Re: [.32-rc3] scheduler: iwlagn consistently high in "waiting for CPU"

[Frans Pop]

On Monday 05 October 2009, Frans Pop wrote:
> 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.

If I give the system some work to do (like compiling a kernel), the 
latencies on iwlagn and phy0 disappear (values < 5 ms).
Is this related to ondemand frequency scaling?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/