Re: [patch v3 5/6] sched, ttwu_queue: queue remote wakeups onlywhen crossing cache domains

From: Peter Zijlstra
Date: Thu Dec 08 2011 - 04:29:52 EST


On Wed, 2011-12-07 at 11:20 -0800, Suresh Siddha wrote:

> > +DEFINE_PER_CPU(int, sd_top_spr_id);
>
> pkg_srid (shared resource id)?

How about sd_llc{,_id} ?

> > +
> > +static void update_top_cache_domain(int cpu)
> > +{
> > + struct sched_domain *sd;
> > + int id = -1;
> > +
> > + sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
> > + if (sd)
> > + id = cpumask_first(sched_domain_span(sd));
>
> if there is no sd with shared pkg resources, then id has to be set to
> 'cpu'.

Ah, right. I hadn't considered the case where the LLC isn't shared at
all.

> > + rcu_assign_pointer(per_cpu(sd_top_spr, cpu), sd);
> > + per_cpu(sd_top_spr_id, cpu) = id;
>
> Otherwise it looks good.

Thanks!
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