linux-kernel - [PATCH 6/6] sched: Inline the need_resched test into the caller for _cond

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Date:	Fri, 16 Aug 2013 14:17:24 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	linux-kernel@...r.kernel.org
Cc:	x86@...nel.org, peterz@...radead.org, akpm@...ux-foundation.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 6/6] sched: Inline the need_resched test into the caller for _cond_resched

From: Andi Kleen <ak@...ux.intel.com>

_cond_resched does at least two explicit calls just to decide to do
nothing: _cond_resched and should_resched(). Inline a need_resched()
into the caller to avoid these calls in the common case of no reschedule
being needed.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 include/linux/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 97f4b78..dd3fafc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2435,7 +2435,7 @@ extern int __cond_resched_softirq(void);
 
 #ifdef CONFIG_PREEMPT_VOLUNTARY
 extern int _cond_resched(void);
-# define might_resched() _cond_resched()
+# define might_resched() (need_resched() ? _cond_resched() : 0)
 #else
 # define might_resched() do { } while (0)
 #endif
-- 
1.8.3.1

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