RFR (S/M): 8178105: Switch mark bitmaps during Remark

Thomas Schatzl thomas.schatzl at oracle.com
Fri Apr 6 17:59:23 UTC 2018


Hi,

  ping for a second reviewer....

Thomas

On Thu, 2018-03-29 at 16:35 +0200, Thomas Schatzl wrote:
> Hi all,
> 
>   can I have reviews for this small change that makes G1 switch the
> mark bitmaps already during the Remark pause as opposed waiting until
> Cleanup?
> 
> This is the last step before G1 can reclaim regions at Remark, which
> means that empty regions can be cleaned up more more quickly than
> before (JDK-8154528, coming soon :)).
> 
> The main changes apart from actually switching the bitmaps consist of
> updating the liveness information, i.e. how many bytes are live in a
> region, now already available at Remark since JDK-8197850, also at
> the
> same time.
> 
> Previously G1 used the Rebuild Remsets phase to calculate that at the
> same time.
> 
> I could not find significant differences in timing.
> 
> This change depends on the recent g1ConcurrentMark refactorings,
> particularly JDK-8200234.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8178105
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8178105/
> Testing:
> hs-tier 1-5
> 
> Thanks,
>   Thomas
> 



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