On Fri, 19 Dec 2025 20:08:20 GMT, Chad Rakoczy <[email protected]> wrote:
> [JDK-8374045](https://bugs.openjdk.org/browse/JDK-8374045) > > This PR adds a new utility tool CodeCacheFragmenter to help with testing > HotSpot code cache fragmentation scenarios. The tool is a Java agent that > uses the WhiteBox API to create and randomly free dummy code blobs in the > NonProfiled code heap to achieve a specified fill percentage. It includes > configurable parameters for blob sizes, target fill percentage (0-100%), and > random seeding to enable reproducible fragmentation patterns. The utility is > built via a standard Makefile and produces `codecachefragmenter.jar` which > can be used as a Java agent with `-javaagent` flag. This tool is intended for > performance testing and experimentation with code cache behavior under > various fragmentation conditions. The distribution of blob sizes aims to > represent real world nmethod sizes which are based on sizes from running > Renaissance benchmarks. > > This is useful to show the performance benefits of > [JDK-8326205](https://bugs.openjdk.org/browse/JDK-8326205) > > Distribution of nmethod size from Renaissance benchmarks: > <img width="3570" height="1766" alt="renaissance_dis" > src="https://github.com/user-attachments/assets/cde9645a-38d3-4506-811f-646ced78715a"; > /> > > Distribution of dummy blob size from CodeCacheFragmenter: > <img width="3570" height="1766" alt="frag_new_dis" > src="https://github.com/user-attachments/assets/2c61cc0d-20a8-4ae0-af42-8cfc98271217"; > /> This pull request has been closed without being integrated. ------------- PR: https://git.openjdk.org/jdk/pull/28934
