8371986: Remove the default value of InitialRAMPercentage

[jsikstro]

Hello,

This RFE changes the default of InitialRAMPercentage to 0, effectively removing its default value. Please see the CSR for specific details on this change.

Changing the default value to 0 results in the behavior that the initial heap size (InitialHeapSize) is set to the minimum heap size (MinHeapSize). This is because of the following lines in Arguments::set_heap_size(), which takes the MAX value of MinHeapSize as well:

uint64_t initial_memory = (uint64_t)(((double)MaxRAM * InitialRAMPercentage) / 100);
...

reasonable_initial = MAX3(reasonable_initial, reasonable_minimum, MinHeapSize);
reasonable_initial = MIN2(reasonable_initial, MaxHeapSize);

This change improves startup performance for all GCs, but affects the time-to-peak performance in some out-of-the-box configurations for some GCs. This is mainly visible in ParallelGC.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change requires CSR request JDK-8371987 to be approved

Issues

• JDK-8371986: Remove the default value of InitialRAMPercentage (Enhancement - P4)
• JDK-8371987: Remove the default value of InitialRAMPercentage (CSR)

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)
• Axel Boldt-Christmas (@xmas92 - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

@jsikstro This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8371986: Remove the default value of InitialRAMPercentage

Reviewed-by: shade, aboldtch

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At the time when this comment was updated there had been 12 new commits pushed to the master branch:

• 0c6d1b9: 8371759: Add missing @OverRide annotations in com.sun.imageio package
• 195b36f: 8372702: sun/security/pkcs11/tls/fips/FipsModeTLS.java does not compile after JDK-8367096
• f1d90b8: 8372134: ThreadLocalRandom no longer overrides nextGaussian
• ... and 9 more: https://git.openjdk.org/jdk/compare/4ac33956343bbfa3619ccb029ceed6c5a402f775...master

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[openjdk]

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[mlbridge]

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[jsikstro]

/label remove graal

[openjdk]

@jsikstro
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