RFR: 8327097: GenShen: Align PLAB sizes down rather than up [v3]

[Kelvin Nilsen]

On Mon, 18 Mar 2024 17:55:15 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Disable TestHumongousThreshold test on generic-all for now
>>    
>>    This has experienced timeout failures on multiple platforms.
>>  - Cleanup code in response to reviewer feedback
>
> test/hotspot/jtreg/ProblemList.txt line 94:
> 
>> 92: gc/TestAllocHumongousFragment.java#static 8298781 generic-all
>> 93: gc/stress/gclocker/TestExcessGCLockerCollections.java 8229120 generic-all
>> 94: gc/shenandoah/TestHumongousThreshold.java#default 8327000 macosx-aarch64
> 
> Disable this on generic-all until 8327000 resolved.

Done

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/401#discussion_r1530397373