linux-kernel - [PATCH v2 3/3] nohz_full: update cpu load fix in nohz

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Date:	Tue,  3 Dec 2013 20:35:12 +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,
	fweisbec@...il.com, linux@....linux.org.uk, tony.luck@...el.com,
	fenghua.yu@...el.com, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, pjt@...gle.com,
	fengguang.wu@...el.com
Cc:	james.hogan@...tec.com, alex.shi@...aro.org, jason.low2@...com,
	viresh.kumar@...aro.org, hanjun.guo@...aro.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] nohz_full: update cpu load fix in nohz_full

We are not always 0 when update nohz cpu load, after nohz_full enabled.
But current code still treat the cpu as idle. that is incorrect.
Fix it to use correct cpu_load.

Signed-off-by: Alex Shi <alex.shi@...aro.org>
---
 kernel/sched/proc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index 16f5a30..f1441f0 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -568,8 +568,14 @@ void update_cpu_load_nohz(void)
 		/*
 		 * We were idle, this means load 0, the current load might be
 		 * !0 due to remote wakeups and the sort.
+		 * or we may has only one task and in NO_HZ_FULL, then still use
+		 * normal cpu load.
 		 */
-		__update_cpu_load(this_rq, 0, pending_updates);
+		if (this_rq->cfs.h_nr_running) {
+			unsigned load = get_rq_runnable_load(this_rq);
+			__update_cpu_load(this_rq, load, pending_updates);
+		} else
+			__update_cpu_load(this_rq, 0, pending_updates);
 	}
 	raw_spin_unlock(&this_rq->lock);
 }
-- 
1.8.1.2

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