RFR: 8329223: Parallel: Parallel GC resizes heap even has -Xms = -Xmx

[Bernd]

On Thu, 28 Mar 2024 19:21:01 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> Parallel GC resizes old gen even when setting -Xms == -Xmx. 
> 
> During GC argument setup, it always set `MinOldSize = GenAlignment` and does not make any adjustment when `-Xms == -Xmx`, while does the adjustment for young gen [here](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/gc/shared/genArguments.cpp#L250)

src/hotspot/share/gc/parallel/psOldGen.cpp line 297:

> 295: 
> 296:   new_size = align_up(new_size, alignment);
> 297:   new_size = clamp(new_size, min_gen_size(), max_gen_size());

Is that a merge conflict and are min/max_gen_size() alligned?

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PR Review Comment: https://git.openjdk.org/jdk/pull/18539#discussion_r1543847135