Messages in this thread | | | Date | Tue, 31 May 2022 10:21:03 -0400 | Subject | Re: [RFC PATCH 4/4] cpuset: Support RCU-NOCB toggle on v2 root partitions | From | Waiman Long <> |
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On 5/30/22 09:16, Peter Zijlstra wrote: > On Mon, May 30, 2022 at 12:56:50PM +0200, Frederic Weisbecker wrote: > >>> This is ABI, you can't walk back on it. I would suggest starting with an >>> 'all feature' isolation. Only if there's real demand for something more >>> fine-grained add that on top. Simple first etc. >> That's actually my worry. If we start with an all in one ABI, how do we later >> mix that up with more finegrained features? Like what will be the behaviour of: >> >> cpuset.isolation.rcu_nocb = 0 >> cpuset.isolation.all = 1 > Well clearly that doesn't make sense. I was more thinking along the > lines of cgroup.subtree_control, where instead all features are enabled > by default. > > But only if there's a real usecase, otherwise there's no point in > providing such knobs.
I am actually thinking about extending the cpuset partition interface for isolation. Right now, I have an outstanding patch [1] to add an "isolated" state to partition which disable load balancing somewhat similar to isolcpus command line option. In the future, we can add attribute to the isolation state like "isolated:full" to similar to nohz_full currently. If the needs arise, we can even extend the attribute to allow list like "isolated:rcu_nocbs". I don't think it is good idea to keep on adding new cpuset control files extensively. I would prefer extending the existing ones.
[1] https://lore.kernel.org/lkml/20220510153413.400020-1-longman@redhat.com/
Cheers, Longman
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