8268127: Shenandoah: Heap size may be too small for region to align to large page size

[zhengyu123]

I would like to backport this Shenandoah specific patch to 16u, which allows to fallback to regular pages for regions, if heap size is too small to allow regions to use large pages.

The original patch does not apply cleanly, resolved then manually.

Test:
Manually test to ensure large pages are used. Failed w/o the patch and passed with it.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8268127: Shenandoah: Heap size may be too small for region to align to large page size

Reviewers

• Roman Kennke (@rkennke - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk16u pull/128/head:pull/128
$ git checkout pull/128

Update a local copy of the PR:
$ git checkout pull/128
$ git pull https://git.openjdk.java.net/jdk16u pull/128/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 128

View PR using the GUI difftool:
$ git pr show -t 128

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jdk16u/pull/128.diff

[bridgekeeper]

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[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 00: Full (93b204ad)

[openjdk]

@zhengyu123 This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8268127: Shenandoah: Heap size may be too small for region to align to large page size

Reviewed-by: rkennke

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 42 new commits pushed to the master branch:

• 7dcedb6: Merge
• 3b56f0b: Merge
• b3b4dc3: 8268173: Wrong GA date in JDK 11.0.12 and 16.0.2 versions
• b609c51: Merge
• 6fc68c2: Merge
• 9a4b6db: Merge
• c44d517: Merge branch 'jdk16.0.2' into 'jdk16.0.2'
• 0a52d01: 8266205: Update milestone to fcs for jdk16.0.2+4
• ee4633d: Merge
• 6d8f828: Merge
• ... and 32 more: https://git.openjdk.java.net/jdk16u/compare/d2d95335667758c5be7a7f3d8150f8556b869dac...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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