[ardour-users] [Fwd: Re: Is 64 bit dual core supported and stable yet?]

Fernando Lopez-Lezcano nando at ccrma.Stanford.EDU
Fri Dec 2 17:53:50 PST 2005

On Fri, 2005-12-02 at 11:20 -0500, George Chan wrote:
> I finally decided on what system to build, that included a dual core
> Athlon.  
> Then I received this email.
> So, I guess, that for now, it would be better to have a Dual CPU Single
> Core Opteron system?
> What do you think?

The latest patch for realtime preemption from Ingo Molnar does not use
the TSC for internal timing in the kernel in the case of the dual core
Athlon X2 cpus (2.6.14-rt12). So the kernel problems do not happen (in
my case I experienced sporadic key repeat problems and random temporary
activations of the screensaver). 

A patch is needed for Jack so that it does not use the TSC for timing
with those cpus, some stuff has been posted to the jackit-devel list but
no definite patch is yet on CVS. 

So things are getting there...
-- Fernando

> ------- Forwarded Message --------
> From: Paul Davis <paul at linuxaudiosystems.com>
> Reply-To: paul at linuxaudiosystems.com
> To: Joel White <cv223 at comcast.net>
> Cc: ardour-users at lists.ardour.org
> Subject: Re: [ardour-users] Is 64 bit dual core supported and stable
> yet?
> Date: Tue, 29 Nov 2005 09:34:28 -0500
> On Mon, 2005-11-28 at 23:15 -0500, Joel White wrote:
> > Even thought the results are good so far, I still get occasional xruns like:
> > 
> > **** alsa_pcm: xrun of at least 118.867 msecs
> > (this particular xrun interrupted a recording with my band, which is 
> > _very_ bad! I was even running capture only and with a longer period, 
> > just to be sure xruns wouldn't happen!)
> > 
> > and the odd:
> > 
> > delay of 1131462.000 usecs exceeds estimated spare time of 5606.000; 
> > restart ...
> > (this type of error comes mostly when audio connections change, but also 
> > at other times, although the delay isn't usually quite so long)
> > 
> >  From my understanding, both of these time periods indicate something 
> > very wrong (an xrun of 118+ msecs?? a delay of 1.13+ _sec_?!?!), but I 
> > haven't been able to track them down, yet.  I've run Ardour recording 8 
> this is caused by a design fault in AMD's dual core offerings. they have
> already made it clear that future designs will rectify the problem.
> there is a slowly evolving discussion on jackit-devel to try and decide
> what to do about it.
> --p

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