sched: fix load scaling in group balancing

doing the load balance will change cfs_rq->load.weight (that's the whole point)
but since that's part of the scale factor, we'll scale back with a different
amount.

Weight getting smaller would result in an inflated moved_load which causes
it to stop balancing too soon.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 4 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 865cb53a7ccf..734e4c556fcb 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1444,6 +1444,8 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
 
         list_for_each_entry(tg, &task_groups, list) {
                 struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
+                unsigned long busiest_h_load = busiest_cfs_rq->h_load;
+                unsigned long busiest_weight = busiest_cfs_rq->load.weight;
                 long rem_load, moved_load;
 
                 /*
@@ -1452,8 +1454,8 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
                 if (!busiest_cfs_rq->task_weight)
                         continue;
 
-                rem_load = rem_load_move * busiest_cfs_rq->load.weight;
-                rem_load /= busiest_cfs_rq->h_load + 1;
+                rem_load = rem_load_move * busiest_weight;
+                rem_load /= busiest_h_load + 1;
 
                 moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
                                 rem_load, sd, idle, all_pinned, this_best_prio,
@@ -1462,8 +1464,8 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
                 if (!moved_load)
                         continue;
 
-                moved_load *= busiest_cfs_rq->h_load;
-                moved_load /= busiest_cfs_rq->load.weight + 1;
+                moved_load *= busiest_h_load;
+                moved_load /= busiest_weight + 1;
 
                 rem_load_move -= moved_load;
                 if (rem_load_move < 0)