RFR (S): 8078669: G1 applies SurvivorAlignmentInBytes to both survivor and old gen

Filipp Zhinkin filipp.zhinkin at gmail.com
Wed May 13 18:57:00 UTC 2015

Hi Thomas,

On Wed, May 13, 2015 at 5:33 PM, Thomas Schatzl
<thomas.schatzl at oracle.com> wrote:
> Hi all,
>   can I have reviews for the following small fix: since JDK-8060025
> survivor alignment has been applied to both survivor and old gen regions
> (if enabled of course).
> This has gone unnoticed, because the tests somehow detected that in this
> situation everyhing is fine due to "someone else that allocated
> objects".

Without such check tests may fail when executed with JFR or some agent.
If it's an issue, then I guess it will be better to improve it instead
of eliminating at all.


> The change fixes the problem (in g1Allocator.hpp), and removes this
> strange bailout in the tests, at the same time disabling PLAB resizing
> which causes too much wasted space (extra allocation) that otherwise
> causes the test to fail.
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8078669
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8078669/webrev/
> Testing:
> no performance changes in object copy times, several JPRT runs in the
> process, making sure there are no failures.
> Thanks,
>   Thomas

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