Commit c829d681 authored by Shrikanth Hegde's avatar Shrikanth Hegde Committed by Ingo Molnar
Browse files

sched/fair: Simplify the continue_balancing logic in sched_balance_newidle() 



newidle(CPU_NEWLY_IDLE) balancing doesn't stop the load-balancing if the
continue_balancing flag is reset, but the other two balancing (IDLE, BUSY)
cases do that.

newidle balance stops the load balancing if rq has a task or there
is wakeup pending. The same checks are present in should_we_balance for
newidle. Hence use the return value and simplify continue_balancing
mechanism for newidle. Update the comment surrounding it as well.

No change in functionality intended.

Signed-off-by: default avatarShrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20240325153926.274284-1-sshegde@linux.ibm.com
parent d0f5d3ce

kernel/sched/fair.c

+5 −5
Original line number Diff line number Diff line
@@ -12358,6 +12358,7 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) 
{

	unsigned long next_balance = jiffies + HZ;

	int this_cpu = this_rq->cpu;

	int continue_balancing = 1;

	u64 t0, t1, curr_cost = 0;

	struct sched_domain *sd;

	int pulled_task = 0;
@@ -12372,8 +12373,9 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) 
		return 0;



	/*

	 * We must set idle_stamp _before_ calling idle_balance(), such that we

	 * measure the duration of idle_balance() as idle time.

	 * We must set idle_stamp _before_ calling sched_balance_rq()

	 * for CPU_NEWLY_IDLE, such that we measure the this duration

	 * as idle time.

	 */

	this_rq->idle_stamp = rq_clock(this_rq);
@@ -12412,7 +12414,6 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) 


	rcu_read_lock();

	for_each_domain(this_cpu, sd) {

		int continue_balancing = 1;

		u64 domain_cost;



		update_next_balance(sd, &next_balance);
@@ -12438,8 +12439,7 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) 
		 * Stop searching for tasks to pull if there are

		 * now runnable tasks on this rq.

		 */

		if (pulled_task || this_rq->nr_running > 0 ||

		    this_rq->ttwu_pending)

		if (pulled_task || !continue_balancing)

			break;

	}

	rcu_read_unlock();