8322484: 22-b26 Regression in J2dBench-bimg_misc-G1 (and more) on Windows-x64 and macOS-x64

[tschatzl]

Hi all,

please review this improvement to managing region pin counts in g1.

Some applications do millions of Get/ReleasePrimitiveArrayCritical operations per second, in particular some of the j2dbench benchmarks (e.g. vimg_copyarea 10M/s), on some platforms. Every pin/unpin results in an atomic operation that is the cause for these slowdown.

Only Windows seems to be significantly affected.

This suggested change implements a per-region thread local cache storing the current pin/unpin refcount difference, writing it back only when a thread pins/unpin an object in a different region.

For these benchmarks this often reduces the amount of atomic operations to none, or a few handful; the worst improvement I have seen is that effective atomic operations were reduced to 1/10th. Overall all the j2dbench benchmark scores improve.

There is a remaining issue with the vimg_shapes_gradient J2dbench subbenchmark: comparing the original results (before integration of region pinning) with latest jdk23 results, there is a regression of about 5%; this is caused by the backout of a bad compiler change (https://bugs.openjdk.org/browse/JDK-8322985). This will be fixed by its redo CR https://bugs.openjdk.org/browse/JDK-8323116.

Testing: tier1-3, j2dbench, dacapo, specj*, renaissance benchmarks

Thanks,
Thomas

---

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Issue

• JDK-8322484: 22-b26 Regression in J2dBench-bimg_misc-G1 (and more) on Windows-x64 and macOS-x64 (Bug - P2)

Reviewers

• Kim Barrett (@kimbarrett - Reviewer) ⚠️ Review applies to 5f857063
• Albert Mingkun Yang (@albertnetymk - Reviewer) ⚠️ Review applies to 4991abb2

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👋 Welcome back tschatzl! 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.

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Webrevs

• 03: Full - Incremental (5f854e56)
• 02: Full - Incremental (5f857063)
• 01: Full - Incremental (4991abb2)
• 00: Full (7161a0f7)

[tschatzl]

The e1bb807 change passed tier1-7. (The removal of the assert in 4991abb won't invalidate that)

[openjdk]

@tschatzl 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:

8322484: 22-b26 Regression in J2dBench-bimg_misc-G1 (and more) on Windows-x64 and macOS-x64

Reviewed-by: kbarrett, ayang

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At the time when this comment was updated there had been 40 new commits pushed to the master branch:

• af9cd97: 8324800: gcc windows build broken after 8322757
• 8950d68: 8324753: [AIX] adjust os_posix after JDK-8318696
• 65d6bc1: 8324765: C2 SuperWord: remove dead code: SuperWord::insert_extracts
• 525c0cd: 8324752: C2 Superword: remove SuperWordRTDepCheck
• 2e748c9: 8175386: Clarify exception behavior of Types utility methods
• 70f4a4e: 8324786: validate-source fails after JDK-8042981
• ed3272c: 8042981: Strip type annotations in Types' utility methods
• 6d18562: 8324785: ProblemList two tests on linux due to JDK-8315923
• 91d8ea7: 8323835: Updating ASM to 9.6 for JDK 23
• a65a895: 8315923: pretouch_memory by atomic-add-0 fragments huge pages unexpectedly
• ... and 30 more: https://git.openjdk.org/jdk/compare/8c003d83c450a1e706ec5e5ba3d319d84fc4b584...master

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[kimbarrett]

One minor nit in comment. Otherwise looks good.

[tschatzl]

Thanks @albertnetymk @kimbarrett for your reviews
/integrate

[openjdk]

Going to push as commit 0d5f5e1.
Since your change was applied there have been 40 commits pushed to the master branch:

• af9cd97: 8324800: gcc windows build broken after 8322757
• 8950d68: 8324753: [AIX] adjust os_posix after JDK-8318696
• 65d6bc1: 8324765: C2 SuperWord: remove dead code: SuperWord::insert_extracts
• 525c0cd: 8324752: C2 Superword: remove SuperWordRTDepCheck
• 2e748c9: 8175386: Clarify exception behavior of Types utility methods
• 70f4a4e: 8324786: validate-source fails after JDK-8042981
• ed3272c: 8042981: Strip type annotations in Types' utility methods
• 6d18562: 8324785: ProblemList two tests on linux due to JDK-8315923
• 91d8ea7: 8323835: Updating ASM to 9.6 for JDK 23
• a65a895: 8315923: pretouch_memory by atomic-add-0 fragments huge pages unexpectedly
• ... and 30 more: https://git.openjdk.org/jdk/compare/8c003d83c450a1e706ec5e5ba3d319d84fc4b584...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit 0d5f5e1.

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

[tschatzl]

/backport jdk22

[openjdk]

@tschatzl the backport was successfully created on the branch backport-tschatzl-0d5f5e15 in my personal fork of openjdk/jdk22. To create a pull request with this backport targeting openjdk/jdk22:master, just click the following link:

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Hi all,

This pull request contains a backport of commit 0d5f5e15 from the openjdk/jdk repository.

The commit being backported was authored by Thomas Schatzl on 29 Jan 2024 and was reviewed by Kim Barrett and Albert Mingkun Yang.

Thanks!

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[tschatzl]

/backport jdk22u

[openjdk]

@tschatzl the backport was successfully created on the branch backport-tschatzl-0d5f5e15 in my personal fork of openjdk/jdk22u. To create a pull request with this backport targeting openjdk/jdk22u:master, just click the following link:

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Hi all,

This pull request contains a backport of commit 0d5f5e15 from the openjdk/jdk repository.

The commit being backported was authored by Thomas Schatzl on 29 Jan 2024 and was reviewed by Kim Barrett and Albert Mingkun Yang.

Thanks!

If you need to update the source branch of the pull then run the following commands in a local clone of your personal fork of openjdk/jdk22u:

$ git fetch https://github.com/openjdk-bots/jdk22u.git backport-tschatzl-0d5f5e15:backport-tschatzl-0d5f5e15
$ git checkout backport-tschatzl-0d5f5e15
# make changes
$ git add paths/to/changed/files
$ git commit --message 'Describe additional changes made'
$ git push https://github.com/openjdk-bots/jdk22u.git backport-tschatzl-0d5f5e15

⚠️ @tschatzl You are not yet a collaborator in my fork openjdk-bots/jdk22u. An invite will be sent out and you need to accept it before you can proceed.