8265239: Shenandoah: Shenandoah heap region count could be off by 1

[zhengyu123]

henandoah uses MaxHeapSize to calculate region size, then aligns up heap size to region size alignment, but when it calculates region count, it does not take alignment into account, that may result 1 region short than actual count.

MaxHeapSize eventually aligns to HeapAlignment (which is region size in Shenandoah case) in GCArguments::initialize_heap_flags_and_sizes(), but it is too late.

Test:

• hotspot_gc_shenandoah

---

Progress

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Issue

• JDK-8265239: Shenandoah: Shenandoah heap region count could be off by 1

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/3504/head:pull/3504
$ git checkout pull/3504

Update a local copy of the PR:
$ git checkout pull/3504
$ git pull https://git.openjdk.java.net/jdk pull/3504/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 3504

View PR using the GUI difftool:
$ git pr show -t 3504

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/3504.diff

[bridgekeeper]

👋 Welcome back zgu! 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]

@zhengyu123 The following labels will be automatically applied to this pull request:

• hotspot-gc
• shenandoah

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[mlbridge]

Webrevs

• 00: Full (81decec2)

[shipilev]

Looks fine.

[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:

8265239: Shenandoah: Shenandoah heap region count could be off by 1

Reviewed-by: shade

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 37 new commits pushed to the master branch:

• fc89fe6: 8265119: G1: update_remset_before_rebuild mixes liveness in words with liveness in bytes
• 50f3da8: 8264480: Unreachable code in nmethod.cpp inside #ifdef DEBUG
• e0151a6: 8264104: Eliminate unnecessary vector mask conversion during VectorUnbox for floating point VectorMask
• 64e2130: 8262108: SimpleDateFormat formatting broken for sq_MK Locale
• 3423f3e: 8265180: JvmtiCompiledMethodLoadEvent should include the stub section of nmethods
• f6e54f2: 8258794: Support for CLDR version 39
• e89fd15: 8261301: StringWriter.flush() is NOOP but documentation does not indicate it
• 0b1b5c8: 8264373: javac hangs when annotation is declared with sealed public modifier
• c7da64a: 8265302: ProblemList runtime/logging/RedefineClasses.java on linux-x64 -Xcomp
• 838c11f: 8265293: ProblemList java/foreign/TestDowncall.java on macosx-aarch64
• ... and 27 more: https://git.openjdk.java.net/jdk/compare/57f86a071e927929c70ba3314cafacda26d6a1a6...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[zhengyu123]

/integrate

[openjdk]

@zhengyu123 Since your change was applied there have been 42 commits pushed to the master branch:

• 17b6592: 8265335: Epsilon: Minor typo in EpsilonElasticTLABDecay description
• 10ec38f: 8262462: IGV: cannot remove specific groups imported via network
• 7137328: 8264958: C2 compilation fails with assert "n is later than its clone"
• 1d66a15: 8265330: G1: Fix comment in G1FullGCPrepareTask::G1CalculatePointersClosure
• b4ba74e: 8264987: G1: Fill BOTs for Survivor-turned-to-Old regions in full gc
• fc89fe6: 8265119: G1: update_remset_before_rebuild mixes liveness in words with liveness in bytes
• 50f3da8: 8264480: Unreachable code in nmethod.cpp inside #ifdef DEBUG
• e0151a6: 8264104: Eliminate unnecessary vector mask conversion during VectorUnbox for floating point VectorMask
• 64e2130: 8262108: SimpleDateFormat formatting broken for sq_MK Locale
• 3423f3e: 8265180: JvmtiCompiledMethodLoadEvent should include the stub section of nmethods
• ... and 32 more: https://git.openjdk.java.net/jdk/compare/57f86a071e927929c70ba3314cafacda26d6a1a6...master

Your commit was automatically rebased without conflicts.

Pushed as commit ff5bb8c.

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