Messages in this thread Patch in this message | | | Subject | Re: [RFC 4/4] sched/fair: Take into runnable_avg to classify group | From | Valentin Schneider <> | Date | Thu, 13 Feb 2020 18:32:46 +0000 |
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On 2/11/20 5:46 PM, Vincent Guittot wrote: > Take into account the new runnable_avg signal to classify a group and to > mitigate the volatility of util_avg in face of intensive migration. > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > kernel/sched/fair.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 7d7cb207be30..5f8f12c902d4 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7691,6 +7691,7 @@ struct sg_lb_stats { > unsigned long group_load; /* Total load over the CPUs of the group */ > unsigned long group_capacity; > unsigned long group_util; /* Total utilization of the group */ > + unsigned long group_runnable; /* Total utilization of the group */ ^^^^^^^^^^^ "Total runnable" hurts my eyes, but in any case this shouldn't be just "utilization".
> unsigned int sum_nr_running; /* Nr of tasks running in the group */ > unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */ > unsigned int idle_cpus; > @@ -7911,6 +7912,10 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs) > if (sgs->sum_nr_running < sgs->group_weight) > return true; > > + if ((sgs->group_capacity * imbalance_pct) < > + (sgs->group_runnable * 100)) > + return false; > +
I haven't stared long enough at patch 2, but I'll ask anyway - with this new condition, do we still need the next one (based on util)? AIUI group_runnable is >= group_util, so if group_runnable is within the allowed margin then group_util has to be as well.
> if ((sgs->group_capacity * 100) > > (sgs->group_util * imbalance_pct)) > return true; > @@ -7936,6 +7941,10 @@ group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs) > (sgs->group_util * imbalance_pct)) > return true; > > + if ((sgs->group_capacity * imbalance_pct) < > + (sgs->group_runnable * 100)) > + return true; > +
Ditto on the group_runnable >= group_util - we could get rid of the check above this one.
> return false; > } > > @@ -8030,6 +8039,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, > > sgs->group_load += cpu_load(rq); > sgs->group_util += cpu_util(i); > + sgs->group_runnable += cpu_runnable(rq); > sgs->sum_h_nr_running += rq->cfs.h_nr_running; > > nr_running = rq->nr_running; >
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