JDK-7037276 : Unnecessary double traversal of dirty card windows
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs21
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2011-04-17
  • Updated: 2013-06-22
  • Resolved: 2011-05-10
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JDK 6 JDK 7 Other
6u60Fixed 7Fixed hs21Fixed
Related Reports
Relates :  
JDK-6883834 - ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests
Relates :  
JDK-7036837 - cardtable interface and class hierarchy simplification
Description
non_clean_card_iterate() collects contiguous ranges of dirty cards
which are then processed by ClearNoncleanCardWrapper in a second traversal.
There is really no need for two traversals, rather non_clean_card_iterate()
need not be used and all of the work can instead accomplished in a single
traversal of the cards in the range being scanned by CleanNoncleanCardWrapper.
This might even improve performance by a bit (but more importantly it would
reduce the complexity and interdependencies within the card table hierarchy).
Comments
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-rt/hotspot/rev/c48ad6ab8bdf
05-05-2011
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/c48ad6ab8bdf
21-04-2011
EVALUATION Yes.
17-04-2011