On Fri, Sep 16, 2016 at 06:28:51PM -0700, Joonwoo Park wrote:
> From: Srivatsa Vaddagiri <va...@codeaurora.org>
>
> SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot
Right, but I always found the overhead of the thing too high to be
really useful.
How come you're using this?
> joonwoop: Do we also need to update or remove if-statement inside
> hrtick_update()?
> I guess not because hrtick_update() doesn't want to start hrtick when cfs_rq
> has large number of nr_running where slice is longer than sched_latency.
Right, you want that to match with whatever sched_slice() does.
> +++ b/kernel/sched/fair.c
> @@ -4458,7 +4458,7 @@ static void hrtick_start_fair(struct rq *rq, struct
> task_struct *p)
>
> WARN_ON(task_rq(p) != rq);
>
> - if (cfs_rq->nr_running > 1) {
> + if (rq->cfs.h_nr_running > 1) {
> u64 slice = sched_slice(cfs_rq, se);
> u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
> s64 delta = slice - ran;
Yeah, that looks right. I don't think I've ever tried hrtick with
cgroups enabled...
