    if (result.tv_nsec < 0) {
         --result.tv_sec;
-        result.tv_usec += 1000000;
+        result.tv_nsec += 1000000000L;
     }
-#endif
     return result;
 }
 
@@ -60,19 +40,19 @@ public:
     void start();
     void stop();
 
-    struct timeval tv_duration() const;
+    struct timespec tv_duration() const;
     double duration() const;
 
 private:
     clock_type clk;
-    struct timeval before;
-    struct timeval after;
-    struct timeval difference;
+    struct timespec before;
+    struct timespec after;
+    struct timespec difference;
 
-    void get_time(struct timeval& tv);
+    void get_time(struct timespec& tv);
 
-    static void tv_clear(struct timeval& a);
-    static double timertod(const struct timeval& a);
+    static void tv_clear(struct timespec& a);
+    static double timertod(const struct timespec& a);
 };
 
 inline
@@ -108,7 +88,7 @@ void timestamp::stop()
 }
 
 inline
-struct timeval timestamp::tv_duration() const
+struct timespec timestamp::tv_duration() const
 {
     return difference;
 }
@@ -120,36 +100,34 @@ double timestamp::duration() const
 }
 
 inline
-void timestamp::get_time(struct timeval& tv)
+void timestamp::get_time(struct timespec& tv)
 {
     switch (clk) {
     case cpu_time: {
-        struct rusage usage;
-        getrusage(RUSAGE_SELF, &usage);
-        tv = usage.ru_utime + usage.ru_stime;
+        clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &tv);
         break;
     }
     case wallclock_time:
-        gettimeofday(&tv, NULL);
+#ifdef CLOCK_MONOTONIC_RAW
+        clock_gettime(CLOCK_MONOTONIC_RAW, &tv);
+#else
+        clock_gettime(CLOCK_MONOTONIC, &tv);
+#endif
         break;
     }
 }
 
 inline
-void timestamp::tv_clear(struct timeval& a)
+void timestamp::tv_clear(struct timespec& a)
 {
-#ifdef HAVE_TIMERCLEAR
-    timerclear(&a);
-#else
     a.tv_sec = 0;
-    a.tv_usec = 0;
-#endif
+    a.tv_nsec = 0;
 }
 
 inline
-double timestamp::timertod(const struct timeval& a)
+double timestamp::timertod(const struct timespec& a)
 {
-    return a.tv_sec + a.tv_usec / 1e6;
+    return a.tv_sec + a.tv_nsec / 1e9;
 }
 
 #endif // !TIMER_H
-- 
2.39.5