RFR: 8337511: Implement JEP 404: Generational Shenandoah (Experimental) [v7]

[William Kemper]

On Fri, 15 Nov 2024 17:01:29 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> William Kemper has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 510 commits:
>> 
>>  - Merge branch 'merge-latest' into great-genshen-pr-redux
>>  - Use new CompactHeader forwarding APIs in generational mode
>>  - Merge remote-tracking branch 'jdk/master' into merge-latest
>>  - Merge
>>  - 8343649: Shenandoah: ShenandoahEvacInfo event does not follow JFR guidelines
>>    
>>    Reviewed-by: wkemper
>>  - Merge
>>  - 8343227: GenShen: Fold resource mark into management of preselected regions
>>    
>>    Reviewed-by: kdnilsen
>>  - Merge openjdk/jdk tip into great-genshen-pr-redux
>>  - Merge remote-tracking branch 'jdk/master' into merge-latest
>>  - Merge remote-tracking branch 'jdk/master' into merge-latest
>>  - ... and 500 more: https://git.openjdk.org/jdk/compare/889f9062...5e02b5d8
>
> src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp line 276:
> 
>> 274:     log_info(gc)("GC cancellation took %.3fs", cancel_time);
>> 275:     _cancel_requested_time = 0;
>> 276:   }
> 
> Do we need this? Is this useful?

We could log this at debug? I believe it is useful because this time (currently) is not accounted for in the heuristic's notion of 'cycle time'.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1848979381