Messages in this thread | | | Subject | Re: [sched/rt] Optimization of function pull_rt_task() | From | Steven Rostedt <> | Date | Mon, 16 Apr 2012 12:06:19 -0400 |
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On Sun, 2012-04-15 at 23:45 +0400, Kirill Tkhai wrote: > The condition (src_rq->rt.rt_nr_running) is weak because it doesn't > consider the cases when src_rq has only processes bound to it (when > single cpu is allowed). It may be running kernel thread like > migration/x etc. > > So it's better to use more stronger condition which is able to exclude > above conditions. The function has_pushable_tasks() complitely does > this. A task may be pullable for another cpu rq only if he is pushable > for his own queue.
I considered this before, and for some reason I never did the change. I'll have to think about it. It seems like this would be the obvious case, but I think there was something not so obvious that caused issues. But I don't remember what it was.
I'll have to rethink this again.
Thanks,
-- Steve
> > Signed-off-by: Kirill Tkhai <tkhai@yandex.ru> > --- > kernel/sched/rt.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index c5565c3..61e3086 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -1729,7 +1729,7 @@ static int pull_rt_task(struct rq *this_rq) > /* > * Are there still pullable RT tasks? > */ > - if (src_rq->rt.rt_nr_running <= 1) > + if (!has_pushable_tasks(src_rq)) > goto skip; > > p = pick_next_highest_task_rt(src_rq, this_cpu); >
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