RFR: 8254167 G1: Record regions where evacuation failed to provide targeted iteration

[Hamlin Li]

On Fri, 27 Aug 2021 04:09:52 GMT, Hamlin Li <mli at openjdk.org> wrote:

> This is a try to optimize evcuation failure for regions.
> I record evacuation failed regions, and iterate these regions directly rather than iterate the whole cset.
> The implementation reuses and refactors some of the existing data in g1CollectedHeap (_regions_failed_evacuation, _num_regions_failed_evacuation), and records these regions in an array, and iterate this array later in post evacuation phase.
> 
> I have 2 implementations:
> 
> - 1) CHT
> - 2) bitmap (reuse _regions_failed_evacuation in g1CollectedHeap)
> 
> This implementation does not consider work distribution as mentioned in JDK-8254167 yet. But seems it already get better&stable performance gain than origin. We could improve it further later if work distribution is necessary.
> 
> I will attach the perf data in JBS.

I will push the bitmap version later

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PR: https://git.openjdk.java.net/jdk/pull/5272