Re: [PATCH] sched/rt: overrun could happen in start_hrtick_dl

From: xiaofeng.yan
Date: Mon Jul 07 2014 - 22:51:22 EST


On 2014/7/8 10:40, Li Zefan wrote:
On 2014/7/8 9:10, xiaofeng.yan wrote:
On 2014/7/7 16:41, Peter Zijlstra wrote:
On Fri, Jul 04, 2014 at 12:02:21PM +0000, xiaofeng.yan wrote:
It could be wrong for the precision of runtime and deadline
when the precision is within microsecond level. For example:
Task runtime deadline period
P1 200us 500us 500us

This case need enbale HRTICK feature by the next command
PC#echo "HRTICK" > /sys/kernel/debug/sched_features
PC#./schedtool -E -t 200000:500000 -e ./test&
PC#trace-cmd record -e sched_switch
Are you actually using HRTICK ?
yes, If HRTICK is close , then all of runtime and deadline will be wrong.
I think what peter meant is, do you use HRTICK in products or
just use it for testing/experiment?

Thanks for your timely comments. In fact, We use HRTICK feature in product. We need microsecond level
precision.

Thanks
Yan
.



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