[patch 26/29] softlockup: use cpu_clock() instead of sched_clock()

Greg Kroah-Hartman
2007-11-20T18:38:01Z

[-- Attachment #1: softlockup-use-cpu_clock-instead-of-sched_clock.patch --]
[-- Type: text/plain, Size: 1462 bytes --]

2.6.23-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Ingo Molnar <mingo@elte.hu>

patch a3b13c23f186ecb57204580cc1f2dbe9c284953a in mainline.

sched_clock() is not a reliable time-source, use cpu_clock() instead.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/softlockup.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -43,14 +43,16 @@ static struct notifier_block panic_block
* resolution, and we don't need to waste time with a big divide when
* 2^30ns == 1.074s.
*/
-static unsigned long get_timestamp(void)
+static unsigned long get_timestamp(int this_cpu)
{
- return sched_clock() >> 30; /* 2^30 ~= 10^9 */
+ return cpu_clock(this_cpu) >> 30; /* 2^30 ~= 10^9 */
}

void touch_softlockup_watchdog(void)
{
- __raw_get_cpu_var(touch_timestamp) = get_timestamp();
+ int this_cpu = raw_smp_processor_id();
+
+ __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
}
EXPORT_SYMBOL(touch_softlockup_watchdog);

@@ -96,7 +98,7 @@ void softlockup_tick(void)
return;
}

- now = get_timestamp();
+ now = get_timestamp(this_cpu);

/* Wake up the high-prio watchdog task every second: */
if (now > (touch_timestamp + 1))

--