JDK-6928065 : G1: use existing command line parameters to set the young generation size
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs17
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2010-02-19
  • Updated: 2013-09-18
  • Resolved: 2011-03-08
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6u21Fixed 7Fixed hs17Fixed
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This is part of the G1 command line parameter changes enumerated in 6928059.

Currently, G1 will auto-tune the young generation size if the G1YoungGenSize parameter is not set. If G1YoungGenSize is set, G1 will use that as the young gen size.

To be consistent with the other GCs, G1 should observe UseAdaptiveSizePolicy to decide whether to auto-tune the young generation size. NewSize / MaxNewSize (and also -Xmn) should dictate the initial max size.

PUBLIC COMMENTS Due to time pressure to get the fix in, I'm making the scope of this CR a bit narrower. We'll still enable/disable the ergonomic youn gen sizing with +/-UseAdaptiveSizePolicy, set the young gen size with NewSize or NewRatio, and pick up the same default young gen size as the other GCs, if ergonomics are turned off. However, if ergonomics are turned on we'll ignore NewSize / MaxNewSize and the ergonomic code can resize the young generation as it wishes (i.e., G1 will operate as it operated before, only the parameter names change). Obeying NewSize / MaxNewSize when ergonomics are enabled will be done as a separate CR (6929868).

EVALUATION ChangeSet=http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/a1c410de27e4,ChangeRequest=6928065

EVALUATION See Comments.