sched/numa: Take false sharing into account when adapting scan rate

Scan rate is altered based on whether shared/private faults dominated.
task_numa_group() may detect false sharing but that information is not
taken into account when adapting the scan rate. Take it into account.

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/1381141781-10992-58-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -1381,7 +1381,8 @@ static void double_lock(spinlock_t *l1, spinlock_t *l2)
 	spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
 }
 
-static void task_numa_group(struct task_struct *p, int cpupid, int flags)
+static void task_numa_group(struct task_struct *p, int cpupid, int flags,
+			int *priv)
 {
 	struct numa_group *grp, *my_grp;
 	struct task_struct *tsk;
@@ -1447,6 +1448,9 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags)
 	if (flags & TNF_SHARED)
 		join = true;
 
+	/* Update priv based on whether false sharing was detected */
+	*priv = !join;
+
 	if (join && !get_numa_group(grp))
 		join = false;
 
@@ -1545,7 +1549,7 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
 	} else {
 		priv = cpupid_match_pid(p, last_cpupid);
 		if (!priv && !(flags & TNF_NO_GROUP))
-			task_numa_group(p, last_cpupid, flags);
+			task_numa_group(p, last_cpupid, flags, &priv);
 	}
 
 	/*