RFR: 8373225: GenShen: More adaptive old-generation growth heuristics [v5]

[Kelvin Nilsen]

On Wed, 10 Dec 2025 22:49:18 GMT, Y. Srinivas Ramakrishna <ysr at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove FRACTIONAL_DENOMINATOR constat
>
> src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp line 96:
> 
>> 94:           100, EXPERIMENTAL,                                                \
>> 95:           "(Generational mode only) Even if the usage of old generation "   \
>> 96:           "is below ShenandoahIgnoreOldGrowthBelowPercentage, "             \
> 
> The reference to `ShenandoahIgnoreOldGrowthBelowPercentage` (SIOGBP) seems to me to be spurious and confusing. I think this might be a simpler phrasing, without any reference to SIOGBP:
> 
> 
> \\ Trigger an Old collection if Old generation usage has grown,
> \\ and this many Young collections have happened,
> \\ since the last Old collection.

I'll reorder this paragraph to emphasize the triggering.  I don't want to totally remove the mention of ShenandoahIngoreOldGrowthBelowPercentage because the descriptions of these two parameters might otherwise appear to contradict each other.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28561#discussion_r2611282109