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sched: Simplify wake_up_*idle*() 

Simplify and make wake_up_if_idle() more robust, also don't iterate
the whole machine with preempt_disable() in it's caller:
wake_up_all_idle_cpus().

This prepares for another wake_up_if_idle() user that needs a full
do_idle() cycle.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com> # on s390
Link: https://lkml.kernel.org/r/20210929152428.769328779@infradead.org
This commit is contained in:
Peter Zijlstra 2021-09-21 22:16:02 +02:00
parent 00619f7c65
commit 8850cb663b
2 changed files with 8 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
kernel/sched/core.c
View File

@ -3695,15 +3695,11 @@ void wake_up_if_idle(int cpu)
if (!is_idle_task(rcu_dereference(rq->curr)))
goto out;
if (set_nr_if_polling(rq->idle)) {
trace_sched_wake_idle_without_ipi(cpu);
} else {
rq_lock_irqsave(rq, &rf);
if (is_idle_task(rq->curr))
smp_send_reschedule(cpu);
/* Else CPU is not idle, do nothing here: */
rq_unlock_irqrestore(rq, &rf);
}
rq_lock_irqsave(rq, &rf);
if (is_idle_task(rq->curr))
resched_curr(rq);
/* Else CPU is not idle, do nothing here: */
rq_unlock_irqrestore(rq, &rf);
out:
rcu_read_unlock();

6
kernel/smp.c
View File

@ -1170,14 +1170,14 @@ void wake_up_all_idle_cpus(void)
{
int cpu;
preempt_disable();
cpus_read_lock();
for_each_online_cpu(cpu) {
if (cpu == smp_processor_id())
if (cpu == raw_smp_processor_id())
continue;
wake_up_if_idle(cpu);
}
preempt_enable();
cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);