linux-kernel - [PATCH 25/38] tick-sched: don't call local_softirq_pending() thrice in can_stop_idle

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Date:	Mon, 14 Apr 2014 21:53:47 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	tglx@...utronix.de
Cc:	linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
	fweisbec@...il.com, Arvind.Chauhan@....com,
	linaro-networking@...aro.org,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH 25/38] tick-sched: don't call local_softirq_pending() thrice in can_stop_idle_tick()

can_stop_idle_tick() checks if a local softirq is pending or not, and in case
it is pending we call the same routine two more times.

Rather store the value in a local variable and reuse it.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 kernel/time/tick-sched.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 5a99859..b7b09b9 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -691,6 +691,8 @@ static void tick_nohz_full_stop_tick(struct tick_sched *ts)
 
 static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
 {
+	unsigned int softirq;
+
 	/*
 	 * If this cpu is offline and it is the one which updates
 	 * jiffies, then give up the assignment and let it be taken by
@@ -712,13 +714,11 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
 	if (need_resched())
 		return false;
 
-	if (unlikely(local_softirq_pending())) {
+	if (unlikely((softirq = local_softirq_pending()))) {
 		static int ratelimit;
 
-		if (ratelimit < 10 &&
-		    (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
-			pr_warn("NOHZ: local_softirq_pending %02x\n",
-				(unsigned int) local_softirq_pending());
+		if (ratelimit < 10 && (softirq & SOFTIRQ_STOP_IDLE_MASK)) {
+			pr_warn("NOHZ: local_softirq_pending %02x\n", softirq);
 			ratelimit++;
 		}
 		return false;
-- 
1.7.12.rc2.18.g61b472e

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