RFR: 8325670: GenShen: Allow old to expand at end of each GC [v2]

[Y. Srinivas Ramakrishna]

On Tue, 20 Feb 2024 16:50:24 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

>> At the end of GC, we set aside collector reserves to satisfy anticipated needs of the next GC.
>> 
>> This PR reverts a change that accidentally prevents old-gen from being enlarged by this action.  The observed failure condition was that mixed evacuations were not able to be performed, because old-gen was not large enough to receive the results of the desired evacuations.
>
> Kelvin Nilsen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Refine calculation of max_old_reserve

LGTM!

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Marked as reviewed by ysr (Committer).

PR Review: https://git.openjdk.org/shenandoah/pull/394#pullrequestreview-1897176282