[sc-users] linux sc performance again

[Matthew Yee-King]

George Bashi wrote:
> Hey,
> 
> The low-latency and realtime stuff does make a HUGE difference...
> Testing on my laptop (stock ubuntu edgy kernel, realtime jack, Athlon
> XP 2500 / 768mb ram, tonnes of stuff running in the background) I got
> to 851 before the machine locked up - so I bet with those machines
> it'd be a lot higher!
> 
> Try getting jack to run realtime (try "jackd -R" as root is the
> quickest way) and see if that helps. Also, the scheduler can play a
> part in it too - I'm not sure what the default is in debian but try
> passing elevator=cfq as an argument to the kernel (with grub or lilo).
> 
> If I get a chance I'll test next week with different schedulers and
> realtime on/off.
> 


Hi George

Cheers for the into. I've been using linux audio for years but have
never really bothered with the pre-emptive/ real time kernel stuff until
now as I've had low enough latency and glitch free audio- However, if I
can run 3 times as many ugens, then i'm in!

I have installed a pre-emption enabled kernel from the studio-64
repository (a debian based distro for people doing linux audio on 64 bit
platforms) along with their version of jackd/ libjack. I've run jackd
with rt privileges and even mucked around with the irgs after:

http://tapas.affenbande.org/?page_id=40

but still I have more or less the same performance I had at the start.
Anything else I can do here? Did you compile your own jack with any
weird flags? Have you mucked around with the irqs? How can I test if
pre-emption is working on my kernel?

cheers

matthew