RFR: 8316608: Enable parallelism in vmTestbase/gc/vector tests

[Aleksey Shipilev]

On Tue, 3 Oct 2023 14:02:09 GMT, Soumadipta Roy <duke at openjdk.org> wrote:

> The commit includes changes to unblock parallelism for more `hotspot:tier4` tests. in `vmTestbase/gc/vector` tests.
> 
> Below are the before and after run comparisons:
> 
> # Fastdebug
> before: 3480.71s user 83.97s system 830% cpu 7:09.41 total
> after: 2214.52s user 63.19s system 2374% cpu 1:35.94 total
> 
> # Release
> before: 1369.61s user 147.03s system 371% cpu 6:48.63 total
> after: 1130.28s user 110.97s system 2478% cpu 50.089 total

I think this is good, but @tschatzl and @lmesnik need to be looped in for visibility.

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16028#pullrequestreview-1656903673