[LAU] Phonic Helix Board 12 FireWireMKIIcompatibility(linux/ffado)

pete shorthose zenadsl6252 at zen.co.uk
Tue Feb 10 09:05:21 EST 2009

On Tue, 10 Feb 2009 10:53:01 -0000
"Simon W. Fielding" <s.fielding at wmcce.org> wrote:

> >> jackd -R -dfirewire -r96000 -p16 -n3 ... jackd won't even start - uses too much CPU
> >> jackd -R -dfirewire -r96000 -p32 -n3 ... jackd won't even start - uses too much CPU
> >> 
> >> Both of the above seem to sometimes leave the 1394 bus in a strange state. A forced bus reset using
> >> gscanbus seems to fix it.
> >> 
> >> jackd -R -dfirewire -r96000 -p64 -n3 ... jackd starts - uses approx 70% CPU with xruns every 10-20 seconds
> >> jackd -R -dfirewire -r96000 -p128 -n3 ... jackd starts - uses approx 50% CPU - no xruns
> >> jackd -R -dfirewire -r96000 -p256 -n3 ... jackd starts - uses approx 45% CPU - no xruns
> >> jackd -R -dfirewire -r96000 -p512 -n3 ... jackd starts - uses approx 25% CPU - no xruns
> >
> >Hmm this is good and bad news. That it works and does so without xruns is great but I'm not sure what
> >to make of the processor usage. For comparison, if I setup my inspiron 9400 to use -r96000 -p256 -n3
> >it uses less than a tenth of what you see. Mine has a core 2 duo t7200 2ghz CPU and an intel HDA 
> >but even so.. 45% seems pretty onerous and surely not an indication that my system is 10 times faster than yours.
> This is a fairly gutless and underpowered machine for this sort of thing. It's also completely untuned
> for audio work - just an out of the box FC10 and CCRMA build, gnome etc. I would normally only use it
> for running soft synths etc, not to try anything like this with.
> FWIW, without the Phonic, but with the built in ICH6, jackd -R -dalsa -dhw:0,0 -r96000 -p256 -n3 uses between 1% and 3% CPU,
> idling under the same conditions as before.

All of which indicates that I would see similar results on my system unless there is some kind of 
bug or problem that only affects you. In effect, you are seeing  >1000% penalty for the use of firewire. 
Which is pretty horrific. 

I've also been looking around for a suitable expresscard firewire adapter and I've come across some suggestions
that I won't get a firewire audio device working properly on this laptop (Inspiron 9400) regardless of what adapter
I buy.  o_O


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