linux-kernel - [PATCH 01/10] nohz: Remove idle task special case

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Date:	Thu, 23 Jul 2015 18:42:06 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Ingo Molnar <mingo@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Rik van Riel <riel@...hat.com>
Subject: [PATCH 01/10] nohz: Remove idle task special case

On nohz full early days, idle dynticks and full dynticks weren't well
integrated and we couldn't risk full dynticks calls on idle without
risking messing up tick idle statistics. This is why we prevented such
thing to happen.

Nowadays full dynticks and idle dynticks are better integrated and
interact without known issue.

So lets remove that.

Reviewed-by: Rik van Riel <riel@...hat.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/time/tick-sched.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index c792429..d6c8eff 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -208,10 +208,8 @@ void __tick_nohz_full_check(void)
 	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
 
 	if (tick_nohz_full_cpu(smp_processor_id())) {
-		if (ts->tick_stopped && !is_idle_task(current)) {
-			if (!can_stop_full_tick())
-				tick_nohz_restart_sched_tick(ts, ktime_get());
-		}
+		if (ts->tick_stopped && !can_stop_full_tick())
+			tick_nohz_restart_sched_tick(ts, ktime_get());
 	}
 }
 
@@ -710,7 +708,7 @@ static void tick_nohz_full_stop_tick(struct tick_sched *ts)
 #ifdef CONFIG_NO_HZ_FULL
 	int cpu = smp_processor_id();
 
-	if (!tick_nohz_full_cpu(cpu) || is_idle_task(current))
+	if (!tick_nohz_full_cpu(cpu))
 		return;
 
 	if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE)
-- 
2.1.4

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