linux-kernel - Re: [patch 3/3] sched: move sched_avg_update() to update_cpu

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Message-Id: <1282596171.2694.3.camel@sbsiddha-MOBL3>
Date:	Mon, 23 Aug 2010 13:42:51 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"mingo@...e.hu" <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"chris@...stnet.net" <chris@...stnet.net>,
	"debian00@...ceadsl.fr" <debian00@...ceadsl.fr>,
	"hpa@...or.com" <hpa@...or.com>,
	"jonathan.protzenko@...il.com" <jonathan.protzenko@...il.com>,
	"mans@...sr.com" <mans@...sr.com>,
	"psastudio@...l.ru" <psastudio@...l.ru>,
	"rjw@...k.pl" <rjw@...k.pl>,
	"stephan.eicher@....de" <stephan.eicher@....de>,
	"sxxe@....de" <sxxe@....de>,
	"thomas@...hlinux.org" <thomas@...hlinux.org>,
	"venki@...gle.com" <venki@...gle.com>,
	"wonghow@...il.com" <wonghow@...il.com>
Subject: Re: [patch 3/3] sched: move sched_avg_update() to update_cpu_load()

On Fri, 2010-08-20 at 06:47 -0700, Peter Zijlstra wrote:
> breaks CONFIG_SMP=n builds..
> 
>   CC      kernel/sched.o
> /usr/src/linux-2.6/kernel/sched.c: In function ‘update_cpu_load’:
> /usr/src/linux-2.6/kernel/sched.c:3186: error: implicit declaration of function ‘sched_avg_update’  CC      kernel/sched.o
> /usr/src/linux-2.6/kernel/sched.c: In function ‘update_cpu_load’:
> /usr/src/linux-2.6/kernel/sched.c:3186: error: implicit declaration of function ‘sched_avg_update’

Updated patch appended. Thanks.
---

From: Suresh Siddha <suresh.b.siddha@...el.com>
Subject: sched: move sched_avg_update() to update_cpu_load()

Currently sched_avg_update() (which updates rt_avg stats in the rq) is getting
called from scale_rt_power() (in the load balance context) which doesn't take
rq->lock.

Fix it by moving the sched_avg_update() to more appropriate update_cpu_load()
where the CFS load gets updated aswell.

Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---
 kernel/sched.c      |    6 ++++++
 kernel/sched_fair.c |    2 --
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 41541d7..f95bbbe 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1294,6 +1294,10 @@ static void resched_task(struct task_struct *p)
 static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
 {
 }
+
+static void sched_avg_update(struct rq *rq)
+{
+}
 #endif /* CONFIG_SMP */
 
 #if BITS_PER_LONG == 32
@@ -3182,6 +3186,8 @@ static void update_cpu_load(struct rq *this_rq)
 
 		this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i;
 	}
+
+	sched_avg_update(this_rq);
 }
 
 static void update_cpu_load_active(struct rq *this_rq)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 806d1b2..a2bf7bd 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -2268,8 +2268,6 @@ unsigned long scale_rt_power(int cpu)
 	struct rq *rq = cpu_rq(cpu);
 	u64 total, available;
 
-	sched_avg_update(rq);
-
 	total = sched_avg_period() + (rq->clock - rq->age_stamp);
 	available = total - rq->rt_avg;
 


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