From e1dda8a797b59d7ec4b17e393152ec3273a552d5 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Mon, 7 Oct 2013 11:29:19 +0100 Subject: 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 Signed-off-by: Mel Gorman Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Srikar Dronamraju Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1381141781-10992-42-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'kernel/sched') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 09aac90df89..aa561c8dc89 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; -- cgit v1.2.3-70-g09d2