lkml.org 
[lkml]   [2021]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: sched/core] sched: Simplify wake_up_*idle*()
The following commit has been merged into the sched/core branch of tip:

Commit-ID: 8850cb663b5cda04d33f9cfbc38889d73d3c8e24
Gitweb: https://git.kernel.org/tip/8850cb663b5cda04d33f9cfbc38889d73d3c8e24
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Tue, 21 Sep 2021 22:16:02 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 07 Oct 2021 13:51:15 +02:00

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
---
kernel/sched/core.c | 14 +++++---------
kernel/smp.c | 6 +++---
2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 74db3c3..3b55ef9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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();
diff --git a/kernel/smp.c b/kernel/smp.c
index f43ede0..ad0b68a 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -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);

\
 
 \ /
  Last update: 2021-10-09 12:10    [W:2.566 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site