--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Tue Feb 14 08:21:08 2012 -0500
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Wed Jan 18 09:50:16 2012 -0800
@@ -6092,7 +6092,11 @@
   _inter_sweep_timer.reset();
   _inter_sweep_timer.start();
 
-  update_time_of_last_gc(os::javaTimeMillis());
+  // We need to use a monotonically non-deccreasing time in ms
+  // or we will see time-warp warnings and os::javaTimeMillis()
+  // does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+  update_time_of_last_gc(now);
 
   // NOTE on abstract state transitions:
   // Mutators allocate-live and/or mark the mod-union table dirty