linux-kernel - [PATCH 1/2] sched: reduce calculation effort in fix_small

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Date:	Fri, 14 Jun 2013 14:14:18 +0800
From:	Lei Wen <leiwen@...vell.com>
To:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	<mingo@...hat.com>, <leiwen@...vell.com>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] sched: reduce calculation effort in fix_small_imbalance

Actually all below item could be repalced by scaled_busy_load_per_task
	(sds->busiest_load_per_task * SCHED_POWER_SCALE)
		/sds->busiest->sgp->power;

Signed-off-by: Lei Wen <leiwen@...vell.com>
---
 kernel/sched/fair.c |   19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c61a614..28052fa 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4727,20 +4727,17 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
 	pwr_now /= SCHED_POWER_SCALE;
 
 	/* Amount of load we'd subtract */
-	tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
-		sds->busiest->sgp->power;
-	if (sds->max_load > tmp)
+	if (sds->max_load > scaled_busy_load_per_task) {
 		pwr_move += sds->busiest->sgp->power *
-			min(sds->busiest_load_per_task, sds->max_load - tmp);
-
-	/* Amount of load we'd add */
-	if (sds->max_load * sds->busiest->sgp->power <
-		sds->busiest_load_per_task * SCHED_POWER_SCALE)
-		tmp = (sds->max_load * sds->busiest->sgp->power) /
-			sds->this->sgp->power;
-	else
+			min(sds->busiest_load_per_task,
+				sds->max_load - scaled_busy_load_per_task);
 		tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
 			sds->this->sgp->power;
+	} else
+		tmp = (sds->max_load * sds->busiest->sgp->power) /
+			sds->this->sgp->power;
+
+	/* Amount of load we'd add */
 	pwr_move += sds->this->sgp->power *
 			min(sds->this_load_per_task, sds->this_load + tmp);
 	pwr_move /= SCHED_POWER_SCALE;
-- 
1.7.10.4

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