RFR: 8322420: [Linux] cgroup v2: Limits in parent nested control groups are not detected [v2]

[Zdenek Zambersky]

On Tue, 27 Aug 2024 19:42:14 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Hi @jerboaa,
>> 
>> Had a look. I am no expert in these things, so this concentrates more on the mechanical parts and on readability.
>> 
>> Cheers, Thomas
>
>> Had a look. I am no expert in these things, so this concentrates more on the mechanical parts and on readability.
> 
> Thanks very much for the review, @tstuefe!

Hi @jerboaa,
New approach is nice improvement. Going up the hierarchy until reaching some limit should probably work ok for real word cases. It has its limitations though. Namely the case, when there is a stricter limit higher in the hierarchy. E.g. if I do:

$ cat /etc/systemd/system/user.slice.d/memory-limit.conf
[Slice]
MemoryLimit=512M
$ sudo systemctl daemon-reload

than JDK will pick limit from `user-cg.slice` (following your example) rather than from `user.slice` (even though stricter limit from user.slice is actually in force). This may be known limitation (based on description). Scenario is probably uncommon in real world.

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PR Comment: https://git.openjdk.org/jdk/pull/20646#issuecomment-2315263792