8310233: Fix THP detection on Linux

[tstuefe]

Hi all,

This patch is one in a small line of preparatory patches that aim, ultimately, to fix https://bugs.openjdk.org/browse/JDK-8312182 ("THPs cause huge RSS due to thread start timing issue").

This pull request contains a backport of commit [37ca9024](https://github.com/openjdk/jdk/commit/37ca9024ef59d99cae0bd7e25b2e6d3c1e085f97) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Thomas Stuefe on 17 Jul 2023 and was reviewed by Johan Sjölen and David Holmes.

Thanks!

---

Progress

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

Issue

• JDK-8310233: Fix THP detection on Linux (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u.git pull/60/head:pull/60
$ git checkout pull/60

Update a local copy of the PR:
$ git checkout pull/60
$ git pull https://git.openjdk.org/jdk21u.git pull/60/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 60

View PR using the GUI difftool:
$ git pr show -t 60

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u/pull/60.diff

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[bridgekeeper]

👋 Welcome back stuefe! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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

[openjdk]

@tstuefe 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:

8310233: Fix THP detection on Linux

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 no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

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[mlbridge]

Webrevs

• 00: Full (aa8d9cff)

[tstuefe]

got fix approval.

/integrate

[openjdk]

Going to push as commit d6a4e46.
Since your change was applied there have been 21 commits pushed to the master branch:

• 3d38c53: 8311981: Test gc/stringdedup/TestStringDeduplicationAgeThreshold.java#ZGenerational timed out
• 89aea0d: 8314618: RISC-V: -XX:MaxVectorSize does not work as expected
• e1ef69a: Merge
• 8792922: 8314117: RISC-V: Incorrect VMReg encoding in RISCV64Frame.java
• 334b977: 8302017: Allocate BadPaddingException only if it will be thrown
• 16fa055: 8313904: [macos] All signing tests which verifies unsigned app images are failing
• 8a09253: 8314423: Multiple patterns without unnamed variables
• 9d1d5e7: 8313765: Invalid CEN header (invalid zip64 extra data field size)
• 32a1c79: 8309591: Socket.setOption(TCP_QUICKACK) uses wrong level
• 04adfb3: 8314262: GHA: Cut down cross-compilation sysroots deeper
• ... and 11 more: https://git.openjdk.org/jdk21u/compare/956d563e3cb3868c3471a1e6f9758a75743c7963...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tstuefe Pushed as commit d6a4e46.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.