[LAU] Realtime Kernel

[Mark Knecht]

There is really no reason that I know of that you cannot build this
kernel yourself. It's not horribly difficult once you've done it a few
times. It can be quite daunting when you're up to bat for the first
time though. the trick is understanding what driver modules you are
using and making sure all of those are included in the configuration
of your new kernel. Once you get past that step it's just a matter of
adding a new option in the grub config file and trying it out.

>From the RTWiki these are the commands to download and patch a kernel:


# wget ftp://ftp.kernel.org/pub/linux/kernel/v2.6/linux-2.6.23.1.tar.bz2
# wget http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.23.1-rt11.bz2
# tar xfj linux-2.6.23.1.tar.bz2
# cd linux-2.6.23.1
# bzcat2 ../patch-2.6.23.1-rt11.bz2 | patch -p1

The above is for 2.6.23. If you were going to do it you might as well
go for 2.6.24.

Changing the kernel itself should not cause any changes in the
stability of your applications. They really exist at a higher level
and just talk to the kernel underneath it. If a new minor revision
kernel upgrade breaks an application I think it would generally be
considered a regression in the kernel and would get fixed. I have
kernels ranging back to 2.6.14. they all work.

Hope this helps,
Mark

On Tue, Mar 18, 2008 at 12:41 PM, Arda Eden <ardaeden at gmail.com> wrote:
> I'm a PARDUS (a Turkish GNU/Linux distro) user so that the latest kernel
> provided by my distro developers is 2.6.18.8-86. I can't know why they don't
> complile a new one but i think that it's about the stability of most
> applications provided by thet distro.
>
> Which distro of Linux is most suitable for most linux audio applications ?
>
>
>
> On Tue, Mar 18, 2008 at 9:36 PM, Mark Knecht <markknecht at gmail.com> wrote:
>
> > That kernel is getting pretty old. I'm running 2.6.24-rt1 here. you
> > might want to check out the RT-Wiki or some of the sites for using RT
> > kernels with audio apps.
> >
> >
> > http://rt.wiki.kernel.org/index.php/Main_Page
> >
> > The above link gives instructions for patching a kernel to get to an RT
> kernel.
> >
> > Hope this helps,
> > Mark
> >
> >
> >
> >
> > On Tue, Mar 18, 2008 at 12:02 PM, Arda Eden <ardaeden at gmail.com> wrote:
> > > Hmm,
> > > So this is all about my kernel:
> > > Linux melinda 2.6.18.8-86 #2 SMP Mon Feb 11 00:50:59 EET 2008 i686
> mobile
> > > AMD Athlon(tm) XP-M 2200+ GNU/Linux
> > >
> > > Is it possible to patch it in order to make it a RT kernel ?
> > >
> > >
> > > On Tue, Mar 18, 2008 at 8:59 PM, Mark Knecht <markknecht at gmail.com>
> wrote:
> > > >
> > > > On Tue, Mar 18, 2008 at 11:41 AM, Arda Eden <ardaeden at gmail.com>
> wrote:
> > > > > So what does a realtime kernel change ? Makes my latency 1 ms ?
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > On Tue, Mar 18, 2008 at 8:38 PM, Arnold Krille
> <arnold at arnoldarts.de>
> > > wrote:
> > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > Am Dienstag, 18. März 2008 schrieb Mark Knecht:
> > > > > >
> > > > > > > On Tue, Mar 18, 2008 at 11:25 AM, Arda Eden <ardaeden at gmail.com>
> > > wrote:
> > > > > > > > So is it really necessary to have a realtime kernel in order
> to
> > > use
> > > > > linux
> > > > > > > > audio applications without any latencies or xruns ?
> > > > > > > It is not possible to use ANY kernel with NO latencies. EVERY
> kernel
> > > > > > > has latencies. The question is how low do you want the latencies
> to
> > > > > > > be? If you can exist with 50mS or higher you might get away with
> a
> > > > > > > standard kernel. If you want to run with 1.2mS latency then you
> will
> > > > > > > absolutely have to have a real-time enabled kernel.
> > > > > >
> > > > > > Still it has to be noted that you can achieve 5ms latency without
> a
> > > > > > RT-kernel... Even with an el-cheapo builtin soundcard...
> > > > > >
> > > > > > Arnold
> > > >
> > > > Absolutely. The most recent kernels are often quite good. However I
> > > > would say that the difference between a standard kernel running 5mS
> > > > and a RT kernel running 5mS is that the RT kernel is far more likely
> > > > to meet the 5mS requirement under heavy system loads while the
> > > > standard kernel may, at times, give a bit too much time to non-rt
> > > > threads and not get back to your audio thread as fast as someone might
> > > > want.
> > > >
> > > > If you want the highest reliability means of meeting your RT
> > > > requirements all the time then use the RT kernel. If you are just
> > > > doing home recording and can accept an occasional xrun (i.e. - a
> > > > glitch in the recorded data) then stick with the standard kernel for
> > > > as long as it works for you.
> > > >
> > > > Just my view,
> > > > Mark
> > > >
> > >
> > >
> > >
> > > --
> > > Arda EDEN
> > > Cumhuriyet University
> > > Faculty of Fine Arts
> > > Department of Music Technology
> > > Sivas/TURKEY
> >
>
>
>
> --
>
> Arda EDEN
> Cumhuriyet University
> Faculty of Fine Arts
> Department of Music Technology
> Sivas/TURKEY