sched/numa: Select a preferred node with the most numa hinting faults
This patch selects a preferred node for a task to run on based on the
NUMA hinting faults. This information is later used to migrate tasks
towards the node during balancing.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
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/1381141781-10992-21-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0bb3e0a..9efd34f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -879,7 +879,8 @@
static void task_numa_placement(struct task_struct *p)
{
- int seq;
+ int seq, nid, max_nid = -1;
+ unsigned long max_faults = 0;
if (!p->mm) /* for example, ksmd faulting in a user's mm */
return;
@@ -889,7 +890,19 @@
p->numa_scan_seq = seq;
p->numa_scan_period_max = task_scan_max(p);
- /* FIXME: Scheduling placement policy hints go here */
+ /* Find the node with the highest number of faults */
+ for_each_online_node(nid) {
+ unsigned long faults = p->numa_faults[nid];
+ p->numa_faults[nid] >>= 1;
+ if (faults > max_faults) {
+ max_faults = faults;
+ max_nid = nid;
+ }
+ }
+
+ /* Update the tasks preferred node if necessary */
+ if (max_faults && max_nid != p->numa_preferred_nid)
+ p->numa_preferred_nid = max_nid;
}
/*