Messages in this thread | | | Date | Mon, 19 Sep 2022 07:34:02 -1000 | From | Tejun Heo <> | Subject | Re: [PATCH v4 6/8] sched/fair: Add sched group latency support |
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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?
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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