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Date:	Sat, 17 Mar 2012 22:31:35 +0100
From:	Felix Fietkau <nbd@...nwrt.org>
To:	linux-kernel@...r.kernel.org
Cc:	tglx@...utronix.de
Subject: [PATCH] timer: optimize apply_slack()

__fls(mask) is equivalent to find_last_bit(&mask, BITS_PER_LONG), but cheaper.
find_last_bit was showing up high on the list when I was profiling for stalls
on icache misses on a system with very small cache size (MIPS).

Signed-off-by: Felix Fietkau <nbd@...nwrt.org>
---
 kernel/timer.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/timer.c b/kernel/timer.c
index a297ffc..659371e 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -809,7 +809,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
 	if (mask == 0)
 		return expires;
 
-	bit = find_last_bit(&mask, BITS_PER_LONG);
+	bit = __fls(mask);
 
 	mask = (1 << bit) - 1;
 
-- 
1.7.3.2

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