Commit aa3ee4f0 authored by Xuewen Yan's avatar Xuewen Yan Committed by Peter Zijlstra
Browse files

sched/fair: Fixup wake_up_sync() vs DELAYED_DEQUEUE 



Delayed dequeued feature keeps a sleeping task enqueued until its
lag has elapsed. As a result, it stays also visible in rq->nr_running.
So when in wake_affine_idle(), we should use the real running-tasks
in rq to check whether we should place the wake-up task to
current cpu.
On the other hand, add a helper function to return the nr-delayed.

Fixes: 152e11f6 ("sched/fair: Implement delayed dequeue")
Signed-off-by: default avatarXuewen Yan <xuewen.yan@unisoc.com>
Reviewed-and-tested-by: default avatarTianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250303105241.17251-2-xuewen.yan@unisoc.com
parent 676e8cf7

kernel/sched/fair.c

+11 −2
Original line number Diff line number Diff line
@@ -7193,6 +7193,11 @@ static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	return true;

}



static inline unsigned int cfs_h_nr_delayed(struct rq *rq)

{

	return (rq->cfs.h_nr_queued - rq->cfs.h_nr_runnable);

}



#ifdef CONFIG_SMP



/* Working cpumask for: sched_balance_rq(), sched_balance_newidle(). */
@@ -7354,8 +7359,12 @@ wake_affine_idle(int this_cpu, int prev_cpu, int sync) 
	if (available_idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))

		return available_idle_cpu(prev_cpu) ? prev_cpu : this_cpu;



	if (sync && cpu_rq(this_cpu)->nr_running == 1)

	if (sync) {

		struct rq *rq = cpu_rq(this_cpu);



		if ((rq->nr_running - cfs_h_nr_delayed(rq)) == 1)

			return this_cpu;

	}



	if (available_idle_cpu(prev_cpu))

		return prev_cpu;