Messages in this thread |  | | | Date | Thu, 12 Mar 2009 14:33:28 -0700 | | From | Darren Hart <> | | Subject | Re: [tip:core/futexes] futex: use current->time_slack_ns for rt tasks too |
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Arjan van de Ven wrote: > Peter Zijlstra wrote: >>>> --- >>>> >>>> Subject: sched: adjust timer_slack_ns on scheduler policy change >>>> From: Peter Zijlstra <a.p.zijlstra@chello.nl> >>>> Date: Thu Mar 12 15:01:02 CET 2009 >>>> >>>> Ensure RT tasks have 0 timer slack. >>>> >>>> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> >>>> --- >>>> kernel/sched.c | 2 ++ >>>> 1 file changed, 2 insertions(+) >>>> >>>> Index: linux-2.6/kernel/sched.c >>>> =================================================================== >>>> --- linux-2.6.orig/kernel/sched.c >>>> +++ linux-2.6/kernel/sched.c >>>> @@ -5511,10 +5511,12 @@ __setscheduler(struct rq *rq, struct tas >>>> case SCHED_NORMAL: >>>> case SCHED_BATCH: >>>> case SCHED_IDLE: >>>> + p->timer_slack_ns = p->default_timer_slack_ns; >>>> p->sched_class = &fair_sched_class; >>>> break; >>>> case SCHED_FIFO: >>>> case SCHED_RR: >>>> + p->timer_slack_ns = 0; >>>> p->sched_class = &rt_sched_class; >>>> break; >>>> } >>>> >> >> Looking at the default_timer_slack_ns stuff, do we want something like >> the below? > > the original idea was that you had a default slack that you got from > exec time, > and then something you could just tweak around yourself independently.... > > this would throw that out of the window.
It seems to me that changing your scheduling class from userspace would be reasonable justification to change the timer slack to a default value for that class. Thoughts?
-- Darren Hart IBM Linux Technology Center Real-Time Linux Team
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