RFR: 8371284: GenShen: Avoid unnecessary card marking [v3]

[Nityanand Rai]

On Mon, 10 Nov 2025 23:33:21 GMT, Nityanand Rai <duke at openjdk.org> wrote:

>> Exclude young-young, old-old and honor UseCondCardMark in dirty card marking.
>
> Nityanand Rai has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Apply suggestions from code review
>   
>   Co-authored-by: Aleksey Shipilëv <shipilev at amazon.de>

We are seeing mixed results, I need to do more validation.

Here are GenShen results over 100+ sample collections

+1.90% philosophers/philosophers_duration p=0.00142 (Wilcoxon)
  Control:      2.620s  (+/-173.82ms)        120
  Test:         2.670s  (+/-205.24ms)        120

+1.68% finagle-chirper/finagle-chirper_duration p=0.00343 (Wilcoxon)
  Control:      2.802s  (+/-130.38ms)        360
  Test:         2.850s  (+/-131.25ms)        360

+1.04% rx-scrabble/rx-scrabble_duration p=0.00000 (Wilcoxon)
  Control:    148.308ms (+/-  0.88ms)        320
  Test:       149.855ms (+/-  0.60ms)        320

-2.48% scrabble/scrabble_duration p=0.00000 (Wilcoxon)
  Control:    169.599ms (+/-  2.90ms)        200
  Test:       165.399ms (+/-  3.40ms)        200

-2.24% scala-kmeans/scala-kmeans_duration p=0.00000 (Wilcoxon)
  Control:    479.973ms (+/-  1.92ms)        200
  Test:       469.219ms (+/-  1.98ms)        200

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PR Comment: https://git.openjdk.org/jdk/pull/28204#issuecomment-3529225545
PR Comment: https://git.openjdk.org/jdk/pull/28204#issuecomment-3549800707