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Message-Id: <1390282399-17091-1-git-send-email-alex.shi@linaro.org>
Date: Tue, 21 Jan 2014 13:33:18 +0800
From: Alex Shi <alex.shi@...aro.org>
To: mingo@...hat.com, peterz@...radead.org, morten.rasmussen@....com,
vincent.guittot@...aro.org, daniel.lezcano@...aro.org,
efault@....de
Cc: wangyun@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
Alex Shi <alex.shi@...aro.org>
Subject: [RFC PATCH 1/2] sched/update_avg: avoid negative time
rq->avg_idle try to reflect the average idle time between the cpu idle
and first wakeup. But in the function, it maybe get a negative value
if old avg_idle is too small. Then this negative value will be double
counted in next time calculation. Guess that is not the original purpose,
so recalibrate it to zero.
Signed-off-by: Alex Shi <alex.shi@...aro.org>
---
kernel/sched/core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 30eb011..af9121c6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1358,6 +1358,9 @@ static void update_avg(u64 *avg, u64 sample)
{
s64 diff = sample - *avg;
*avg += diff >> 3;
+
+ if (*avg < 0)
+ *avg = 0;
}
#endif
--
1.8.1.2
--
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