RFR: 8376839: GenShen: Improve performance of evacuations into the old generation [v4]

[Kelvin Nilsen]

On Thu, 5 Feb 2026 17:31:58 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Avoid update call when there is no work to be done
>
> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp line 1558:
> 
>> 1556:       // coalesce-and-fill processing.
>> 1557:       r->end_preemptible_coalesce_and_fill();
>> 1558:       _heap->old_generation()->clear_cards_for(r);
> 
> Clearing the card table and object starts when allocating new old regions likely contributed to slower evacuations in old generation. Cards are now cleared when old regions are recycled. We must also do this when a full GC switches the affiliation of regions from young to old.

Thanks for commenting on this detail.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29511#discussion_r2785369427