[LAU] Jack vs. Alsa, PianoTeq demo: Alsa wins!

[david]

Aaron Krister Johnson wrote:
> Hi all,
> 
> I just wanted to report that I finally have joy regarding the
> Pianoteq/JACK issues I've been plagued by!
> 
> What worked for me is disabling 'CPU overload detection' (in
> Pianoteq). I had already disabled 'multicore' in the same 'Performance
> dialog', and just to be extra sure, I took all of my WIFI connections
> offline, as well as unloading the drivers for wireless all together
> while I played (in this case, it was 'ndiswrapper'). I don't think it
> was causing a problem, but every extra thing that eats CPU or memory
> that I don't need while playing doesn't hurt to take offline.

I've heard that wireless drivers can cause many xruns because they 
periodically rescan for available wireless connections (even if the 
wireless card's external antenna is turned off). When their scan takes 
much time, apparently, and they hog things while doing it.

> Just FYI, for anyone who can find the information useful, my setup:
> 
> * ASUS EEEPC 1000HE
> * Lexicon Lambda outboard USB sound interface, IRQ made RT priority
> with 'chrt -p 99 XXXX', XXXX being the process ID of the IRQ handling
> the USB sound interface, found with 'cat /proc/interrupts' and 'lsusb'
> * Arch Linux, which I recommend over Ubuntu anyday for minimalists who
> want to squeeze every last drop of bloat (and thus benefit
> performance) out of their boxes.
> * output of 'uname -a' : Linux myhost 2.6.33-rt #1 SMP PREEMPT RT Sat
> Aug 7 09:40:44 UTC 2010 i686 Intel(R) Atom(TM) CPU N280 @ 1.66GHz
> GenuineIntel GNU/Linux
> * output of 'jackd -V': jackd version 0.120.2 tmpdir /dev/shm protocol 24
> * jackd command: 'jackd -dalsa -r44100 -p128 -n3'
> 
> I've heard that many USB interfaces seem to need 3 soft buffer periods
> per hardware buffer periods ('-n3' in the jackd command above). I knew
> this already, and that wasn't my issue, but I'm just saying this to
> other folks who may have problems with outboard USB sound interfaces,

I have to use -n3 with my UCA202.

-- 
David
gnome at hawaii.rr.com
authenticity, honesty, community