RFR: 8338929: Make Metaspace::deallocate space-aware [v2]

[Thomas Stuefe]

On Mon, 26 Aug 2024 14:53:24 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
>> 
>>  - improve comments
>>  - Merge branch 'master' into make-deallocate-space-aware
>>  - copyrights
>>  - fast is-in-class-space check
>
> Nit comment change and question for my own clarification, but this looks fine.

Hi @coleenp 

> This comment should then be "or the CDS archive", since the function is contains() and includes the non-class metaspace. That is, is_in_shared_metaspace() includes all of the CDS archive. I don't think the CompressedKlassPointers:::range limit is in the middle of the CDS archive memory area, unless CDS was changed without me noticing to separate class and non-class metadata (I hope not).

(GitHub, why can I not reply to comments inline? )

CDS also has heap parts, which are not in the Klass decoding range. That is why I named it the "Klass portion". I could also name it the "Metaspace" portion, but that is confusing, since its not in metaspace. "Metadata portion" maybe? 

> So this does _not_ include the Klasses in the CDS archive, it really is only useful for deallocation. I don't need this to be a comment update, just making sure I follow.

Yes, that is correct.

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PR Comment: https://git.openjdk.org/jdk/pull/20701#issuecomment-2312782760