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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>
This commit is contained in:
Rik van Riel 2013-10-07 11:29:19 +01:00 committed by Ingo Molnar
parent 2c8a50aa87
commit e1dda8a797
1 changed files with 5 additions and 6 deletions
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11
kernel/sched/fair.c
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@ -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;