RFR(s): 8145312: CMS: There is insufficient memory with CMSSamplingGrain=1

Dmitry Dmitriev dmitry.dmitriev at oracle.com
Tue Mar 8 20:26:06 UTC 2016


Hi Sangheon,

Please, don't exclude testing of max range for CMSSamplingGrain flag, 
because in this case additional big values will be excluded too. Max 
value for CMSSamplingGrain will violates constraint, but it's ok for 
testing.

Thank you,
Dmitry

On 08.03.2016 11:00, sangheon wrote:
> Hi all,
>
> Could I have some reviews for CMSSamplingGrain flag?
>
> The flag is used to calculate points at which the young gen should be 
> partitioned for doing parallel work, so it only makes sense to 
> partition at a granularity equal to or larger than the object size.
>
> I am proposing to change the minimum value of CMSSamplingGrain from 
> '1' to 'ObjectAlignmentInBytes'.  (ObjectAlignmentInBytes has a range 
> of [8, 256]).
>
> In addition, I added a constraint function to avoid an arithmetic 
> overflow by its maximum value.
>
> CR: https://bugs.openjdk.java.net/browse/JDK-8145312
> Webrev: http://cr.openjdk.java.net/~sangheki/8145312/webrev.00/
> Testing: JPRT, RBT for all platforms including embedded
>
> Thanks,
> Sangheon



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