RFR: 8327000: GenShen: Integrate updated Shenandoah implementation of FreeSet into GenShen [v8]

[Kelvin Nilsen]

On Mon, 17 Jun 2024 20:39:33 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Minor refinements to test programs
>>   
>>   TestAllocIntArrays: comments to explain behavior.
>>   TestOldGrowthTriggers: reduce the number of loop iterations so this test
>>   will not time out on less powerful test platforms.
>
> src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp line 138:
> 
>> 136:          if (is_old()) {
>> 137:            heap->old_generation()->decrement_affiliated_region_count();
>> 138:            heap->old_generation()->decrease_capacity(region_size_bytes());
> 
> Should capacity be updated every time affiliated region count changes? If yes, then we could have increase/decrease affiliated region count increase/decrease capacity directly. If no, is this something peculiar to full GC?

This is a good observation and suggestion.  This doesn't seem to be a consistent behavior.  promote_in_place() adjusts affiliated regions without adjusting capacity, but maybe it should.  I'll explore further.

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/440#discussion_r1644632868