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

[Liming Liu]

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.

This pull request has now been integrated.

Changeset: cb40bc22
Author:    Liming Liu <lliu at openjdk.org>
Committer: Aleksey Shipilev <shade at openjdk.org>
URL:       https://git.openjdk.org/jdk21u-dev/commit/cb40bc225c4c4c8c9d95bdd2e60cef94c56117cf
Stats:     120 lines in 11 files changed: 98 ins; 8 del; 14 mod

8315923: pretouch_memory by atomic-add-0 fragments huge pages unexpectedly
8324781: runtime/Thread/TestAlwaysPreTouchStacks.java failed with Expected a higher ratio between stack committed and reserved
8325218: gc/parallel/TestAlwaysPreTouchBehavior.java fails

Reviewed-by: shade
Backport-of: a65a89522d2f24b1767e1c74f6689a22ea32ca6a

-------------

PR: https://git.openjdk.org/jdk21u-dev/pull/825