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Subject[tip:perf/urgent] watchdog: Fix rounding bug in get_sample_period()
Commit-ID:  824c6b7f6294101f30e141117def224a56c203e6
Gitweb: http://git.kernel.org/tip/824c6b7f6294101f30e141117def224a56c203e6
Author: Mandeep Singh Baines <msb@chromium.org>
AuthorDate: Sun, 22 May 2011 22:10:20 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 23 May 2011 11:58:58 +0200

watchdog: Fix rounding bug in get_sample_period()

In get_sample_period(), softlockup_thresh is integer divided by
5 before the multiplication by NSEC_PER_SEC. This results in
softlockup_thresh being rounded down to the nearest integer
multiple of 5.

For example, a softlockup_thresh of 4 rounds down to 0.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1306127423-3347-1-git-send-email-msb@chromium.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/watchdog.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 14733d4..a06972d 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -110,7 +110,7 @@ static unsigned long get_sample_period(void)
* increment before the hardlockup detector generates
* a warning
*/
- return softlockup_thresh / 5 * NSEC_PER_SEC;
+ return softlockup_thresh * (NSEC_PER_SEC / 5);
}

/* Commands for resetting the watchdog */

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