linux-kernel - [PATCH 3/3] nohz: Include local CPU in full dynticks global kick

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Date:	Fri,  2 Aug 2013 18:29:56 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>, Jiri Olsa <jolsa@...hat.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Li Zhong <zhong@...ux.vnet.ibm.com>,
	Mike Galbraith <efault@....de>,
	Kevin Hilman <khilman@...aro.org>
Subject: [PATCH 3/3] nohz: Include local CPU in full dynticks global kick

tick_nohz_full_kick_all() is useful to notify all full dynticks
CPUs that there is a system state change to checkout before
re-evaluating the need for the tick.

Unfortunately this is implemented using smp_call_function_many()
that ignores the local CPU. This CPU also needs to re-evaluate
the tick.

on_each_cpu_mask() is not useful either because we don't want to
re-evaluate the tick state in place but asynchronously from an IPI
to avoid messing up with any random locking scenario.

Sol lets call tick_nohz_full_kick() from tick_nohz_full_kick_all()
so that the usual irq work takes care of it.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Li Zhong <zhong@...ux.vnet.ibm.com>
Cc: Mike Galbraith <efault@....de>
Cc: Kevin Hilman <khilman@...aro.org>
---
 kernel/time/tick-sched.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e80183f..30849d4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -244,6 +244,7 @@ void tick_nohz_full_kick_all(void)
 	preempt_disable();
 	smp_call_function_many(nohz_full_mask,
 			       nohz_full_kick_ipi, NULL, false);
+	tick_nohz_full_kick();
 	preempt_enable();
 }
 
-- 
1.7.5.4

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