Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b1ad065e authored by Rik van Riel's avatar Rik van Riel Committed by Ingo Molnar
Browse files

sched/numa: Update migrate_improves/degrades_locality() 



Update the migrate_improves/degrades_locality() functions with
knowledge of pseudo-interleaving.

Do not consider moving tasks around within the set of group's active
nodes as improving or degrading locality. Instead, leave the load
balancer free to balance the load between a numa_group's active nodes.

Also, switch from the group/task_weight functions to the group/task_fault
functions. The "weight" functions involve a division, but both calls use
the same divisor, so there's no point in doing that from these functions.

On a 4 node (x10 core) system, performance of SPECjbb2005 seems
unaffected, though the number of migrations with 2 8-warehouse wide
instances seems to have almost halved, due to the scheduler running
each instance on a single node.

Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Link: http://lkml.kernel.org/r/20140515130306.61aae7db@cuia.bos.redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e63da036

kernel/sched/fair.c

+29 −13
Original line number Diff line number Diff line
@@ -5123,6 +5123,7 @@ task_hot(struct task_struct *p, u64 now) 
/* Returns true if the destination node has incurred more faults */

static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)

{

	struct numa_group *numa_group = rcu_dereference(p->numa_group);

	int src_nid, dst_nid;



	if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults_memory ||
@@ -5136,21 +5137,29 @@ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) 
	if (src_nid == dst_nid)

		return false;



	/* Always encourage migration to the preferred node. */

	if (dst_nid == p->numa_preferred_nid)

	if (numa_group) {

		/* Task is already in the group's interleave set. */

		if (node_isset(src_nid, numa_group->active_nodes))

			return false;



		/* Task is moving into the group's interleave set. */

		if (node_isset(dst_nid, numa_group->active_nodes))

			return true;



	/* If both task and group weight improve, this move is a winner. */

	if (task_weight(p, dst_nid) > task_weight(p, src_nid) &&

	    group_weight(p, dst_nid) > group_weight(p, src_nid))

		return group_faults(p, dst_nid) > group_faults(p, src_nid);

	}



	/* Encourage migration to the preferred node. */

	if (dst_nid == p->numa_preferred_nid)

		return true;



	return false;

	return task_faults(p, dst_nid) > task_faults(p, src_nid);

}





static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)

{

	struct numa_group *numa_group = rcu_dereference(p->numa_group);

	int src_nid, dst_nid;



	if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
@@ -5165,16 +5174,23 @@ static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) 
	if (src_nid == dst_nid)

		return false;



	/* Migrating away from the preferred node is always bad. */

	if (src_nid == p->numa_preferred_nid)

	if (numa_group) {

		/* Task is moving within/into the group's interleave set. */

		if (node_isset(dst_nid, numa_group->active_nodes))

			return false;



		/* Task is moving out of the group's interleave set. */

		if (node_isset(src_nid, numa_group->active_nodes))

			return true;



	/* If either task or group weight get worse, don't do it. */

	if (task_weight(p, dst_nid) < task_weight(p, src_nid) ||

	    group_weight(p, dst_nid) < group_weight(p, src_nid))

		return group_faults(p, dst_nid) < group_faults(p, src_nid);

	}



	/* Migrating away from the preferred node is always bad. */

	if (src_nid == p->numa_preferred_nid)

		return true;



	return false;

	return task_faults(p, dst_nid) < task_faults(p, src_nid);

}



#else