Messages in this thread | | | Date | Mon, 10 Jul 2023 23:24:37 -0400 | Subject | Re: [PATCH v4 8/9] cgroup/cpuset: Documentation update for partition | From | Waiman Long <> |
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On 7/10/23 21:07, Tejun Heo wrote: > Hello, > > On Mon, Jul 10, 2023 at 08:53:18PM -0400, Waiman Long wrote: >> For local partition, it doesn't make sense to have a cpust.cpus.exclusive >> that is not the same as cpuset.cpus as it artificially reduce the set of >> CPUs that can be used in a partition. In the case of a remote partition, the > Yeah, I was wondering about local partitions. "Automatic but can be > overridden" behavior becomes confusing if it's difficult for the user to > easily tell which part is automatic when. I wonder whether it'd be better to > make the condition static - e.g. for a partition cgroup, cpus.exclusive > always contains all bits in cpus no matter what value is written to it. Or, > if we separate out cpus.exclusive and cpus.exclusive.effective, no matter > what cpus.exclusive is set, a partition root's cpus.exclusive.effective > always includes all bits in cpus.effective.
With no offline CPUs, cpus.effective should be the same as cpus.exclusive.effective for a valid partition root. Here cpus.exclusive.effective is a bit different from cpus.effective as it can contain offline cpus. It also mean that adding cpus.exclusive.effective can be redundant.
As said before, I try to avoid adding new cpuset control file unless absolutely necessary. I now have a slight different proposal. Once manually set, I can keep cpuset.cpus.exclusive invariant. I do need to do a bit more work when enabling a partition root to find out the effective set of exclusive CPUs to be used or make the partition invalid if no exclusive CPU is available. I still want to do a initial check when setting cpuset.cpus.exclusive to make sure that the value is at least valid at the beginning.
Do you think this is an acceptable compromise?
Thanks, Longman
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