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Commit 7bd95320 authored by Rik van Riel's avatar Rik van Riel Committed by Ingo Molnar
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sched/numa: Prepare for complex topology placement 



Preparatory patch for adding NUMA placement on systems with
complex NUMA topology. Also fix a potential divide by zero
in group_weight()

Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Tested-by: default avatarChegu Vinod <chegu_vinod@hp.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413530994-9732-4-git-send-email-riel@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e3fe70b1

kernel/sched/fair.c

+37 −20
Original line number Diff line number Diff line
@@ -931,9 +931,10 @@ static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) 
 * larger multiplier, in order to group tasks together that are almost

 * evenly spread out between numa nodes.

 */

static inline unsigned long task_weight(struct task_struct *p, int nid)

static inline unsigned long task_weight(struct task_struct *p, int nid,

					int dist)

{

	unsigned long total_faults;

	unsigned long faults, total_faults;



	if (!p->numa_faults_memory)

		return 0;
@@ -943,15 +944,25 @@ static inline unsigned long task_weight(struct task_struct *p, int nid) 
	if (!total_faults)

		return 0;



	return 1000 * task_faults(p, nid) / total_faults;

	faults = task_faults(p, nid);

	return 1000 * faults / total_faults;

}



static inline unsigned long group_weight(struct task_struct *p, int nid)

static inline unsigned long group_weight(struct task_struct *p, int nid,

					 int dist)

{

	if (!p->numa_group || !p->numa_group->total_faults)

	unsigned long faults, total_faults;



	if (!p->numa_group)

		return 0;



	total_faults = p->numa_group->total_faults;



	if (!total_faults)

		return 0;



	return 1000 * group_faults(p, nid) / p->numa_group->total_faults;

	faults = group_faults(p, nid);

	return 1000 * faults / total_faults;

}



bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
@@ -1084,6 +1095,7 @@ struct task_numa_env { 
	struct numa_stats src_stats, dst_stats;



	int imbalance_pct;

	int dist;



	struct task_struct *best_task;

	long best_imp;
@@ -1163,6 +1175,7 @@ static void task_numa_compare(struct task_numa_env *env, 
	long load;

	long imp = env->p->numa_group ? groupimp : taskimp;

	long moveimp = imp;

	int dist = env->dist;



	rcu_read_lock();
@@ -1196,8 +1209,8 @@ static void task_numa_compare(struct task_numa_env *env, 
		 * in any group then look only at task weights.

		 */

		if (cur->numa_group == env->p->numa_group) {

			imp = taskimp + task_weight(cur, env->src_nid) -

			      task_weight(cur, env->dst_nid);

			imp = taskimp + task_weight(cur, env->src_nid, dist) -

			      task_weight(cur, env->dst_nid, dist);

			/*

			 * Add some hysteresis to prevent swapping the

			 * tasks within a group over tiny differences.
@@ -1211,11 +1224,11 @@ static void task_numa_compare(struct task_numa_env *env, 
			 * instead.

			 */

			if (cur->numa_group)

				imp += group_weight(cur, env->src_nid) -

				       group_weight(cur, env->dst_nid);

				imp += group_weight(cur, env->src_nid, dist) -

				       group_weight(cur, env->dst_nid, dist);

			else

				imp += task_weight(cur, env->src_nid) -

				       task_weight(cur, env->dst_nid);

				imp += task_weight(cur, env->src_nid, dist) -

				       task_weight(cur, env->dst_nid, dist);

		}

	}
@@ -1314,7 +1327,7 @@ static int task_numa_migrate(struct task_struct *p) 
	};

	struct sched_domain *sd;

	unsigned long taskweight, groupweight;

	int nid, ret;

	int nid, ret, dist;

	long taskimp, groupimp;



	/*
@@ -1342,12 +1355,13 @@ static int task_numa_migrate(struct task_struct *p) 
		return -EINVAL;

	}



	taskweight = task_weight(p, env.src_nid);

	groupweight = group_weight(p, env.src_nid);

	update_numa_stats(&env.src_stats, env.src_nid);

	env.dst_nid = p->numa_preferred_nid;

	taskimp = task_weight(p, env.dst_nid) - taskweight;

	groupimp = group_weight(p, env.dst_nid) - groupweight;

	dist = env.dist = node_distance(env.src_nid, env.dst_nid);

	taskweight = task_weight(p, env.src_nid, dist);

	groupweight = group_weight(p, env.src_nid, dist);

	update_numa_stats(&env.src_stats, env.src_nid);

	taskimp = task_weight(p, env.dst_nid, dist) - taskweight;

	groupimp = group_weight(p, env.dst_nid, dist) - groupweight;

	update_numa_stats(&env.dst_stats, env.dst_nid);



	/* Try to find a spot on the preferred nid. */
@@ -1359,12 +1373,15 @@ static int task_numa_migrate(struct task_struct *p) 
			if (nid == env.src_nid || nid == p->numa_preferred_nid)

				continue;



			dist = node_distance(env.src_nid, env.dst_nid);



			/* Only consider nodes where both task and groups benefit */

			taskimp = task_weight(p, nid) - taskweight;

			groupimp = group_weight(p, nid) - groupweight;

			taskimp = task_weight(p, nid, dist) - taskweight;

			groupimp = group_weight(p, nid, dist) - groupweight;

			if (taskimp < 0 && groupimp < 0)

				continue;



			env.dist = dist;

			env.dst_nid = nid;

			update_numa_stats(&env.dst_stats, env.dst_nid);

			task_numa_find_cpu(&env, taskimp, groupimp);