8350596: [Linux] Increase default MaxRAMPercentage for containerized workloads

[jerboaa]

Please take a look at this proposal to fix the "Java needs so much memory" perception in containers. The idea would be to bump the default MaxRAMPercentage to a higher value. The patch proposes 75%, but we could just as well use 50% if people feel more comfortable about it. Right now the default deployment in containers with resource limits in place (common for Kubernetes deployments) where a single process runs in the container isn't well catered for today for an application that just uses the default configuration. Only 25% of the container memory will be used for the Java heap, arguably wasting much of the remaining memory that has been granted to the container by a memory limit (that the JVM would detect and use as physical memory).

I've filed a CSR for this as well for which I'm looking for reviewers too and intend to write a release note as well about this change as it has some risk associated with it, although the escape hatch is pretty simple: set -XX:MaxRAMPercentage=25.0 to go back to the old behavour.

Testing:

• GHA - tier 1 (windows failures seem infra related)
• hotspot and jdk container tests on cg v2 and cg v1 including the two new tests.

Thoughts? Opinions?

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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-8356194 to be approved

Issues

• JDK-8350596: [Linux] Increase default MaxRAMPercentage for containerized workloads (Enhancement - P3)
• JDK-8356194: [Linux] Increase default MaxRAMPercentage for containerized workloads (CSR)

Reviewing

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[bridgekeeper]

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[jerboaa]

/label add hospot-gc-dev

[jerboaa]

/csr needed

[openjdk]

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[openjdk]

@jerboaa
The label hospot-gc is not a valid label.
These labels are valid:

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[openjdk]

@jerboaa an approved CSR request is already required for this pull request.

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[mlbridge]

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[jerboaa]

/label add hotspot-gc

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@jerboaa
The hotspot-gc label was successfully added.