RFR: 8347129: cpuset cgroups controller is required for no good reason

[Ashutosh Mehra]

On Tue, 14 Jan 2025 16:58:08 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Thanks for the review!
>
>> @jerboaa Should this block be updated to not return false as the cpuset is now an optional subsystem.
>> 
>> https://github.com/openjdk/jdk/blob/56c780078f84a2571b779d90f528d5bcab2a9dfd/src/hotspot/os/linux/cgroupSubsystem_linux.cpp#L498-L503
> 
> @ashu-mehra Thanks for looking at it!
> 
> I'm in two minds about this. Why? a) cgroups v1 is becoming increasingly legacy b) the chance that an old v1 system would no longer enable cpusets controller seems unlikely. So while it seems consistent to remove this for cg v1 too, it's unlikely that such a system exists. For example Fedora 41 where this has been observed no longer supports cg v1. I'd expect for other distros to follow. New distros will likely only support cg v2.
> 
> For those reasons I'd be inclined to keep the patch as-is as it would be less risky for the cg v1 version.
> 
> Thoughts?

@jerboaa Thanks for the explanation. I agree with you. I think its fine to keep cg v1 as is.

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PR Comment: https://git.openjdk.org/jdk/pull/23037#issuecomment-2590716142