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List:       openjdk-2d-dev
Subject:    Re: RFR: 8301869: Regression ~14% in J2dBench-bimg_misc-* in 21-b5 only on linux-aarch64 [v3]
From:       Sergey Bylokhov <serb () openjdk ! org>
Date:       2023-02-28 23:58:04
Message-ID: T1p4rkxace2Uaz5Wvomf0AtmF72jECF3VSvrqaCIvTU=.121b6add-b62f-4cb5-89cd-8f5bb820752b () github ! com
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On Tue, 28 Feb 2023 06:55:36 GMT, Jayathirth D V <jdv@openjdk.org> wrote:

> > 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.
> 
> Jayathirth D V has updated the pull request incrementally with one additional \
> commit since the last revision: 
> Shift comment

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.

-------------

PR: https://git.openjdk.org/jdk/pull/12761


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