[jdk11u-dev] RFR: 8302191: Performance degradation for float/double modulo on Linux

[Paul Hohensee]

On Tue, 4 Apr 2023 13:00:13 GMT, Jan Kratochvil <duke at openjdk.org> wrote:

> Backport of [JDK-8302191](https://bugs.openjdk.java.net/browse/JDK-8302191). Applies cleanly. It is already committed in trunk.
> 
> 
> build/linux-x86_64-normal-server-fastdebug/jdk/bin/java -jar ~/azul/jmh-jdk-microbenchmarks-git/micros-jdk8/target/micros-jdk8-1.0-SNAPSHOT.jar org.openjdk.bench.java.lang.FloatDoubleRem -i 2 -r 2 -wi 2 -f 2
> unpatched:
> Benchmark                            Mode  Cnt    Score    Error  Units
> FloatDoubleRem.calcDoubleJava        avgt    4  103.219 ±  4.637  ns/op
> FloatDoubleRem.calcFloatJava         avgt    4  106.588 ± 10.357  ns/op
> FloatDoubleRem.cornercaseDoubleJava  avgt    4   11.822 ±  4.074  ns/op
> FloatDoubleRem.cornercaseFloatJava   avgt    4   11.435 ±  1.355  ns/op
> patched:
> Benchmark                            Mode  Cnt   Score    Error  Units
> FloatDoubleRem.calcDoubleJava        avgt    4  34.712 ± 22.532  ns/op
> FloatDoubleRem.calcFloatJava         avgt    4  23.942 ±  5.177  ns/op
> FloatDoubleRem.cornercaseDoubleJava  avgt    4   8.080 ±  1.004  ns/op
> FloatDoubleRem.cornercaseFloatJava   avgt    4  10.647 ±  0.545  ns/op

11u is in maintenance mode, so this backport being purely a performance improvement will be unlikely to be approved by a Maintainer.

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PR Comment: https://git.openjdk.org/jdk11u-dev/pull/1824#issuecomment-1499553053