linux-kernel - [PATCH] clocksource: really use a margin of 12.5% to limit deferment

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Date:	Thu,  2 Dec 2010 17:08:46 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] clocksource: really use a margin of 12.5% to limit deferment

< ukleinek> tglx: the last comment in clocksource_max_deferment is wrong I
            think.  Unless I'm mistaken the margin is only 2^-5, not 2^-3
< ukleinek> i.e. 3.125%, not 12.5%
...
< tglx> crap, the 3.125% is a bit narrow

So fix the code to really do what the comment specifies.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 kernel/time/clocksource.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index c18d7ef..0ddf372 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -528,7 +528,7 @@ static u64 clocksource_max_deferment(struct clocksource *cs)
 	 * note a margin of 12.5% is used because this can be computed with
 	 * a shift, versus say 10% which would require division.
 	 */
-	return max_nsecs - (max_nsecs >> 5);
+	return max_nsecs - (max_nsecs >> 3);
 }
 
 #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
-- 
1.7.2.3

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