path: root/kernel/sched
diff options
authorMel Gorman <mgorman@suse.de>2012-11-19 10:59:15 +0000
committerMel Gorman <mgorman@suse.de>2012-12-11 14:42:51 +0000
commite14808b49f55e0e1135da5e4a154a540dd9f3662 (patch)
treed66708455dcc1b6e2e15937d732ab12c121e623a /kernel/sched
parenta8f6077213d285ca08dbf6d4a67470787388138b (diff)
mm: numa: Rate limit setting of pte_numa if node is saturated
If there are a large number of NUMA hinting faults and all of them are resulting in migrations it may indicate that memory is just bouncing uselessly around. NUMA balancing cost is likely exceeding any benefit from locality. Rate limit the PTE updates if the node is migration rate-limited. As noted in the comments, this distorts the NUMA faulting statistics. Signed-off-by: Mel Gorman <mgorman@suse.de>
Diffstat (limited to 'kernel/sched')
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7727b016157..37e895a941a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -27,6 +27,7 @@
#include <linux/profile.h>
#include <linux/interrupt.h>
#include <linux/mempolicy.h>
+#include <linux/migrate.h>
#include <linux/task_work.h>
#include <trace/events/sched.h>
@@ -861,6 +862,14 @@ void task_numa_work(struct callback_head *work)
if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
+ /*
+ * Do not set pte_numa if the current running node is rate-limited.
+ * This loses statistics on the fault but if we are unwilling to
+ * migrate to this node, it is less likely we can do useful work
+ */
+ if (migrate_ratelimited(numa_node_id()))
+ return;
start = mm->numa_scan_offset;
pages = sysctl_numa_balancing_scan_size;
pages <<= 20 - PAGE_SHIFT; /* MB in pages */