Trivial patch about "Use CLOCK_MONOTONIC_RAW if available"

[liang xie]

Hi,

I'm not familiar hotspot dev flow and i don't know how to make a webcr:)
please feel free to
move it to the correct list if wrong.

"CLOCK_MONOTONIC_RAW" is available from 2.6.28+, it's a better choice while
ntp
slew happened againt CLOCK_MONOTONIC_RAW. This's important for some
applications,
e.g.  zookeeper.  Please see zookeeper--1616 for details.


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 Jan 25 15:14:55 2013 +0800
@@ -1444,7 +1444,11 @@
 jlong os::javaTimeNanos() {
   if (Linux::supports_monotonic_clock()) {
     struct timespec tp;
+  #ifdef CLOCK_MONOTONIC_RAW
+    int status = Linux::clock_gettime(CLOCK_MONOTONIC_RAW, &tp);
+  #else
     int status = Linux::clock_gettime(CLOCK_MONOTONIC, &tp);
+  #endif
     assert(status == 0, "gettime error");
     jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) +
jlong(tp.tv_nsec);
     return result;