Messages in this thread | | | From | Vincent Guittot <> | Date | Tue, 20 Sep 2022 09:02:54 +0200 | Subject | Re: [PATCH v4 6/8] sched/fair: Add sched group latency support |
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On Mon, 19 Sept 2022 at 19:34, Tejun Heo <tj@kernel.org> wrote: > > Hello, > > On Mon, Sep 19, 2022 at 01:55:15PM +0200, Dietmar Eggemann wrote: > > s/valentin.schneider@arm.com// > > > > On 16/09/2022 10:03, Vincent Guittot wrote: > > > Task can set its latency priority, which is then used to decide to preempt > > > the current running entity of the cfs, but sched group entities still have > > > the default latency offset. > > > > > > Add a latency field in task group to set the latency offset of the > > > sched_eneities of the group, which will be used against other entities in > > > > s/sched_eneities/sched_entity > > > > > the parent cfs when deciding which entity to schedule first. > > > > So latency for cgroups does not follow any (existing) Resource > > Distribution Model/Scheme (Documentation/admin-guide/cgroup-v2.rst)? > > Latency values are only used to compare sched entities at the same level. > > I think it'd still result in a hierarchical behavior as scheduling is done > recursively top-down. Right, vincent?
Correct
> > It doesn't fit any of the resource distribution model. But it's rather > difficult to map latencies to existing concepts of resources and we have a > precedence in the cpu controller (.idle) which behaves similarly, so as long > as the behavior is hierarchical, I think it's okay. > > Thanks. > > -- > tejun
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