RFR: 8317371: GenShen: Needs improved support for humongous allocation [v14]

[Kelvin Nilsen]

On Mon, 23 Oct 2023 17:13:18 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Kelvin Nilsen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 22 commits:
>> 
>>  - Merge remote-tracking branch 'origin/master' into improve-humongous-allocations
>>  - Allow for no old regions in assertion
>>  - One more try at this assertion
>>  - Fix assert to deal with humongous old
>>  - Add a comment
>>  - Fix assertion to deal with humongous accounting
>>  - Restore ShenandoahFullGCThreshold to 3
>>  - In-line two small single-use functions
>>  - Restore _humongous_alloc_failure_gc flag removed in merge conflict
>>  - Merge master
>>  - ... and 12 more: https://git.openjdk.org/shenandoah/compare/e6c788e0...07f7f1f9
>
> src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp line 174:
> 
>> 172: 
>> 173:   {
>> 174:     // TODO: Not sure there is value in logging free-set status right here
> 
> Doesn't early cleanup rebuild the freeset?

I'm not sure.  It does recycle immediate trash.  But it appears to me that the rebuild of freeset following the recycling of trash happens somewhere else.  Of note, the last thing done at the end of each free set rebuild is to log the status, so even if we do rebuild inside entry_cleanup_early(), there would be no need to log the status again right here.

Of course, one reason I left this as a TODO comment instead of just yanking out the code is because it is a bit difficult to understand the control flows, so I thought this could deserve some additional attention at a later time.

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/336#discussion_r1369240000