[linux-audio-user] low latency 2.4 help - needed

[Jorge Salgueiro]

yes, I use unstable + agnula demudi repositorie, and until now works
okey..., the demudi repositorie is a debian repositorie with just the
audio aplications.


On Sun, 06 Mar 2005 18:37:20 +0100, Atte André Jensen
<atte.jensen at gmail.com> wrote:
> Jack O'Quin wrote:
> 
> > "Best" depends on your needs and priorities.
> 
> I would accept a kernel that is only used for music. Actually the only
> thing I need realtime for is running csound5 in realtime controlled over
> midi. I just upgraded from csound4 and performance is better in csound5,
> but still I cannot get buffersize lower than 512 (csound-alone-latency:
> 12ms =  too much) without a click every 30 secs or so. csound4 clicked
> much more, about every 2 secs, so I'm thinking I'm close, mainly due to
> the fact csound5 is able to use the alsa drivers instead of oss-emulation.
> 
> To be honest I'm not sure exactly what is the cause of the problem
> (which is why I want to see what an optimized kernel will do), I can
> think of:
> 
> 1) kernel.
> 
> 2) unnecessary services
> 
> 3) the fact that my soundcard is usb (Edirol UA-1A)
> 
> 4) csound itself (doubt it)
> 
> 5) computer. Hope not, it a P4 2.4Ghz laptop
> 
> > For lowest latency, 2.6.10 with Ingo Molnar's realtime preemption
> > patches is currently the best.
> 
> That's new for me... You're not talking about this, right?
> 
> [atte at aarhus src]$ head linux-2.6.10-rt2.patch
> diff -ruN -X /home/joq/bin/kdiff.exclude
> linux-2.6.10-rc2-mm3/Documentation/realtime-lsm.txt
> linux-2.6.10-rc2-mm3-rt2/Documentation/realtime-lsm.txt
> --- linux-2.6.10-rc2-mm3/Documentation/realtime-lsm.txt Wed Dec 31
> 18:00:00 1969
> +++ linux-2.6.10-rc2-mm3-rt2/Documentation/realtime-lsm.txt     Wed Nov
> 24 09:58:29 2004
> @@ -0,0 +1,39 @@
> +
> +                   Realtime Linux Security Module
> +
> +
> +This Linux Security Module (LSM) enables realtime capabilities.  It
> +was written by Torben Hohn and Jack O'Quin, under the provisions of
> 
> I tried applying the above patch, but I didn't see anything new under
> "security" in the kernel config, so I guess I did something wrong...
> 
> Where to get the patches you're talking about, and what to do?
> 
> >  But, that requires considerable effort
> > on your part.
> 
> Not that much, since I'm on a home brewn 2.6.9... This also means that I
> have a working alsa setup. If i wen't with 2.4 I would have to install
> alsa seperately, so...
> 
> > A recent, stable 2.6.x kernel is also an easy option.  I'm getting as
> > good or better LL results with vanilla 2.6.10 than with 2.4.19 and the
> > LL patches.  I have not tried 2.6.11 yet, but expect it to be even
> > better.  IMO, latency is no longer a reason to avoid 2.6 kernels.
> 
> As mentioned, I'm already on 2.6.9.
> 
> > For the easiest solution, go with PlanetCCRMA (Fedora/RedHat) or
> > AGNULA/DeMuDi (Debian).  They've got this stuff all integrated and
> > readily available for binary download.
> 
> I'm not interrested in "easy" but in "best". I'm on debian/unstable, so
> maybe agnula would be possible. I just want to make sure that my current
> system is not "infected" with all kinds of agnula stuff. Is it possible
> just to get the low-latency kernel and use on an unstable system?
> 
> --
> peace, love & harmony
> Atte
> 
> http://www.atte.dk
> 
>