Messages in this thread | | | Date | Thu, 11 Sep 2014 12:13:08 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v5 08/12] sched: move cfs task on a CPU with higher capacity |
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On Tue, Aug 26, 2014 at 01:06:51PM +0200, Vincent Guittot wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 18db43e..60ae1ce 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6049,6 +6049,14 @@ static bool update_sd_pick_busiest(struct lb_env *env, > return true; > } > > + /* > + * The group capacity is reduced probably because of activity from other > + * sched class or interrupts which use part of the available capacity > + */ > + if ((sg->sgc->capacity_orig * 100) > (sgs->group_capacity * > + env->sd->imbalance_pct)) > + return true; > + > return false; > } > > @@ -6534,13 +6542,23 @@ static int need_active_balance(struct lb_env *env) > struct sched_domain *sd = env->sd; > > if (env->idle == CPU_NEWLY_IDLE) { > + int src_cpu = env->src_cpu; > > /* > * ASYM_PACKING needs to force migrate tasks from busy but > * higher numbered CPUs in order to pack all tasks in the > * lowest numbered CPUs. > */ > - if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) > + if ((sd->flags & SD_ASYM_PACKING) && src_cpu > env->dst_cpu) > + return 1; > + > + /* > + * If the CPUs share their cache and the src_cpu's capacity is > + * reduced because of other sched_class or IRQs, we trig an > + * active balance to move the task > + */ > + if ((capacity_orig_of(src_cpu) * 100) > (capacity_of(src_cpu) * > + sd->imbalance_pct)) > return 1; > }
Should you not also check -- in both cases -- that the destination is any better?
Also, there's some obvious repetition going on there, maybe add a helper?
Also, both sites should probably ensure they're operating in the non-saturated/overloaded scenario. Because as soon as we're completely saturated we want SMP nice etc. and that all already works right (presumably).
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