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Commit 4fed24d1 authored Apr 13, 2016 by Pavankumar Kondeti Committed by Gerrit - the friendly Code Review server Mar 24, 2017

sched: don't assume higher capacity means higher power in tick migration



When an upmigrate ineligible task running on the maximum capacity CPU,
we check if it can be migrated to a lower capacity CPU in tick path.
Add a power cost based check there to prevent the task migration
from a power efficient CPU.

Change-Id: I291c62d7dbf169d5123faba5f5246ad44a7a40dd
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>

parent 52296641

kernel/sched/fair.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -11380,8 +11380,15 @@ static inline int migration_needed(struct task_struct *p, int cpu)
		nice = task_nice(p);
		rcu_read_lock();
		grp = task_related_thread_group(p);
		/*
		* Don't assume higher capacity means higher power. If the task
		* is running on the power efficient CPU, avoid migrating it
		* to a lower capacity cluster.
		*/
		if (!grp && (nice > SCHED_UPMIGRATE_MIN_NICE \|\|
		upmigrate_discouraged(p)) && cpu_capacity(cpu) > min_capacity) {
		upmigrate_discouraged(p)) &&
		cpu_capacity(cpu) > min_capacity &&
		cpu_max_power_cost(cpu) == max_power_cost) {
		rcu_read_unlock();
		return DOWN_MIGRATION;
		}

kernel/sched/hmp.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -454,6 +454,12 @@ compare_clusters(void priv, struct list_head a, struct list_head *b)
		cluster1 = container_of(a, struct sched_cluster, list);
		cluster2 = container_of(b, struct sched_cluster, list);

		/*
		* Don't assume higher capacity means higher power. If the
		* power cost is same, sort the higher capacity cluster before
		* the lower capacity cluster to start placing the tasks
		* on the higher capacity cluster.
		*/
		ret = cluster1->max_power_cost > cluster2->max_power_cost \|\|
		(cluster1->max_power_cost == cluster2->max_power_cost &&
		cluster1->max_possible_capacity <