Commit 9e9af819 authored by Vincent Guittot's avatar Vincent Guittot Committed by Peter Zijlstra
Browse files

sched/fair: Account update_blocked_averages in newidle_balance cost 



The time spent to update the blocked load can be significant depending of
the complexity fo the cgroup hierarchy. Take this time into account in
the cost of the 1st load balance of a newly idle cpu.

Also reduce the number of call to sched_clock_cpu() and track more actual
work.

Signed-off-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: default avatarMel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20211019123537.17146-2-vincent.guittot@linaro.org
parent 5d1ceb39

kernel/sched/fair.c

+7 −4
Original line number Diff line number Diff line
@@ -10840,9 +10840,9 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) 
{

	unsigned long next_balance = jiffies + HZ;

	int this_cpu = this_rq->cpu;

	u64 t0, t1, curr_cost = 0;

	struct sched_domain *sd;

	int pulled_task = 0;

	u64 curr_cost = 0;



	update_misfit_status(NULL, this_rq);
@@ -10887,11 +10887,13 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) 


	raw_spin_rq_unlock(this_rq);



	t0 = sched_clock_cpu(this_cpu);

	update_blocked_averages(this_cpu);



	rcu_read_lock();

	for_each_domain(this_cpu, sd) {

		int continue_balancing = 1;

		u64 t0, domain_cost;

		u64 domain_cost;



		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {

			update_next_balance(sd, &next_balance);
@@ -10899,17 +10901,18 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) 
		}



		if (sd->flags & SD_BALANCE_NEWIDLE) {

			t0 = sched_clock_cpu(this_cpu);



			pulled_task = load_balance(this_cpu, this_rq,

						   sd, CPU_NEWLY_IDLE,

						   &continue_balancing);



			domain_cost = sched_clock_cpu(this_cpu) - t0;

			t1 = sched_clock_cpu(this_cpu);

			domain_cost = t1 - t0;

			if (domain_cost > sd->max_newidle_lb_cost)

				sd->max_newidle_lb_cost = domain_cost;



			curr_cost += domain_cost;

			t0 = t1;

		}



		update_next_balance(sd, &next_balance);