Re: AMIGA will use Linux, but Linux has several "multimedia-deficiencies"

Alexander Viro (viro@math.psu.edu)
Sat, 10 Jul 1999 10:49:55 -0400 (EDT)


On Sat, 10 Jul 1999, Benno Senoner wrote:

> Hello,
>
> I've just read that the next generation AMIGA will use Linux as the core OS,
> instead of QNX. ( http://www.amiga.com/diary/executive/linux-e.html )

What? They need an RT kernel, not a timesharing one.

> Amiga is a multimedia platform, and therefore needs realtime capatibilites.

Sure.

> Unfortunately actually Linux doesn't allow to play any realtime
> (low-latency) mulimedia content (audio/video,etc.) in a reliable fashion
> , during high system load, especially disk I/O.

Which doesn't mix well with timesharing.

> Actually there seems not a big interest to cure these deficiencies, just
> because many see Linux as a server OS , and not a desktop OS,
> on a web-server or fileserver you don't need guaranteed timing.
> (Or is there already some unoffical work underway to cure the scheduling
> problems of Linux ?)
>
> Who cares if his webpage shows up 150ms earlier or later ? ,
> or if your netscape executable which comes from the NFS server, is loaded
> 150ms later ? No one, I think.
>
> Does anyone know if the disk device driver (or device drivers in general) can be
> preempted from regular processes or is there no way to do this on Linux.

Lots of overhead for no good reason. If you need a RT - take a RT kernel
and don't mess with TS ones.

> Do we really need a microkernel to handle realtime multimedia ?
>
> Hopefully Amiga Inc, will help us to optimize these Linux deficiencies,
> through collaborating with the kernel/audio/video developement folks.
>
> comments ?

It's not a bug, it's a feature. "Optimize" will mean "screw normal usage".
Optimizing for RT != optimizing for TS. Ditto the other way round. They
should take RT-Linux or QNX, if they want RT. <looking at their page>
Oh, dear... Looks like marketdroids decided that popularity of Linux means
that they should use it and to hell with technical arguments. And managed
to convince PHBs. Paint me cynical, but... Methink they are in for a big
screwup.

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