Commit b462b2ec authored Aug 05, 2019 by Jonathan Avila

Revert "sched/fair: correct fastpath"



This reverts commit 258cafe4. This change
was primarily done to avoid long exit idle times on mid capacity CPUs. A
task would be assigned a busy mid cap CPU if the idle one were in a deeper
idle state.

This change made sense in theory, but queueing on a busy CPU is seen to
take longer for the tasks to complete. Assigning a task to an idle CPU and
taking the idle exit latency hit has proven to be less of a bottleneck.

Change-Id: I50b27d089db4226a015e1cae6ba28c8fd4172f0c
Signed-off-by: Jonathan Avila <avilaj@codeaurora.org>

parent dac6e981

kernel/sched/fair.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -6851,9 +6851,7 @@ static void find_best_target(struct sched_domain sd, cpumask_t cpus,
		!cpu_isolated(prev_cpu) && cpu_online(prev_cpu) &&
		idle_cpu(prev_cpu)) {

		if (idle_get_state_idx(cpu_rq(prev_cpu)) <=
		(is_min_capacity_cpu(prev_cpu) ? 1 : 0)) {

		if (idle_get_state_idx(cpu_rq(prev_cpu)) <= 1) {
		target_cpu = prev_cpu;

		fbt_env->fastpath = PREV_CPU_FASTPATH;