Messages in this thread | | | Date | Wed, 9 Jun 2021 14:37:04 +0000 | From | Quentin Perret <> | Subject | Re: [PATCH] sched: Fix UCLAMP_FLAG_IDLE setting |
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On Wednesday 09 Jun 2021 at 14:33:39 (+0000), Quentin Perret wrote: > The UCLAMP_FLAG_IDLE flag is set on a runqueue when dequeueing the last > active task to maintain the last uclamp.max and prevent blocked util > from suddenly becoming visible. > > However, there is an asymmetry in how the flag is set and cleared which > can lead to having the flag set whilst there are active task on the rq. > Specifically, the flag is set in the uclamp_rq_inc() path, which is > called at enqueue time, but cleared in the uclamp_rq_dec_id() which is > called both when dequeueing and task _and_ during cgroup migrations. > > Fix this by setting the flag in the uclamp_rq_inc_id() path to ensure > things remain symmetrical. > > Reported-by: Rick Yiu <rickyiu@google.com> > Signed-off-by: Quentin Perret <qperret@google.com>
Argh, and I think this wants
Fixes: e496187da710 ("sched/uclamp: Enforce last task's UCLAMP_MAX")
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