linux-kernel - [PATCH 3.12 040/116] sched: Clean up idle task SMP logic

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Message-Id: <ee36ee687fa390924b88ce40bf1789a8abb340bd.1457082108.git.jslaby@suse.cz>
Date:	Fri,  4 Mar 2016 10:01:25 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	alex.shi@...aro.org, mingo@...nel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Byungchul Park <byungchul.park@....com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 040/116] sched: Clean up idle task SMP logic

From: Peter Zijlstra <peterz@...radead.org>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 6c3b4d44ba2838f00614a5a2d777d4401e0bfd71 upstream.

The idle post_schedule flag is just a vile waste of time, furthermore
it appears unneeded, move the idle_enter_fair() call into
pick_next_task_idle().

Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: alex.shi@...aro.org
Cc: mingo@...nel.org
Cc: Steven Rostedt <rostedt@...dmis.org>
Link: http://lkml.kernel.org/n/tip-aljykihtxJt3mkokxi0qZurb@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Byungchul Park <byungchul.park@....com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 kernel/sched/idle_task.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
index d8da01008d39..ecc371e86da1 100644
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -19,11 +19,6 @@ static void pre_schedule_idle(struct rq *rq, struct task_struct *prev)
 	idle_exit_fair(rq);
 	rq_last_tick_reset(rq);
 }
-
-static void post_schedule_idle(struct rq *rq)
-{
-	idle_enter_fair(rq);
-}
 #endif /* CONFIG_SMP */
 /*
  * Idle tasks are unconditionally rescheduled:
@@ -37,8 +32,7 @@ static struct task_struct *pick_next_task_idle(struct rq *rq)
 {
 	schedstat_inc(rq, sched_goidle);
 #ifdef CONFIG_SMP
-	/* Trigger the post schedule to do an idle_enter for CFS */
-	rq->post_schedule = 1;
+	idle_enter_fair(rq);
 #endif
 	return rq->idle;
 }
@@ -102,7 +96,6 @@ const struct sched_class idle_sched_class = {
 #ifdef CONFIG_SMP
 	.select_task_rq		= select_task_rq_idle,
 	.pre_schedule		= pre_schedule_idle,
-	.post_schedule		= post_schedule_idle,
 #endif
 
 	.set_curr_task          = set_curr_task_idle,
-- 
2.7.2