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 ?
> Some of runtime and deadline run with millisecond level by
> reading kernershark.
> The problem is caused by a conditional judgment "delta > 10000".
> Because no hrtimer start up to control the runtime when runtime is less than
> 10us.
> So the process will continue to run until tick-period coming.
> For fixing this problem, Let delta is equal to 10us when it is less than 10us.
> So the hrtimer will start up to control the end of process.
>
> Signed-off-by: xiaofeng.yan <xiaofeng....@huawei.com>
Always when sending patches for deadline, also CC Juri.
> ---
> kernel/sched/deadline.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index fc4f98b1..dfefa82 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -997,10 +997,8 @@ static void check_preempt_curr_dl(struct rq *rq, struct
> task_struct *p,
> #ifdef CONFIG_SCHED_HRTICK
> static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
> {
> - s64 delta = p->dl.dl_runtime - p->dl.runtime;
> -
> - if (delta > 10000)
> - hrtick_start(rq, p->dl.runtime);
> + s64 delta = p->dl.runtime > 10000 ? p->dl.runtime : 10000;
> + hrtick_start(rq, delta);
Yeah, that looks funny. And seeing how the only other user does
something similar:
hrtick_start_fair()
delta = max(10000ULL, delta)
hrtick_start(rq, delta)
Does it make sense to move this max() into hrtick_start()?
Also; and I don't think you mentioned that but did fix, the argument to
hrtick_start() is wrong, it should be the delta, not the absolute
timeout.
pgpV7gidRiP8O.pgp
Description: PGP signature
