[jdk11u-dev] RFR: JDK-8306768: CodeCache Analytics reports wrong threshold

[Tobias Hartmann]

On Mon, 24 Apr 2023 17:19:30 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

> Jcmd CodeCache_Analytics uses own implementation of threshold calculation, allowing an error to creep in, making report invalid. The suggestion is to use the existing method for free ratio calculation. After the fix, the reported values become sane.
> 
> 
> java -XX:InitialCodeCacheSize=1G -XX:ReservedCodeCacheSize=1G ...
> 
> cmd jdk.compiler/com.sun.tools.javac.launcher.Main  Compiler.CodeHeap_Analytics | grep -A 2 "Threshold for method to be considered 'cold'"
> Threshold for method to be considered 'cold':    -2037.994
> min. hotness =   1016
> avg. hotness =   2048
> --
> Threshold for method to be considered 'cold':    -2037.961
> min. hotness =   1016
> avg. hotness =   2048
> --
> Threshold for method to be considered 'cold':    -2031.906
> No hotness data available

Shouldn't we fix this in JDK 17u and then backport to JDK 11u?

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PR Comment: https://git.openjdk.org/jdk11u-dev/pull/1849#issuecomment-1521358310