Commit a87498ac authored Jun 21, 2019 by Patrick Bellasi Committed by Ingo Molnar Jun 24, 2019

sched/uclamp: Reset uclamp values on RESET_ON_FORK



A forked tasks gets the same clamp values of its parent however, when
the RESET_ON_FORK flag is set on parent, e.g. via:

   sys_sched_setattr()
      sched_setattr()
         __sched_setscheduler(attr::SCHED_FLAG_RESET_ON_FORK)

the new forked task is expected to start with all attributes reset to
default values.

Do that for utilization clamp values too by checking the reset request
from the existing uclamp_fork() call which already provides the required
initialization for other uclamp related bits.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-8-patrick.bellasi@arm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent a509a7cd

kernel/sched/core.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1082,6 +1082,14 @@ static void uclamp_fork(struct task_struct *p)

		for_each_clamp_id(clamp_id)
		p->uclamp[clamp_id].active = false;

		if (likely(!p->sched_reset_on_fork))
		return;

		for_each_clamp_id(clamp_id) {
		uclamp_se_set(&p->uclamp_req[clamp_id],
		uclamp_none(clamp_id), false);
		}
		}

		static void __init init_uclamp(void)

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