8295476: Split G1 cost per byte predictor on gc phase

[tschatzl]

Hi,

please review this change to the cost-per-byte predictor to be split on gc phase (young-only/mixed) instead of during marking/outside of marking.

The reason is that the distinction between young-only/mixed of these values is higher than marking/outside of marking, although the latter degrades somewhat to the former in case of continuous concurrent marking where both are almost equivalent anyway. I believe that has been the original reason to do the marking/not-marking distinction.

I also removed the implied 10% extra cost for copies during marking (i.e. during the young-only phase). I could not find any particular reason why copying would be more expensive then with the current code base.

The distinction in general makes sense as the data copied during young-only and mixed is different (only short-lived data vs. short+long-lived data).

Testing: gha, examining predictions with some benchmarks

Thanks,
Thomas

---

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Issue

• JDK-8295476: Split G1 cost per byte predictor on gc phase

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)
• Ivan Walulya (@walulyai - Reviewer)
• Kim Barrett (@kimbarrett - Reviewer)

Reviewing

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• 00: Full (9a8d3e3f)

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

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8295476: Split G1 cost per byte predictor on gc phase

Reviewed-by: ayang, iwalulya, kbarrett

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At the time when this comment was updated there had been 59 new commits pushed to the master branch:

• 50d91a3: 8057113: (fs) Path should have a method to obtain the filename extension
• d17bf51: 8295914: Add a header to generated HTML files in specs
• 9911405: 8282958: Rendering issues of borders, TextFields on Windows High-DPI systems
• 2fb64a4: 8296162: [aarch64] Remove unused Address::_is_lval
• 15b8b45: 8296161: [aarch64] Remove unused "pcrel" addressing mode tag
• f829b5a: 8280378: [IR Framework] Support IR matching for different compile phases
• da0ae51: 8296167: test/langtools/tools/jdeps/jdkinternals/ShowReplacement.java failing after JDK-8296072
• 0d0bd7b: 8296072: CertAttrSet::encode and DerEncoder::derEncode should write into DerOutputStream
• 37107fc: 8296007: crash in runtime/DefineClass/NullClassBytesTest.java
• 4999f2c: 8156593: DataOutput.write(byte[],int,int) and its implementations do not specify index out bounds
• ... and 49 more: https://git.openjdk.org/jdk/compare/d393e051e660d05b645a2d148c6cdfc21b1d347e...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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[walulyai]

Lgtm!

[kimbarrett]

Looks good.

[tschatzl]

Thanks @albertnetymk @walulyai @kimbarrett for your reviews
/integrate

[openjdk]

Going to push as commit 8de3eda.
Since your change was applied there have been 60 commits pushed to the master branch:

• 2634eff: 8295646: Ignore zero pairs in address descriptors read by dwarf parser
• 50d91a3: 8057113: (fs) Path should have a method to obtain the filename extension
• d17bf51: 8295914: Add a header to generated HTML files in specs
• 9911405: 8282958: Rendering issues of borders, TextFields on Windows High-DPI systems
• 2fb64a4: 8296162: [aarch64] Remove unused Address::_is_lval
• 15b8b45: 8296161: [aarch64] Remove unused "pcrel" addressing mode tag
• f829b5a: 8280378: [IR Framework] Support IR matching for different compile phases
• da0ae51: 8296167: test/langtools/tools/jdeps/jdkinternals/ShowReplacement.java failing after JDK-8296072
• 0d0bd7b: 8296072: CertAttrSet::encode and DerEncoder::derEncode should write into DerOutputStream
• 37107fc: 8296007: crash in runtime/DefineClass/NullClassBytesTest.java
• ... and 50 more: https://git.openjdk.org/jdk/compare/d393e051e660d05b645a2d148c6cdfc21b1d347e...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit 8de3eda.

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