Messages in this thread |  | | From | Vincent Guittot <> | Date | Thu, 9 Oct 2014 16:18:02 +0200 | Subject | Re: [PATCH v7 6/7] sched: replace capacity_factor by usage |
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On 9 October 2014 14:16, Peter Zijlstra <peterz@infradead.org> wrote: > On Tue, Oct 07, 2014 at 02:13:36PM +0200, Vincent Guittot wrote: >> +static inline bool >> +group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) >> { >> + if ((sgs->group_capacity * 100) > >> + (sgs->group_usage * env->sd->imbalance_pct)) >> + return true; > > Why the imb_pct there? We're looking for 100% utilization, not 130 or > whatnot, right?
Having exactly 100% is quite difficult because of various rounding. So i have added a margin/threshold to prevent any excessive change of the state. I have just to use the same margin/threshold than in other place in load balance.
so the current threshold depends of the sched_level. it's around 14% at MC level
> >> + if (sgs->sum_nr_running < sgs->group_weight) >> + return true; > > With the code as it stands, this is the cheaper test (no mults) so why > is it second? > >> + return false; >> +} >> >> +static inline bool >> +group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) >> +{ >> + if (sgs->sum_nr_running <= sgs->group_weight) >> + return false; >> + >> + if ((sgs->group_capacity * 100) < >> + (sgs->group_usage * env->sd->imbalance_pct)) >> + return true; >> >> + return false; >> } > > Same thing here wrt imb_pct
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