Messages in this thread |  | | Date | Wed, 12 Oct 2022 15:22:48 +0100 | From | Qais Yousef <> | Subject | Re: [PATCH v5 5/7] sched/fair: Add sched group latency support |
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On 09/25/22 16:39, Vincent Guittot wrote: > Task can set its latency priority with sched_setattr(), which is then used > to set the latency offset of its sched_entity, but sched group entities > still have the default latency offset value. > > Add a latency.nice field in cpu cgroup controller to set the latency > priority of the group similarly to sched_setattr(). The latency priority > is then used to set the offset of the sched_entities of the group. > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > Documentation/admin-guide/cgroup-v2.rst | 8 ++++ > kernel/sched/core.c | 53 +++++++++++++++++++++++++ > kernel/sched/fair.c | 33 +++++++++++++++ > kernel/sched/sched.h | 4 ++ > 4 files changed, 98 insertions(+) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index be4a77baf784..d8ae7e411f9c 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1095,6 +1095,14 @@ All time durations are in microseconds. > values similar to the sched_setattr(2). This maximum utilization > value is used to clamp the task specific maximum utilization clamp. > > + cpu.latency.nice > + A read-write single value file which exists on non-root > + cgroups. The default is "0". > + > + The nice value is in the range [-20, 19]. > + > + This interface file allows reading and setting latency using the > + same values used by sched_setattr(2).
I still don't understand how tasks will inherit the latency_nice value from cgroups they're attached to.
For example, in EAS path we operate at task level only. If the task's p->latency_nice = 0, but it belongs to a task group tg->latency_nice = -19; what should the task's latency_nice be in this case? If it's in a hierarchy, how would the effective value be calculated?
Thanks
-- Qais Yousef
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