Commit e1dda8a7 authored Oct 07, 2013 by Rik van Riel Committed by Ingo Molnar Oct 09, 2013

sched/numa: Fix placement of workloads spread across multiple nodes



The load balancer will spread workloads across multiple NUMA nodes,
in order to balance the load on the system. This means that sometimes
a task's preferred node has available capacity, but moving the task
there will not succeed, because that would create too large an imbalance.

In that case, other NUMA nodes need to be considered.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-42-git-send-email-mgorman@suse.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 2c8a50aa

kernel/sched/fair.c

+5 −6

Original line number	Diff line number	Diff line
		@@ -1104,13 +1104,12 @@ static int task_numa_migrate(struct task_struct *p)
		imp = task_faults(env.p, env.dst_nid) - faults;
		update_numa_stats(&env.dst_stats, env.dst_nid);

		/*
		* If the preferred nid has capacity then use it. Otherwise find an
		* alternative node with relatively better statistics.
		*/
		if (env.dst_stats.has_capacity) {
		/* If the preferred nid has capacity, try to use it. */
		if (env.dst_stats.has_capacity)
		task_numa_find_cpu(&env, imp);
		} else {

		/* No space available on the preferred nid. Look elsewhere. */
		if (env.best_cpu == -1) {
		for_each_online_node(nid) {
		if (nid == env.src_nid \|\| nid == p->numa_preferred_nid)
		continue;