Messages in this thread | | | Date | Wed, 6 Sep 2017 12:44:20 +0200 | From | Peter Zijlstra <> | Subject | Re: Abysmal scheduler performance in Linus' tree? |
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On Wed, Sep 06, 2017 at 11:18:46AM +0100, Chris Wilson wrote:
> > +static void get_llc_stats(struct llc_stats *stats, int cpu) > > +{ > > + struct sched_domain_shared *sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); > > + > > + if (!sds) { > > + memset(&stats, 0, sizeof(*stats)); > > Yes, I even sent you a mail about it ;)
Bah, too much email, sorry :-(
> > + /* > > + * The has_capacity stuff is not SMT aware, but by trying to balance > > + * the nr_running on both ends we try and fill the domain at equal > > + * rates, thereby first consuming cores before siblings. > > + */ > > + > > + /* if the old cache has capacity, stay there */ > > + if (prev_stats.has_capacity && prev_stats.nr_running < this_stats.nr_running+1) > > + return false; > > + > > + /* if this cache has capacity, come here */ > > + if (this_stats.has_capacity && this_stats.nr_running < prev_stats.nr_running+1) > > + return true; > > This is still not working as intended, it should be > > if (this_stats.has_capacity && this_stats.nr_running+1 < prev_stats.nr_running) > return true; > > to fix the regression.
Argh, you're quite right. Let me do a patch for that.
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