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Commit fd2ac4f4 authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

nohz: Use nohz own full kick on 2nd task enqueue 



Now that we have a nohz full remote kick based on irq work, lets use
it to notify a CPU that it's exiting single task mode.

This unbloats a bit the scheduler IPI that the nohz code was abusing
for its cool "callable anywhere/anytime" properties.

Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 53c5fa16

kernel/sched/core.c

+1 −4
Original line number Diff line number Diff line
@@ -1574,9 +1574,7 @@ void scheduler_ipi(void) 
	 */

	preempt_fold_need_resched();



	if (llist_empty(&this_rq()->wake_list)

			&& !tick_nohz_full_cpu(smp_processor_id())

			&& !got_nohz_idle_kick())

	if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())

		return;



	/*
@@ -1593,7 +1591,6 @@ void scheduler_ipi(void) 
	 * somewhat pessimize the simple resched case.

	 */

	irq_enter();

	tick_nohz_full_check();

	sched_ttwu_pending();



	/*

kernel/sched/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -1223,7 +1223,7 @@ static inline void add_nr_running(struct rq *rq, unsigned count) 
		if (tick_nohz_full_cpu(rq->cpu)) {

			/* Order rq->nr_running write against the IPI */

			smp_wmb();

			smp_send_reschedule(rq->cpu);

			tick_nohz_full_kick_cpu(rq->cpu);

		}

       }

#endif