From: Joonsoo Kim <iamjoonsoo....@lge.com>
Remove one division operation in find_busiest_queue() by using
crosswise multiplication:
wl_i / power_i > wl_j / power_j :=
wl_i * power_j > wl_j * power_i
Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>
[peterz: expanded changelog]
Signed-off-by: Peter Zijlstra <pet...@infradead.org>
---
kernel/sched/fair.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5018,7 +5018,7 @@ static struct rq *find_busiest_queue(str
struct sched_group *group)
{
struct rq *busiest = NULL, *rq;
- unsigned long max_load = 0;
+ unsigned long busiest_load = 0, busiest_power = SCHED_POWER_SCALE;
int i;
for_each_cpu(i, sched_group_cpus(group)) {
@@ -5049,10 +5049,9 @@ static struct rq *find_busiest_queue(str
* the load can be moved away from the cpu that is potentially
* running at a lower capacity.
*/
- wl = (wl * SCHED_POWER_SCALE) / power;
-
- if (wl > max_load) {
- max_load = wl;
+ if (wl * busiest_power > busiest_load * power) {
+ busiest_load = wl;
+ busiest_power = power;
busiest = rq;
}
}
--
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