Re: [PATCH 5/8] sched: Favour moving tasks towards the preferred node

From: Peter Zijlstra
Date: Thu Jun 27 2013 - 12:01:41 EST


On Wed, Jun 26, 2013 at 03:38:04PM +0100, Mel Gorman wrote:
> @@ -3897,6 +3907,28 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
> return delta < (s64)sysctl_sched_migration_cost;
> }
>
> +/* Returns true if the destination node has incurred more faults */
> +static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
> +{
> + int src_nid, dst_nid;
> +
> + if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
> + return false;
> +
> + src_nid = cpu_to_node(env->src_cpu);
> + dst_nid = cpu_to_node(env->dst_cpu);
> +
> + if (src_nid == dst_nid)
> + return false;
> +
> + if (p->numa_migrate_seq < sysctl_numa_balancing_settle_count &&
> + p->numa_preferred_nid == dst_nid)
> + return true;
> +
> + return false;
> +}
> +

This references ->numa_faults, which is declared under NUMA_BALANCING
but lacks any such conditionality here.
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