[patch v6 16/21] sched: pull all tasks from source group

[Alex Shi <alex.shi@intel.com>]

In power balance, we hope some sched groups are fully empty to save
CPU power of them. So, we want to move any tasks from them.

Signed-off-by: Alex Shi <alex.shi@intel.com>
---
 kernel/sched/fair.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index adccdb8..d25fb3b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5115,7 +5115,9 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 		 * When comparing with imbalance, use weighted_cpuload()
 		 * which is not scaled with the cpu power.
 		 */
-		if (capacity && rq->nr_running == 1 && wl > env->imbalance)
+		if (rq->nr_running == 0 ||
+			(!(env->flags & LBF_POWER_BAL) && capacity &&
+				rq->nr_running == 1 && wl > env->imbalance))
 			continue;
 
 		/*
@@ -5218,7 +5220,8 @@ redo:
 
 	ld_moved = 0;
 	lb_iterations = 1;
-	if (busiest->nr_running > 1) {
+	if (busiest->nr_running > 1 ||
+		(busiest->nr_running == 1 && env.flags & LBF_POWER_BAL)) {
 		/*
 		 * Attempt to move tasks. If find_busiest_group has found
 		 * an imbalance but busiest->nr_running <= 1, the group is
-- 
1.7.12