Request reviewing patch for bug8006942

[liang xie]

Hi,

here is an updated patch for bug8006942, please help to review, thanks in
advance.

diff -r 8389681cd7b1 src/os/linux/vm/os_linux.cpp
--- a/src/os/linux/vm/os_linux.cpp    Tue Nov 15 16:44:09 2011 -0800
+++ b/src/os/linux/vm/os_linux.cpp    Fri Feb 01 20:18:36 2013 +0800
@@ -149,6 +149,7 @@
 static sigset_t check_signal_done;
 static bool check_signals = true;;

+static bool support_clock_monotonic_raw = false;
 static pid_t _initial_pid = 0;

 /* Signal number used to suspend/resume a thread */
@@ -1388,9 +1389,14 @@
       // won't be a problem.
       struct timespec res;
       struct timespec tp;
-      if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
-          clock_gettime_func(CLOCK_MONOTONIC, &tp)  == 0) {
-        // yes, monotonic clock is supported
+      if (clock_getres_func (CLOCK_MONOTONIC_RAW, &res) == 0 &&
+          clock_gettime_func(CLOCK_MONOTONIC_RAW, &tp)  == 0) {
+        // raw monotonic clock is supported
+        _clock_gettime = clock_gettime_func;
+        support_clock_monotonic_raw = true;
+      } else if (clock_getres_func (CLOCK_MONOTONIC, &res) == 0 &&
+          clock_gettime_func(CLOCK_MONOTONIC, &tp) {
+        // monotonic clock is supported
         _clock_gettime = clock_gettime_func;
       } else {
         // close librt if there is no monotonic clock
@@ -1444,7 +1450,11 @@
 jlong os::javaTimeNanos() {
   if (Linux::supports_monotonic_clock()) {
     struct timespec tp;
-    int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
+    if (support_clock_monotonic_raw) {
+      int status = Linux::clock_gettime(CLOCK_MONOTONIC_RAW, &tp);
+    } else {
+      int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
+    }
     assert(status == 0, "gettime error");
     jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) +
jlong(tp.tv_nsec);
     return result;


Best Regards,
Liang
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