8301869: Regression ~14% in J2dBench-bimg_misc-* in 21-b5 only on linux-aarch64

[jayathirthrao]

Under https://bugs.openjdk.org/browse/JDK-8264846 we moved to -O3 level of gcc optimizations from -O1 level for libawt build. This improved our J2DBench performance numbers in some options considerably.

Recent changes done under https://bugs.openjdk.org/browse/JDK-8299337 causes difference in generated code by gcc and this is resulting in performance regression for bimg_misc-* J2DBench options in our performance servers. Under https://bugs.openjdk.org/browse/JDK-8299337 we have just removed unused variables and it is a cleanup task.

We can force gcc to generate position independent code by using -fpic option.Also i have removed -fgcse-after-reload option for gcc, because this is by default covered under -O3 level of optimization introduced under https://bugs.openjdk.org/browse/JDK-8264846.

With this change bimg_misc-* J2DBench option performance regression is resolved and there are no regression in other options of J2DBench or SwingMark and it is verified in our performance servers.

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Issue

• JDK-8301869: Regression ~14% in J2dBench-bimg_misc-* in 21-b5 only on linux-aarch64

Reviewers

• Erik Joelsson (@erikj79 - Reviewer) ⚠️ Review applies to e8d25674

Contributors

• Sergey Bylokhov <serb@openjdk.org>

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[jayathirthrao]

/contributor add serb

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@jayathirthrao
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[mlbridge]

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• 02: Full - Incremental (135883db)
• 01: Full - Incremental (e8d25674)
• 00: Full (0c39e4c3)

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8301869: Regression ~14% in J2dBench-bimg_misc-* in 21-b5 only on linux-aarch64

Co-authored-by: Sergey Bylokhov <serb@openjdk.org>
Reviewed-by: erikj

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At the time when this comment was updated there had been 483 new commits pushed to the master branch:

• b062b1b: 8304743: Compile_lock and SystemDictionary updates
• df819cf: 8304945: StringBuilder and StringBuffer should implement Appendable explicitly
• 312bbe7: 8305485: Problemlist runtime/Thread/TestAlwaysPreTouchStacks.java
• 50e31e0: 8305442: (bf) Direct and view implementations of CharBuffer.toString(int, int) do not need to catch SIOBE
• 85e3974: 8304014: Convert test/jdk/java/util/zip/ZipFile/CorruptedZipFiles.java to junit
• 40aea04: 8278268: (ch) InputStream returned by Channels.newInputStream should have fast path for FileChannel targets
• 9b9b5a7: 8302323: Add repeat methods to StringBuilder/StringBuffer
• dd7ca75: 8305478: [REDO] disable gtest/NMTGtests.java sub-tests failing due to JDK-8305414
• f9827ad: 8288109: HttpExchangeImpl.setAttribute does not allow null value after JDK-8266897
• 6010de0: 8305417: disable gtest/NMTGtests.java sub-tests failing due to JDK-8305414
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[mlbridge]

Mailing list message from Patrick Chen on build-dev:

lgtm

Le lun. 27 f?vr. 2023 ? 17:17, Jayathirth D V <jdv at openjdk.org> a ?crit :

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[mrserb]

When I mention that option in the JBS, I meant that we should take a look on how the methods in the library are "packed" since for some reason "-fpic" make some difference, probably we should use "static" more often or something like that. It is better to check what is the actual difference in the generated/packed code.

[jayathirthrao]

When I mention that option in the JBS, I meant that we should take a look on how the methods in the library are "packed" since for some reason "-fpic" make some difference, probably we should use "static" more often or something like that. It is better to check what is the actual difference in the generated/packed code.

Thanks @mrserb for clarification. I will get back with more details.

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