8374045: Add support to run benchmarking with fragmented CodeCache

[chadrako]

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.

This is useful to show the performance benefits of JDK-8326205

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Progress

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Issue

• JDK-8374045: Add support to run benchmarking with fragmented CodeCache (Enhancement - P4)

Reviewing

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Update a local copy of the PR:
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[openjdk]

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[openjdk]

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Applicable Labels

• build
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• hotspot-gc
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• jmx
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[chadrako]

/label add tools

[openjdk]

@chadrako
The label tools is not a valid label.
These labels are valid:

• serviceability
• hotspot
• hotspot-compiler
• ide-support
• i18n
• shenandoah
• jdk
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• security
• hotspot-runtime
• jmx
• build
• nio
• client
• core-libs
• compiler
• net
• hotspot-gc
• hotspot-jfr

[chadrako]

/label add compiler

[openjdk]

@chadrako
The compiler label was successfully added.