Commit 92a801e5 authored Nov 05, 2018 by Patrick Bellasi Committed by Ingo Molnar Nov 12, 2018

sched/fair: Mask UTIL_AVG_UNCHANGED usages



The _task_util_est() is mainly used to add/remove the task contribution
to/from the rq's estimated utilization at task enqueue/dequeue time.
In both cases we ensure the UTIL_AVG_UNCHANGED flag is set to keep
consistency between enqueue and dequeue time while still being
transparent to update_load_avg calls which will eventually reset the
flag.

Let's move the flag forcing within _task_util_est() itself so that we
can simplify calling code by hiding that estimated utilization
implementation detail into one of its internal functions.

This will affect also the "public" API task_util_est() but we know that
the flag will (eventually) impact just on the LSB of the estimated
utilization, thus it's certainly acceptable.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20181105145400.935-3-patrick.bellasi@arm.com


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

parent 59e1678c

kernel/sched/fair.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -3604,7 +3604,7 @@ static inline unsigned long _task_util_est(struct task_struct *p)
		{
		struct util_est ue = READ_ONCE(p->se.avg.util_est);

		return max(ue.ewma, ue.enqueued);
		return (max(ue.ewma, ue.enqueued) \| UTIL_AVG_UNCHANGED);
		}

		static inline unsigned long task_util_est(struct task_struct *p)
		@@ -3622,7 +3622,7 @@ static inline void util_est_enqueue(struct cfs_rq *cfs_rq,

		/* Update root cfs_rq's estimated utilization */
		enqueued = cfs_rq->avg.util_est.enqueued;
		enqueued += (_task_util_est(p) \| UTIL_AVG_UNCHANGED);
		enqueued += _task_util_est(p);
		WRITE_ONCE(cfs_rq->avg.util_est.enqueued, enqueued);
		}

		@@ -3650,8 +3650,7 @@ util_est_dequeue(struct cfs_rq cfs_rq, struct task_struct p, bool task_sleep)

		/* Update root cfs_rq's estimated utilization */
		ue.enqueued = cfs_rq->avg.util_est.enqueued;
		ue.enqueued -= min_t(unsigned int, ue.enqueued,
		(_task_util_est(p) \| UTIL_AVG_UNCHANGED));
		ue.enqueued -= min_t(unsigned int, ue.enqueued, _task_util_est(p));
		WRITE_ONCE(cfs_rq->avg.util_est.enqueued, ue.enqueued);

		/*
		@@ -6292,7 +6291,7 @@ static unsigned long cpu_util_without(int cpu, struct task_struct *p)
		*/
		if (unlikely(task_on_rq_queued(p) \|\| current == p)) {
		estimated -= min_t(unsigned int, estimated,
		(_task_util_est(p) \| UTIL_AVG_UNCHANGED));
		_task_util_est(p));
		}
		util = max(util, estimated);
		}

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