[LAU] eliminating xruns on 64-bit Arch ?

[gene heskett]

On Thursday, December 15, 2011 10:17:37 AM Dave Phillips did opine:

> On 12/15/2011 07:52 AM, Mac wrote:
> > ...I then stumbled on AVLinux. I installed it, fired up Jack and
> > Ardour...and it just worked. So that's what I've been using for
> > sometime now. This is of course a single data point and I have not had
> > the occasion to do try anything with later releases.
> 
> Hi Mac,
> 
> Thanks for the note, but I'm already using AVLinux on my laptop. I have
> three machines here, each running a different distro, and Arch is the
> 64-bit distribution of choice (the 32-bit others are Ubuntu 10.04 and
> AVLinux). 64 Studio was a rock-solid champ of a system until it aged
> beyond rejuvenation. Now I want another rock-solid nVidia-friendly
> xrun-less 64-bit system, and I'm wondering if it's even possible with
> the current 3.x kernels. However, I shall persist. :)
> 
New bee here, to this list, but not to linux, I have been windows free 
since RH5.0 in the late '90's.

In my experiences with EMC (electronic Machine control, as in cnc lathes 
and milling machines), which when driving stepper motors, needs absolute 
low latency and uses the RTAI version kernels to achieve this as the output 
loop timing when driving steppers may be as low as 20 microseconds per pass 
through the output loop, I've found that the nvidia blob and what you would 
call an x-run-less system, are going to be mutually exclusive because the 
nvidia blob locks out the IRQ's for extended (sometimes in excess of 200 
milliseconds) periods.  So even an nvidia card gets driven with the vesa 
driver which doesn't do that.

For that reason, I currently have an ATI X-1650 card in that box, using the 
linux ati/radeon driver.  This combo actually gives me about the same 
latency's as the vesa driver does, but with a much more accurate display 
drawing.  The vesa driver is so slow that the backplot drawing takes 
shortcuts when the tool turns a corner, the linux ati/radeon combo does a 
much better job in that regard.

And no, I don't own stock in amd/ati. :)

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene>
Somebody ought to cross ball point pens with coat hangers so that the
pens will multiply instead of disappear.