JDK-6818524 : G1: use ergonomic resizing of PLABs
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs15
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2009-03-17
  • Updated: 2013-09-18
  • Resolved: 2012-08-27
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7u40Fixed 8Fixed hs24Fixed
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Right now, G1 uses fixed size PLABs for allocation during GC (set by the imaginatively-named parameter -XX:ParallelGCG1AllocBufferSize). It'd be nice to do what CMS does and use dynamic ergonomic resizing of the PLABs.

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-gc/hotspot/rev/aaf61e68b255

PUBLIC COMMENTS This might have dependency on 6722568, as if PLABs are very large and appear as a single allocation to the BOT might impose a non-trivial scanning overhead which might cancel out any benefits we'll get out of using large PLABs in the first place.

EVALUATION Performance anomalies being currently investigated.