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

Jon Masamitsu jon.masamitsu at oracle.com
Wed May 13 21:15:40 UTC 2015

On 5/13/2015 7:33 AM, Thomas Schatzl 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".
> The change fixes the problem (in g1Allocator.hpp), and removes this

The CR suggests that this change in g1Allocator.hpp is a workaround while
waiting for a better fix.  Still true?

The change looks correct as a fix for the specific problem.

I'll let you discuss the tests with Dmitry.


> 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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