[jdk21u-dev] RFR: 8315923: pretouch_memory by atomic-add-0 fragments huge pages unexpectedly

[Aleksey Shipilev]

On Fri, 5 Jul 2024 08:55:58 GMT, Liming Liu <lliu at openjdk.org> wrote:

> This pull request ports JDK-8315923 back to JDK-21, as JDK-21 still uses atomic-add-0 to pretouch memory and results fragmented huge pages. This backport has the following differences from its original version:
> 
> - TestTransparentHugePageUsage.java gets deleted as it was deleted in JDK-8324776;
> - nullptr is adopted in pretouch_thp_and_use_concurrent, as it is a part of  JDK-8327171;
> - JDK-8324781 is included, as JDK-8324781 only makes changes to testcases.

I have questions:

1. If [JDK-8324781](https://bugs.openjdk.org/browse/JDK-8324781) is included, you need to say `/issue add JDK-8324781`, and later request approval for it as well.
2. Looking at issue links, what about [JDK-8325218](https://bugs.openjdk.org/browse/JDK-8325218)?

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Changes requested by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk21u-dev/pull/825#pullrequestreview-2162985260