RFR: 8336086: G1: Use one G1CardSet instance for all young regions [v2]

[Albert Mingkun Yang]

On Mon, 5 Aug 2024 14:42:45 GMT, Ivan Walulya <iwalulya at openjdk.org> wrote:

>> Hi all,
>> 
>> Please review this change to assign a single G1CardSet to all young regions. As young regions are collected at the same, and we do not have young-to-young remembered sets, we can maintain a single G1CardSet for all young regions.
>> 
>> This reduces the memory overhead of the G1CardSets and the time taken to merge per region G1CardSets during GC pause.
>> 
>> Testing: Tier 1-5
>
> Ivan Walulya has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:
> 
>  - Albert Review
>  - Merge remote-tracking branch 'upstream/master' into YoungOnlyCardSet
>  - Merge remote-tracking branch 'upstream/master' into YoungOnlyCardSet
>  - cleanup
>  - merge
>  - Merge remote-tracking branch 'upstream/master' into YoungOnlyCardSet
>  - init

Marked as reviewed by ayang (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/20134#pullrequestreview-2227206638