[LAU] Balance between performance and noise

[Fernando Lopez-Lezcano]

On 12/09/2010 09:35 AM, Robin Gareus wrote:
> On 11/27/10 13:11, Arnold Krille wrote:
>> Set ther cpu-governor to performance (so it doesn't switch frequencies which
>> produces xruns) but reduce the maximum allowed frequency.
> what kernel are you running?
>
> I do have realtime-kernels (2.6.31.12-rt21, 2.6.33.7-rt29) running on 4
> PCs/Laptops (Intel core duo 32bit, Intel Core 2 Duo 64bit, Atom and an
> Intel-i5) and on none of them frequency-scaling ever caused any x-runs.
> The ondemand governor is ruling them all.

Lucky you! :-) I have problems here running rt29 on a Lenovo T510 
laptop. Frequency scaling causes xruns. And I found (after wasting a lot 
of time on other possible causes) that setting the governor to 
"Performance" was actually not enough. You had to actually stop the 
cpuspeed daemon and then the xruns would just go away.

>  ..what does cause problems here is FSBus frequency scaling, I've
>  disabled that in the BIOS.

Good to know! I suspect my laptop will not have that degree of configurability in the BIOS but I'll try that with out desktops.

-- Fernando


> It /might/ be an issue with other CPUs or mainboards.. or non-RT
> systems, or with extreme low latency. But I'm not seeing any issues with
> freq scaling even at 32*2 at 48kHz.
>
> ciao,
> robin
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