linux-kernel - [PATCH] sched/pelt: use shift operation instead of division operation

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Message-Id: <1582515055-14515-1-git-send-email-qiwuchen55@gmail.com>
Date:   Mon, 24 Feb 2020 11:30:55 +0800
From:   qiwuchen55@...il.com
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de
Cc:     linux-kernel@...r.kernel.org, chenqiwu <chenqiwu@...omi.com>
Subject: [PATCH] sched/pelt: use shift operation instead of division operation

From: chenqiwu <chenqiwu@...omi.com>

Use shift operation to calculate the periods instead of division,
since shift operation is more efficient than division operation.

Signed-off-by: chenqiwu <chenqiwu@...omi.com>
---
 kernel/sched/pelt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index bd006b7..ac79f8e 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -114,7 +114,7 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
 	u64 periods;
 
 	delta += sa->period_contrib;
-	periods = delta / 1024; /* A period is 1024us (~1ms) */
+	periods = delta >> 10; /* A period is 1024us (~1ms) */
 
 	/*
 	 * Step 1: decay old *_sum if we crossed period boundaries.
-- 
1.9.1