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

Simon W. Fielding s.fielding at wmcce.org
Tue Feb 10 05:53:01 EST 2009


>> 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.

Cheers,
Simon
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