RFR: JDK-8079556: BACKOUT - Determining the desired PLAB size adjusts to the the number of threads at the wrong place

Jesper Wilhelmsson jesper.wilhelmsson at oracle.com
Thu May 7 10:06:27 UTC 2015


Thanks Bengt!
/Jesper

Bengt Rutisson skrev den 7/5/15 11:18:
>
> On 2015-05-07 10:34, Jesper Wilhelmsson wrote:
>> Hi,
>>
>> Please review this backout of JDK-8073204 - Determining the desired PLAB size
>> adjusts to the the number of threads at the wrong place
>>
>> After the change the size returned by PLABStats::desired_plab_sz() can get
>> below the minimum PLAB size due to truncating integer division in that
>> function, and actually missing alignment. This results in several places
>> getting the wrong results because of this broken invariant.
>>
>> The fix will take more than a day and this change is now blocking a push of
>> hs-gc to main.
>>
>> Thomas prepared this backout, I have reviewed it (looks good), so we need
>> another Reviewer to push it.
>>
>> Backout bug: https://bugs.openjdk.java.net/browse/JDK-8079556
>> Webrev: http://cr.openjdk.java.net/~jwilhelm/8073204/webrev_backout.00/
>> Original change: http://hg.openjdk.java.net/jdk9/hs-gc/hotspot/rev/d57d15fb074b
>>
>> The backout applies cleanly to latest hs-gc.
>
> Looks good.
>
> Bengt
>
>>
>> Thanks,
>> /Jesper
>


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