RFR (S): 8059758: Startup benchmark performance and footprint regressions with JDK-8038423
jesper.wilhelmsson at oracle.com
Mon Oct 6 12:23:27 UTC 2014
Maybe add a comment about why the newly added argument is not used in
Thomas Schatzl skrev 6/10/14 13:48:
> Hi all,
> can I have reviews for the following change that allows lazy
> initialization of G1 auxiliary data structures again to remove a
> footprint and performance regression for startup benchmarks with G1?
> The problem is that with recent changes that allowed G1 to decommit
> regions within the heap freely, the VM always initialized associated
> auxiliary data structures (BOT, card table, mark bitmaps).
> This works somewhat against OSes lazy initialization of committed pages
> where they are actually only backed by physical memory on the first
> These startup benchmarks never actually use this memory because they are
> so simple, so this causes performance and footprint regression with the
> mentioned change.
> This fix fixes these regressions by passing around information to the
> various notifications whether the recently committed memory can be
> considered already zero or not, and skips the data structure
> initialization if possible (i.e. if the reset values equal the default
> initialization values of newly committed pages).
> jprt, startup benchmarks
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the hotspot-gc-dev