From: Frans Pop <elendil@planet.nl>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: [.32-rc3] scheduler: iwlagn consistently high in "waiting for CPU"
Date: Mon, 5 Oct 2009 15:00:54 +0200
Cc: Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <peterz@infradead.org>,
	linux-wireless@vger.kernel.org
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Message-Id: <200910051500.55875.elendil@planet.nl>
Sender: linux-wireless-owner@vger.kernel.org

With .32-rc3 I'm getting occasional skips from amarok while playing music 
from an NFS share (3 today so far), something I've not had in a long time.

The reason looks to be that latencytop consistently shows 'iwlagn' as the 
top affected process with "Scheduler: waiting for CPU".
Values of 100-140 ms occur frequently, but I've also seen higher values 
(180, 207). I don't remember seeing iwlagn high in the list before, but I 
have not checked earlier kernels yet.

Added to that 'phy0' also frequently shows high with values of 25-75 ms.

The system is otherwise essentially idle. Other processes typically show a 
latency < 5 ms.

System: HP 2510p notebook, x86_64, Core2 Duo, Debian stable

Cheers,
FJP