* gc.c (getrusage_time): uses clock_gettime() with

  CLOCK_PROCESS_CPUTIME_ID when available, which provides a 1ns
  precision on linux. [ruby-core:50495] [Bug #7500]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38214 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 14 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f0c11cdcd7..b54cc20668 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Dec  5 23:50:23 2012  Narihiro Nakamura  <authornari@gmail.com>
+
+	* gc.c (getrusage_time): uses clock_gettime() with
+	  CLOCK_PROCESS_CPUTIME_ID when available, which provides a 1ns
+	  precision on linux. [ruby-core:50495] [Bug #7500]
+
 Wed Dec  5 22:46:02 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* vm.c (rb_vm_make_proc): save the proc made from the given block so
diff --git a/gc.c b/gc.c
index dfbc82b7b9..beaadddb54 100644
--- a/gc.c
+++ b/gc.c
@@ -3853,7 +3853,14 @@ static inline void gc_prof_set_heap_info(rb_objspace_t *, gc_profile_record *);
 static double
 getrusage_time(void)
 {
-#ifdef RUSAGE_SELF
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_PROCESS_CPUTIME_ID)
+    struct timespec ts;
+
+    if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == 0) {
+        return ts.tv_sec + ts.tv_nsec * 1e-9;
+    }
+    return 0.0;
+#elif defined RUSAGE_SELF
     struct rusage usage;
     struct timeval time;
     getrusage(RUSAGE_SELF, &usage);