[PATCH 1/2] sched: fix cast on power utilization calculation and usediv_u64

[Alex Shi]

Now explicit casting is done when power usage variable (putil) is
calculated.
div_u64 is optimized on u32.

Signed-off-by: Lukasz Majewski <l.majewski@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx>
---
 kernel/sched/fair.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 09ae48a..3a4917c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1504,8 +1504,8 @@ static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
 	__update_tg_runnable_avg(&rq->avg, &rq->cfs);
 
 	period = rq->avg.runnable_avg_period ? rq->avg.runnable_avg_period : 1;
-	rq->util = (u64)(rq->avg.runnable_avg_sum << SCHED_POWER_SHIFT)
-				/ period;
+	rq->util = div_u64(((u64)rq->avg.runnable_avg_sum << SCHED_POWER_SHIFT),
+				period);
 }
 
 /* Add the load generated by se into cfs_rq's child load-average */
@@ -3407,8 +3407,8 @@ static int is_sd_full(struct sched_domain *sd,
 		/* p maybe a new forked task */
 		putil = FULL_UTIL;
 	else
-		putil = (u64)(p->se.avg.runnable_avg_sum << SCHED_POWER_SHIFT)
-				/ (p->se.avg.runnable_avg_period + 1);
+		putil = div_u64(((u64)p->se.avg.runnable_avg_sum << SCHED_POWER_SHIFT),
+				p->se.avg.runnable_avg_period + 1);
 
 	/* Try to collect the domain's utilization */
 	group = sd->groups;
@@ -3463,9 +3463,11 @@ find_leader_cpu(struct sched_group *group, struct task_struct *p, int this_cpu,
 	int vacancy, min_vacancy = INT_MAX;
 	int leader_cpu = -1;
 	int i;
+
 	/* percentage of the task's util */
-	unsigned putil = (u64)(p->se.avg.runnable_avg_sum << SCHED_POWER_SHIFT)
-				/ (p->se.avg.runnable_avg_period + 1);
+	unsigned putil;
+	putil = div_u64(((u64)p->se.avg.runnable_avg_sum << SCHED_POWER_SHIFT),
+				p->se.avg.runnable_avg_period + 1);
 
 	/* bias toward local cpu */
 	if (cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p)) &&
-- 
1.7.12


-- 
Thanks
    Alex
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