linux-kernel - [PATCH V5 6/8] sched: rewrite update_cpu_load

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Message-Id: <1397616209-27275-7-git-send-email-alex.shi@linaro.org>
Date:	Wed, 16 Apr 2014 10:43:27 +0800
From:	Alex Shi <alex.shi@...aro.org>
To:	mingo@...hat.com, peterz@...radead.org, morten.rasmussen@....com,
	vincent.guittot@...aro.org, daniel.lezcano@...aro.org,
	efault@....de
Cc:	wangyun@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	mgorman@...e.de
Subject: [PATCH V5 6/8] sched: rewrite update_cpu_load_nohz

After change to sched_avg, the cpu load in idle exit was decayed.
So, it maybe near zero if waking a long time sleep task, or, a full
non-decay load if waking a new forked task. Then, we can use it to
reflect the cpu load, don't need to pretend 0.

Signed-off-by: Alex Shi <alex.shi@...aro.org>
---
 kernel/sched/proc.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index 057bb9b..383c4ba 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -461,28 +461,13 @@ void update_idle_cpu_load(struct rq *this_rq)
 }
 
 /*
- * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
+ * Called from tick_nohz_idle_exit()
  */
 void update_cpu_load_nohz(void)
 {
 	struct rq *this_rq = this_rq();
-	unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
-	unsigned long pending_updates;
-
-	if (curr_jiffies == this_rq->last_load_update_tick)
-		return;
 
-	raw_spin_lock(&this_rq->lock);
-	pending_updates = curr_jiffies - this_rq->last_load_update_tick;
-	if (pending_updates) {
-		this_rq->last_load_update_tick = curr_jiffies;
-		/*
-		 * We were idle, this means load 0, the current load might be
-		 * !0 due to remote wakeups and the sort.
-		 */
-		__update_cpu_load(this_rq, 0);
-	}
-	raw_spin_unlock(&this_rq->lock);
+	update_idle_cpu_load(this_rq);
 }
 #endif /* CONFIG_NO_HZ */
 
-- 
1.8.3.2

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