JDK-6649622 : HotSpot Biased locking needs tuning on latest CPUs
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 6u4p
  • Priority: P2
  • Status: Resolved
  • Resolution: Fixed
  • OS: solaris_nevada
  • CPU: x86
  • Submitted: 2008-01-11
  • Updated: 2011-02-17
  • Resolved: 2008-11-19
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JDK 6 JDK 7 Other
6u14Fixed 7Fixed hs14Fixed
HotSpot Biased Locking needs tunign on latest CPUs.

-see comments for details-

EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/b6cfd754403d

EVALUATION Can put pushed to hs13 with AggressiveOpts, perhaps hs14 without.

SUGGESTED FIX Add to set_aggressive_opts_flags() in arguments.cpp just after the NOT_WINDOWS disabling of CacheTimeMillis. if (FLAG_IS_DEFAULT(BiasedLockingStartupDelay)) { FLAG_SET_DEFAULT(BiasedLockingStartupDelay, 500); } Alternatively, just change the value of BiasedLockingStartupDelay in globals.hpp to 500. This is the preferred solution if indeed Alacrity shows no startup time degradation on client apps as a result of doing so.