Re: [linux-audio-dev] an open letter to Linus re: low latency

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Subject: Re: [linux-audio-dev] an open letter to Linus re: low latency
From: Stefan Westerfeld (stefan_AT_space.twc.de)
Date: Sat Jun 24 2000 - 19:24:35 EEST


   Hi!

On Sat, Jun 24, 2000 at 06:47:07PM +0200, Benno Senoner wrote:
> On Thu, 22 Jun 2000, Stefan Westerfeld wrote:
> > >
> > > example: why is it that enlightenment has to develop its own sound
> > > server? kinda strange part of window manager...
> >
> > I think you can't blame anyone who is working on open source software (like
> > Linus does) for not being interested in your-favourite-feature. People are
> > developing the things they are good in and they are interested in. Everything
> > else (developing things you are not good in or not interested in) wouldn't
> > exactly help the software quality. ;)
> >
> > So the *most important* thing which is required to have sound mixing support
> > or low latency or whatever in the kernel is somebody who really cares about
> > it, who likes working on it and who is good at it.
> >
> > I personally tend to think that having too much sound stuff in the kernel
> > isn't a good idea either. We also do not run X11 in the kernel ;-). You have
> > some restrictions when writing kernel code, which you don't have when you're
> > able to solve the same thing in user land. Thats why I am working on aRts,
> > which can do the sound server thing esd does, too, but does a whole lot more
> > and may be just the solid multimedia foundation you ask for.
>
> Sorry Stefan, but I NEVER said the kernel should contain fancy "multimedia"
> support within the kernel space (perhaps in form of loadable modules etc,
> just like NT does with their GFX drivers and WDM drivers).
>
> I am for putting in userspace as much stuff as possible,
> and see the kernel as a mere process scheduler and IO device / VM abstraction
> API.
>
> Your arts soundserver (and all other audio software too) will suck BADLY on
> stanbdard linux, no matter how you implemented it.

Oh well, I think my reply was misunderstandable... it wasn't at all meant
to criticize the idea that linux should have extremely low latency. I just
wanted to underline the point that low latency scheduling is the only missing
feature we need in the kernel.

The original thought I was replying to was this:

] - music&sound, games, graphics etc. IMO the good multimedia foundation
] (both at the dirvers level and user-space libs) is more important to
] acceptance of linux as desktop than desktop environment/apps itself
] (gnome/kde etc.). more important in a sense that it should be developed
] first and desktop apps should build upon it rather than each develop its
] own foundation.

So my opinion is this:

- multimedia foundation is the right idea, should be done in user space,
  and can for instance be done by aRts (as always with open source, you are
  free to use it, help with it or write your own ;)

  just in case you wonder: aRts is in not kde dependant

- I fully support any effort to make the kernel suck less with scheduling -
  even if I had acceptable results with some tasks, I also see that other
  stuff, especially IDE makes aRts (and any other multimedia software) suck
  badly under linux. Especially if you're compiling or so in the background,
  you *will* get dropouts.

So yes, I suffer under the linux performace as everybody here, and I am really
glad that people like you are putting solid work into getting this fixed (e.g.
"real measurements" as compared to "ear tests").

I'll continue putting solid work in a framework, and in the end, I hope that
the outcome of the parallel effort is that we have a great userspace framework
which runs on a rock-stable-lowlatency-scheduling, and everybody will be happy.

   Cu... Stefan

-- 
  -* Stefan Westerfeld, stefan_AT_space.twc.de (PGP!), Hamburg/Germany
     KDE Developer, project infos at http://space.twc.de/~stefan/kde *-         


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