linux-kernel - [PATCH -rt] cycles_to

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Date:	Wed, 12 Dec 2007 12:12:58 -0800
From:	Daniel Walker <dwalker@...sta.com>
To:	rostedt@...dmis.org
Cc:	mingo@...e.hu, linux-kernel@...r.kernel.org,
	linux-rt-users@...r.kernel.org, johnstul@...ibm.com
Subject: [PATCH -rt] cycles_to_usecs rounding fix

do_div() rounds down, so we add have the divisor to round up. This effected my
change to preempt_max_latency. Each time you read preempt_max_latency it gets 
rounded lower.

Signed-off-by: Daniel Walker <dwalker@...sta.com>


---
 kernel/time/timekeeping.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6.23/kernel/time/timekeeping.c
===================================================================
--- linux-2.6.23.orig/kernel/time/timekeeping.c
+++ linux-2.6.23/kernel/time/timekeeping.c
@@ -144,7 +144,8 @@ unsigned long notrace cycles_to_usecs(cy
 {
 	u64 ret = cyc2ns(clock, cycles);
 
-	do_div(ret, 1000);
+	ret += NSEC_PER_USEC/2; /* For rounding in do_div() */
+	do_div(ret, NSEC_PER_USEC);
 
 	return ret;
 }
-- 

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