8360783: CTW: Skip deoptimization between tiers

[shipilev]

When profiling CTW runs, I noticed we spend a lot of time dealing with deoptimization. We do this excessively, deoptimizing before compilation on every tier. This is excessive: Hotspot honors compilation requests on subsequent levels without the need for explicit deoptimization. Not doing deopt between tiers greatly improves CTW performance.

A taste of improvements, about 15% less CPU spent:

$ time make test TEST=applications/ctw/modules

# Current
real	5m1.616s
user	79m41.398s
sys	14m39.607s

# Patched
real	3m55.411s
user	69m19.227s
sys	5m24.323s

The compilation still works as expected, progressing through tiers 1..4:

$ JAVA_OPTIONS="-XX:+PrintCompilation -XX:CICompilerCount=2" ./ctw.sh modules:jdk.compiler | tee out
...
$ grep sun.tools.serialver.resources.serialver_de::getContents out
101783 55033    b  1       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)
101785 55036    b  2       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)
101786 55033       1       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)   made not entrant: not used
101786 55038    b  3       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)
101787 55036       2       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)   made not entrant: not used
101792 55040    b  4       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)
101797 55038       3       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)   made not entrant: not used
101798 55040       4       sun.tools.serialver.resources.serialver_de::getContents (108 bytes)   made not entrant: marked for deoptimization

---

Progress

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Issue

• JDK-8360783: CTW: Skip deoptimization between tiers (Enhancement - P4)

Reviewers

• Tobias Hartmann (@TobiHartmann - Reviewer)
• Manuel Hässig (@mhaessig - Committer)
• Damon Fenacci (@dafedafe - Committer)

Reviewing

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[openjdk]

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

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

8360783: CTW: Skip deoptimization between tiers

Reviewed-by: thartmann, mhaessig, dfenacci

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At the time when this comment was updated there had been 50 new commits pushed to the master branch:

• b32ccf2: 8361092: Remove trailing spaces in x86 ad files
• 0572b6e: 8360887: (fs) Files.getFileAttributeView returns unusable FileAttributeView if UserDefinedFileAttributeView unavailable (aix)
• d1052c7: 8355478: DoubleActionESC.java fails intermittently
• ... and 47 more: https://git.openjdk.org/jdk/compare/1fa090524a7c3bb5f2c92fb0f7217b9277ade9d9...master

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[mlbridge]

Webrevs

• 01: Full - Incremental (34913a48)
• 00: Full (7dce90f7)

[TobiHartmann]

Looks good to me.

[mhaessig]

Those are quite some time savings! Thank you for fixing this.

Looks good to me.

[shipilev]

Thanks, I think I need a quick re-review after the amendment.

[dafedafe]

Thanks @shipilev! I really welcome any change that makes CTW a bit faster 🙂 Looks good to me.

[shipilev]

Thanks! Here goes.

/integrate

[openjdk]

@shipilev This pull request has not yet been marked as ready for integration.

[shipilev]

Aw. Thanks! Here goes again.

/integrate

[openjdk]

Going to push as commit cd6caed.
Since your change was applied there have been 50 commits pushed to the master branch:

• b32ccf2: 8361092: Remove trailing spaces in x86 ad files
• 0572b6e: 8360887: (fs) Files.getFileAttributeView returns unusable FileAttributeView if UserDefinedFileAttributeView unavailable (aix)
• d1052c7: 8355478: DoubleActionESC.java fails intermittently
• ... and 47 more: https://git.openjdk.org/jdk/compare/1fa090524a7c3bb5f2c92fb0f7217b9277ade9d9...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit cd6caed.

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