The different realtime kernels

[Scott Lavender]

On Fri, Oct 1, 2010 at 7:38 AM, Ralf Mardorf <ralf.mardorf at alice-dsl.net>wrote:

> On Thu, 2010-09-30 at 14:10 -0500, Scott Lavender wrote:
>
> > [snip]
> > This is not a rhetorical question.  I, as Ubuntu Studio project lead,
> > would like to include it.  If you can provide a tenable method to
> > include the -rt kernel in the Ubuntu Studio ISO image I would like to
> > implement it.
> > [snip]
>
> Hi Scott :)
>
> I'm not sure, if I do understand the problem.
>
> Does Ubuntu need the same vanilla kernel version for different kind of
> kernels, e.g. to provide packages for proprietary graphic modules?
> If so, IMO it's not needed to make the multimedia distro full compatible
> with a regular Ubuntu.
>
> * snip *

I think you are missing the point.

It does not matter _why_ certain kernels are maintained and available in the
repositories.  It only matters _that_ the decision was made.

The only kernels I can include within a Ubuntu Studio ISO image are the
kernels available from the official Ubuntu archives.

Furthermore, I do not decide which kernels may be included in the archives.
That ultimate decision is made by others, although I may provide some small
influence on it.  This is an example of when I mentioned "working within the
Ubuntu framework".

To summarize:  Others control which kernels are available and maintained in
the archives and I get to select from the available kernels which one to
include in the Ubuntu Studio ISO image.

To state what is "needed" or "required" or "worthless without" for
multimedia production is irrelevant.  I say again, to build a Ubuntu Studio
ISO image within the Ubuntu framework I must choose from the available
kernels in the repositories, of which I wield extremely limited influence in
deciding which are to be available.



> Multimedia producer just need a kernel-rt and a package including the
> headers to compile e.g. drivers for graphics.
>
> For my needs the kernel-rt doesn't provide hard enough real-time, but
> the kernel-rt is a compromise that might enable some audio productions.
>
> You might wish to compare a C64, Atari ST or stand alone sequencer from
> the eighties with a kernel-rt and a kernel without rt-patch used by a
> good classical or jazz musician. There still is too much jitter, but the
> kernel-rt for sure will be the first kernel, that might be able to get
> the knack of it.
>
> The kernel-rt is the best we do have for Linux, hence it's invalid to
> use a less good kernel, as long as even the kernel-rt isn't able to do
> hard real-time.
>
> So, if there should be a rule for Ubuntu, that all patched kernels has
> to base on the same vanilla version, which is a good thought, it's not
> good for multimedia productions.
>

> There are coders who program the rt-patch, to make Linux better and
> better, it's not smart if a multimedia distro tries to be smarter by not
> using a kernel-rt, because it shouldn't be needed.
>
> The kernel-rt is needed and there should be no rule not to use it.
>
> Btw. to make the issue harder. It's not only that there isn't a rt-patch
> for every vanilla kernel, sometimes a current
> rt-patch-kernel-combination can be bad, so that we need to keep older
> rt-patched kernels. Sometimes it's not possible to keep 'things' that
> are available by a generic kernel of the same vanilla version, when
> using the rt-patch, but there's no need to keep all kernel features for
> real-time audio productions.
>
>
* snip *

No one is suggesting that the -rt kernel is not a good thing or that is not
to be preferred over other kernels.  However, stating that the -rt kernel is
needed or multimedia production is worthless without it is not going to
change the fact that the -rt kernel will not be included in an Ubuntu Studio
ISO image for the reasons stated above.

Furthermore, no one is stating that you should not use the -rt kernel.
Quite the contrary, it is almost required for laptop users with firewire
audio interfaces and we have made it very clear that we will make the -rt
kernel available via a PPA.

Again, this is not our choice to include a kernel other than the -rt kernel
released in Ubuntu Studio.  It is a necessity dictated by what is available
in the repositories.

Lastly, I am curious to which hardware you are using if you find that the
-rt kernel is not hard time enough for your needs.


The need for hard real-time is an exceptional case, not only for
> multimedia production, there are other real-time patches, e.g. for the
> Enhanced Machine Controller project.
> Some people and you might be fine with a non-real-time patched kernel,
> but most professional studios aren't even fine with the kernel-rt or on
> Windows  ASIO, resp. ASIO + Nuendo on some machines should be near to
> eighties hard real-time.
>

* snip *

I would argue that Ubuntu Studio is not for a professional studio.

Despite what others might argue or what various documentation might say, I
believe the Ubuntu Studio is NOT for professional use in a recording studio.

In my opinion, much greater control would be required to tailor kernels,
applications, and system systems.  A company like Indamixx and their OS,
Transmission 4.0, would be an example.
http://www.indamixx.com/indamixx-iso-download.html

To be direct, I would first remove Pulse Audio, stop shipping all graphical
and video applications, and use a lighter desktop to maximize performance
for starters.  Additional changes would be required as well, there were just
the first I could think of.

Before some ask why isn't this done already (especially removing Pulse
Audio), we lack the developer resources to handle it and most of our users
most likely use the same machine for normal day-to-day uses (i.e. internet,
email, etc).



> Cheers!
>
> Ralf
>
>
I hope you find this information useful.

Regards,
ScottL
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://lists.ubuntu.com/archives/ubuntu-studio-users/attachments/20101001/b8697785/attachment-0001.htm