[linux-audio-user] Success: Tascam US-122 and Laptop

[Lee Revell]

On Sat, 2005-03-26 at 13:32 +0000, Steve Fosdick wrote:
> On 24/03/05 19:03:50, Lee Revell wrote:
> > On Thu, 2005-03-24 at 13:49 -0500, Lee Revell wrote:
> > > Is the USB irq shared with anything?
> > 
> > Never mind, I see that it is shared, and with a pretty "heavy" device
> > (the network card).
> > 
> > Is this the case for everyone who is having the problem?
> > 
> > Does disconnecting the network cable help?
> 
> I had previously tried disconnecting the network cable but this didn't
> seem to make any difference.  I also tried the apci_irq_balance option
> but that didn't solve it either.
> 
> I have finally got jackd to run without complain by disabling CPU
> frequency scaling, i.e. having the CPU run at 1.2Ghz all the time rather
> than switch to 600Mhz when it doesn't appear that there is anything
> going on.
> 
> I wonder if this means the code path between the USB interrupt and jackd
> being woken up is very long so as to require the full 1.2Ghz or whether
> it is just a case of the frequency switching upsetting some time
> calculations.

Oh, well, of course.  JACK does not work with CPU frequency scaling.
You need to run it at full speed.  This is something of a FAQ.

Lee