sched/numa: Simplify task_numa_compare()

When a task is part of a numa_group, the comparison should always use
the group weight, in order to make workloads converge.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: chegu_vinod@hp.com
Cc: mgorman@suse.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1403538378-31571-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -1154,7 +1154,7 @@ static void task_numa_compare(struct task_numa_env *env,
 	struct task_group *tg;
 	long src_load, dst_load;
 	long load;
-	long imp = (groupimp > 0) ? groupimp : taskimp;
+	long imp = env->p->numa_group ? groupimp : taskimp;
 
 	rcu_read_lock();
 	cur = ACCESS_ONCE(dst_rq->curr);
@@ -1192,11 +1192,6 @@ static void task_numa_compare(struct task_numa_env *env,
 			 * itself (not part of a group), use the task weight
 			 * instead.
 			 */
-			if (env->p->numa_group)
-				imp = groupimp;
-			else
-				imp = taskimp;
-
 			if (cur->numa_group)
 				imp += group_weight(cur, env->src_nid) -
 				       group_weight(cur, env->dst_nid);