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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: Peter 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: Frederic Weisbecker <fweisbec@gmail.com>
hifive-unleashed-5.1
Frederic Weisbecker 2014-03-18 21:12:53 +01:00
parent 53c5fa16b4
commit fd2ac4f4a6
2 changed files with 2 additions and 5 deletions
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5
kernel/sched/core.c
View File

@ -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();
/*

2
kernel/sched/sched.h
View File

@ -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