On Wed, Sep 11, 2013 at 11:11:03AM +0800, Hillf Danton wrote:
> On Tue, Sep 10, 2013 at 5:31 PM, Mel Gorman <mgorman@xxxxxxx> wrote:
> > @@ -5045,15 +5038,50 @@ static int need_active_balance(struct lb_env *env)
> >
> > static int active_load_balance_cpu_stop(void *data);
> >
> > +static int should_we_balance(struct lb_env *env)
> > +{
> > + struct sched_group *sg = env->sd->groups;
> > + struct cpumask *sg_cpus, *sg_mask;
> > + int cpu, balance_cpu = -1;
> > +
> > + /*
> > + * In the newly idle case, we will allow all the cpu's
> > + * to do the newly idle load balance.
> > + */
> > + if (env->idle == CPU_NEWLY_IDLE)
> > + return 1;
> > +
> > + sg_cpus = sched_group_cpus(sg);
> > + sg_mask = sched_group_mask(sg);
> > + /* Try to find first idle cpu */
> > + for_each_cpu_and(cpu, sg_cpus, env->cpus) {
> > + if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu))
> > + continue;
> > +
> > + balance_cpu = cpu;
> > + break;
> > + }
> > +
> > + if (balance_cpu == -1)
> > + balance_cpu = group_balance_cpu(sg);
> > +
> > + /*
> > + * First idle cpu or the first cpu(busiest) in this sched group
> > + * is eligible for doing load balancing at this and above domains.
> > + */
> > + return balance_cpu != env->dst_cpu;
>
> FYI: Here is a bug reported by Dave Chinner.
> https://lkml.org/lkml/2013/9/10/1
>
> And lets see if any changes in your SpecJBB results without it.
>
Thanks for pointing that out. I've picked up the one-liner fix.
--
Mel Gorman
SUSE Labs
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