[PlanetCCRMA] Wondering about upgrading my CPU

JOHN LYON jalyon at shaw.ca
Mon Jun 1 13:03:46 PDT 2009

Hi Everybody,

I've been struggling with recording on Linux for a while now, and at last I seem to be getting close to where I want to be.  

I'm using Fedora core 10, PlanetCCRMA apps, ardour-2.8-1.fc10.i386, ffado-2.0-0.6.rc1.fc10.ccrma.i386
libffado-2.0-0.6.rc1.fc10.ccrma.i386, a Focusrite 10 26,  qjackctl-0.3.4-1.fc10.i386, jack-audio-connection-kit-1.9.2-2.fc10.ccrma.i386.  I'm using the edge kernel because my motherboard is an ASUS P5QL Pro, which doesn't work with the 2.6.27 kernels.  So far so good.  

My hardware includes the focusrite IO 26 and a Behringer BCF2000 control surface, which is particularly helpful as I am visually impaired and have trouble with the small mouse pointer and the small print used in Ardour.  

My problem is that I'm still getting xruns.  I use the lightweight window manager XFCE, and I shut off network services when I am recording, (NetworkManager, sshd, ntpd, vsftp, httpd, etc.  This all helps; sometimes I can record at pretty low latencies with no xruns.  But not always. 

Oh, here's an example of how I call jackd:

/usr/bin/pasuspender --s | /usr/bin/jackd -R -P70 -t5000 -dfirewire -r44100 -p128 -n3 &

Yes, I can set -p higher, but I've experienced xruns recording, say 4 or 5 mics in ardour at even -p512 or -p1024.  

I do understand that there is quite a bit of trial and error involved in trying to find the best settings for jackd, and I've tried many different -p and -n settings to see if I can find some low latency with no xruns.  

My CPU is an inexpensive Pentium D (although I believe it is running at 3 Ghz).  I'm wondering what I can expect if I upgrade to, say, a relatively fast Core 2 duo or a quad core CPU.  Does anyone have information about how this might affect my situation?  My understanding from years back is that the Linux kernel does a good job at taking advantage of multiple CPUs, and presumably, multiple cores, so I am hopeful that a newer, faster CPU might solve my latency and xrun issues. 

Your thoughts and comments would be appreciated.


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