Kernel-lowlatency vs kernel-rt

[Len Ovens]

On Fri, November 2, 2012 3:58 pm, Ralf Mardorf wrote:
> Hi :)
>
> on Ubuntu Studio Quantal I switched to
> $ uname -a
> Linux qrc 3.6.5-rt14 #1 SMP PREEMPT RT Fri Nov 2 21:36:37 CET 2012
> x86_64 x86_64 x86_64 GNU/Linux
>
> A kernel-rt seems to be much better on my machine.
>
> With the kernel-lowlatency for a very small audio session, CPU usage
> "< 10%", I get xruns with
>
> sample_rate=48000
> frames_period=512
>
> Now, with the kernel-rt everything seems to be [Ok] with
>
> frames_period=256
>
> but with frames_period=128 I get xruns again.

Correct me if I am wrong, but are you not running two M-audio cards for
midi as well? I think if I remember right, they are ice1712 cards. Does
the midi part of it need the ice1712 kernel driver? That is, would you
still get midi if the ice1712 driver was black listed or unloaded? I'm
just wondering if ALSA is using cpu time servicing 20 inputs at 48000 hrz
for something you are not using. (24bits of silence is still 24 bits of
throughput and the ice chips are 10 channels each) I don't know how ALSA
handles unused (unconnected) ports. I do know that jack and pulse take
just as much time dealing with all the ports even the ones you don't
happen to be using.


-- 
Len Ovens
www.OvenWerks.net