RFR: 8365922: Parallel: Group uses of GCTimeRatio to a single location [v2]

[Thomas Schatzl]

On Wed, 27 Aug 2025 09:56:01 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Unify all accesses of `GCTimeRatio` to a single place so that Parallel gets a coherence view of its value within the pause, if the global variable's value is ever changed.
>> 
>> Test: tier1-3
>
> Albert Mingkun Yang 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 three additional commits since the last revision:
> 
>  - review
>  - Merge branch 'master' into pgc-gc-time-ratio-prepare-management
>  - pgc-gc-time-ratio-prepare-management

Marked as reviewed by tschatzl (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/26881#pullrequestreview-3173331324