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authorRik van Riel <riel@redhat.com>2013-10-07 11:29:19 +0100
committerIngo Molnar <mingo@kernel.org>2013-10-09 14:47:43 +0200
commite1dda8a797b59d7ec4b17e393152ec3273a552d5 (patch)
tree256769c0da413cb1d5fcaeabd06316d24804259c /kernel/sched
parent2c8a50aa873a7e1d6cc0913362051ff9912dc6ca (diff)
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>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 09aac90df89e..aa561c8dc899 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -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;