Messages in this thread | | | Date | Mon, 13 Jul 2015 18:25:35 +0900 | From | Byungchul Park <> | Subject | Re: [PATCH v2] sched: let __sched_period() use rq's nr_running |
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On Mon, Jul 13, 2015 at 10:26:09AM +0200, Peter Zijlstra wrote: > On Fri, Jul 10, 2015 at 05:11:30PM +0900, byungchul.park@lge.com wrote: > > From: Byungchul Park <byungchul.park@lge.com> > > > > __sched_period() returns a period which a rq can have. the period has to be > > stretched by the number of task *the rq has*, when nr_running > nr_latency. > > otherwise, task slice can be very smaller than sysctl_sched_min_granularity > > depending on the position of tg hierarchy when CONFIG_FAIR_GROUP_SCHED. > > > > Signed-off-by: Byungchul Park <byungchul.park@lge.com> > > --- > > kernel/sched/fair.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 09456fc..8ae7aeb 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -635,7 +635,7 @@ static u64 __sched_period(unsigned long nr_running) > > */ > > static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) > > { > > - u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); > > + u64 slice = __sched_period(rq_of(cfs_rq)->nr_running + !se->on_rq); > > > > for_each_sched_entity(se) { > > struct load_weight *load; > > This really doesn't make sense; look at what that > for_each_sched_entity() loop does below this.
hello,
for_each_sched_entity() loop is distributing slice to se with consideration for both hierarchy and its weight, walking from the passed se to the top rq.
i am just talking about how to get a whole period value. my question is "why does it use local cfs's nr_running to get a whole period value?".
> > I agree that sched_slice() is a difficult proposition in the face of > cgroup, but everything is, cgroups suck arse, they make everything hard.
i don't make an issue of the way for cgroups to work though it already have many problems as you said.
thank you for commenting, byungchul
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