Re: xruns with m-audio fast track pro on fedora 8 ccrma

On Tue, 2008-01-22 at 13:29 +0100, hitmuri@... wrote:

Thanks for answering (maybe i could have asked on the linuxmao.org forum
too ;) ) .

I tried to change the rtirq script but it doesn't seem to make any
difference. But while looking at the rt priorities, i noticed that the
highest priority for usb was given to the irq 16 and cat /proc/interrupts
tells me that on irq 16 there's uhci_hcd:usb3 and NVIDIA !!!
When i plug my usb soundcard , it's always on irq 20.
So it looks like the highest priority is given to the graphics card .

Because it shares the interrupt with the usb controller which may have
an audio card attached...

What do you see in "cat /proc/interrupts" for other interrupts? Do you
perhaps have another usb controller that does not share an interrupt
with the graphics controller?

Is this the problem to solve ?

It may be, hard to know for shure. 

-- Fernando

2008/1/22, hitmuri@... hitmuri@...:

Hi everyone,

i have posted this on the planet ccrma list before, but i don't think
it's
a distribution problem. I get xruns when using a m-audio fast track pro
usb soundcard  at 44100Hz, frames/period=64 (same with 128, i need low
latency) ,periods/buffer=2 with my new laptop when i have for example
freewheeling, tapeutape and jack-rack running (xruns seem to appear when
the dsp load rises, i've got none when using tapeutape alone for
example).
Some of them were related to the latest ccrma kernel, and they
disappeared
with a previous one. For the other ones, i have 4 ideas :

1) latency timer :
doing lspci, all the latencies show 0 , even when i set them to antoher
value with setpci. But with dmesg, i can see that at startup they are
set
to 64.
Fernando Lopez-Lezcano told me that on some hardware latency timer
couldn't be changed and that 64 could be enough actually.
(forgot to say that the usb irq isn't shared)

So it looks like i can't do anything for that.

2) rtc :
At startup i have a message from udev : Node Symlink... node /dev/rtc
already exists , link to /dev/rtc0 will not overwrite it.

I got this message too, but I don't know if there is any impact on the
sound
system.

3) soundcard power

The fast track pro can be powered by usb or by an external power supply.
Mine is usb powered for now. Is this a problem ?

4) rtirq
I noticed that in the rtirq script , i have these lines:
RTIRQ_NAME_LIST="rtc snd usb i8042"
RTIRQ_NON_THREADED="rtc snd"
Do they need to be changed when using a usb soundcard ?

If your sound card works with USB, you can write this :

RTIRQ_NAME_LIST="rtc usb i8042"
RTIRQ_NON_THREADED="rtc usb"

Then you restart the script  and echo his status

$ sudo /etc/init.d/rtirq restart
$ /etc/init.d/rtirq status

You will see the priority on each IRQ. Then you have to connect your sound
card on the USB port wich has the best priority.

If anyone has an idea on that...

Sorry it was quite long !!

Thanks

Flo

Hope this help you,
cheers,

Mysth-R

--
*
***************************************************************************************
*  {^_^} Mysth-R {^_^}
*
* http://myspace.com/mysthr
* http://myspace.com/aideauditive
* http://mysthr.free.fr  => Site dédié à l'audio sous Fedora/PlanetCCRMA.
*
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