RFR: 8300658: memory_and_swap_limit() reporting wrong values on systems with swapaccount=0 [v5]

[Severin Gehwolf]

On Fri, 17 Feb 2023 13:17:20 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Please review this change which brings the hotspot code up to date with how the Java metrics behave. On a system where swap accounting is disabled `VM.info` jcmd - for example - no longer reports an unsupported metric, but the memory limit instead as that is actually what is being in place.
>> 
>> I had to update the `TestMemoryWithCgroupV1.java` test as it skipped the swappiness testing based on the now gone output.
>> 
>> Testing:
>> - [x] Linux container tests on cg1 and cg2 with and without swap accounting.
>> - [x] New regression test fails on unpatched systems with `swapaccount=0` kernel option. Passes after.
>> - [x] GHA (linux tier1 failure is unrelated).
>> 
>> Thoughts?
>
> Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use utility function for reading swap.

Thanks for the reviews!

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PR: https://git.openjdk.org/jdk/pull/12262