RFR: 8322420: [Linux] cgroup v2: Limits in parent nested control groups are not detected [v15]

[Jan Kratochvil]

On Mon, 22 Jul 2024 13:48:29 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Jan Kratochvil has refreshed the contents of this pull request, and previous commits have been removed. Incremental views are not available.
>
> test/hotspot/jtreg/containers/cgroup/NestedCgroup.java line 193:
> 
>> 191:         }
>> 192:     }
>> 193:     private static class TestNoController extends Test {
> 
> This logic doesn't seem to detect `cgv1` and `cgv2` correctly. When I run this on a cgv1 system (hybrid) then I get a failure that looks like this:
> 
> 
> ----------System.err:(33/2506)----------
> -------------------------------------------------------------------------------- command: cgdelete -r -g memory:jdktest150899
> -------------------------------------------------------------------------------- stdout
> -------------------------------------------------------------------------------- stderr
> cgdelete: cannot remove group 'jdktest150899': No such file or directory
> --------------------------------------------------------------------------------
> -------------------------------------------------------------------------------- command: cgcreate -g memory:jdktest150899/inner
> -------------------------------------------------------------------------------- stdout
> -------------------------------------------------------------------------------- stderr
> --------------------------------------------------------------------------------
> isCgroup2 = true
> -------------------------------------------------------------------------------- cgroup2 mount point: /sys/fs/cgroup/unified
> java.nio.file.NoSuchFileException: /sys/fs/cgroup/unified/jdktest150899/memory.max
>         at java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:92)
>         at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:106)
>         at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
>         at java.base/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:262)
>         at java.base/java.nio.file.spi.FileSystemProvider.newOutputStream(FileSystemProvider.java:482)
>         at java.base/java.nio.file.Files.newOutputStream(Files.java:228)
>         at java.base/java.nio.file.Files.write(Files.java:3516)
>         at java.base/java.nio.file.Files.writeString(Files.java:3738)
>         at java.base/java.nio.file.Files.writeString(Files.java:3678)
>         at NestedCgroup$Test.<init>(NestedCgroup.java:161)
>         at NestedCgroup$TestTwoLimits.<init>(NestedCgroup.java:190)
>         at NestedCgroup.main(NestedCgroup.java:221)
>         at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
>         at java.base/java.lang.r...

I have used `Metrics.systemMetrics()`. But it still needs to parse `Metrics.systemMetrics()` to find out the mount point (`sysFsCgroup`) to write into the `memory.max` file. I have tried to combine both. Please tell me if it works or not on your system.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/17198#discussion_r1695317939