RFR: JDK-8262068: Improve G1 Full GC by skipping compaction for regions with high survival ratio [v8]

[Hamlin Li]

On Thu, 11 Mar 2021 15:19:36 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix bot crash.
>
> src/hotspot/share/gc/g1/g1FullGCMarker.hpp line 104:
> 
>> 102: 
>> 103:   void flush_mark_region_cache() {
>> 104:     if (MarkSweepDeadRatio > 0) {
> 
> Drop this check to make the code more straightforward. Other code like in PR #2579 might find this information useful too. Maybe this could even be factored out in a separate CR.

Hi Thomas,
Do you mean to collect liveness info in mark phase when G1 full gc, even if MarkSweepDeadRatio is == 0 (which means do not skip any regions when compaction)? If this is the request, I can file a new bug for this liveness collection in G1 full gc.
For the jfr PR #2579 , I think it's can be addressed in a separate bug which depends on the one for liveness collection.
I will file/work these 2 new bugs (liveness collection when g1 full gc, jfr liveness event after full gc) if this is what you suggested.

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PR: https://git.openjdk.java.net/jdk/pull/2760