SapMachine #2137: Linux: We should use transparent huge pages in some configurations

[TheRealMDoerr]

Enable UseTransparentHugePages by default if the machine and JVM configuration are suited for their usage. Some tests need a small adaptation to support that.

fixes #2137

[SapMachine]

Hello @TheRealMDoerr, this pull request fulfills all formal requirements.

[SapMachine]

Hello @TheRealMDoerr, this pull request fulfills all formal requirements.

[RealCLanger]

I think this looks good but I'm wondering whether it's possible to do the changes to the tests in OpenJDK? It should not be wrong there, no?

[dbriemann]

👍

[TheRealMDoerr]

I think this looks good but I'm wondering whether it's possible to do the changes to the tests in OpenJDK? It should not be wrong there, no?

I would like to have them in OpenJDK because they do no harm. However, I don't have any justification for such changes without changing the default of UseTransparentHugePages. Note that these tests use @requires vm.flagless.

[MBaesken]

java.md mentions UseTransparentHugePages

https://github.com/openjdk/jdk/blob/692edc4879489d44a477a03028eb3e7ef9dff388/src/java.base/share/man/java.md?plain=1#L1579

Seems what is said is not true now any more for SapMachine; not sure how important it is but might be better to adjust (of course in SapMachine) ?

[SapMachine]

Hello @TheRealMDoerr, this pull request fulfills all formal requirements.

[RealCLanger]

I think this looks good but I'm wondering whether it's possible to do the changes to the tests in OpenJDK? It should not be wrong there, no?

I would like to have them in OpenJDK because they do no harm. However, I don't have any justification for such changes without changing the default of UseTransparentHugePages. Note that these tests use @requires vm.flagless.

Yes, I see your point, it's hard to motivate in OpenJDK, I guess.