From: David S. Miller <davem@davemloft.net>
Date: Sun, 24 Sep 2006 01:31:42 +0000 (-0700)
Subject: [SPARC64]: Fix sched_clock() wrapping every ~17 seconds.
X-Git-Tag: v2.6.19-rc1~1268
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=e17ba8f51f69782abc4575dd30848ba5eafaa797;p=linux-2.6-omap-h63xx.git

[SPARC64]: Fix sched_clock() wrapping every ~17 seconds.

Unfortunately, sparc64 doesn't have an easy way to do a "64 X 64 -->
128" bit multiply like PowerPC and IA64 do.  We were doing a
"64 X 64 --> 64" bit multiple which causes overflow very quickly with
a 30-bit quotient shift.

So use a quotientshift count of 10 instead of 30, just like x86 and
ARM do.

This also fixes the wrapping of printk timestamp values every ~17
seconds.

Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/arch/sparc64/kernel/time.c b/arch/sparc64/kernel/time.c
index 094d3e35be1..b0b4feeec09 100644
--- a/arch/sparc64/kernel/time.c
+++ b/arch/sparc64/kernel/time.c
@@ -983,7 +983,7 @@ static struct time_interpolator sparc64_cpu_interpolator = {
 };
 
 /* The quotient formula is taken from the IA64 port. */
-#define SPARC64_NSEC_PER_CYC_SHIFT	30UL
+#define SPARC64_NSEC_PER_CYC_SHIFT	10UL
 void __init time_init(void)
 {
 	unsigned long clock = sparc64_init_timers();