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Date: Tue, 24 Mar 2009 13:26:35 +0100
From: "Giacomo A. Catenazzi" <cate-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>
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To: debian-devel-0aAXYlwwYIJuHlm7Suoebg@public.gmane.org
Subject: Re: realtime kernel for Debian
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Raphael Hertzog wrote:
> On Tue, 24 Mar 2009, Giacomo A. Catenazzi wrote:
>> Do you really need real time kernel?
>> Debian is a technical driven project, but reading the previous two quotes,
>> "real time" is used as marketing thing.
> 
> It's good to question the use of any feature, but a real-time kernel is
> certainly very useful in many industrial applications and Debian is
> popular in that field. (Don't put a marketing label on anything where
> you are not yourself sure of your expertise.)

Yes, I didn't write very well my sentence: the previous quotes was more
about "there exist rt kernels", "ubuntu has a rt kernel", but not solid
requirements. I had to write some "seems", and I'm sorry for the two
quoted people if it seems an attack.
Anyway, later in the mail, I asked for precise needs, so we could see
better what we should improve.

IMHO most users want a low latency kernel, but not a slower kernel, so
a CONFIG_HZ_1000 would be nice.  But the original post was about
multimedia production (and not reproduction), so the needs are probably
other.

My point was more:
- Debian has not rt kernel. Why? Non DD interested or/and low demand?
   This is an important point. We must not produce a rt-kernel if
   we cannot provide testers and developers (in unstable).
- kernel management is a weak point in distribution: no good method
   for kernel dependencies, using full capabilities, ...

so IMHO we should try harder with the normal kernel, so that we
can use the same infrastructure and testers. If we fail and we
are able to support rt kernels, IMO it is good to provide it in Debian.

The original mail was about "multimedia production" and few year ago kernel
developers had a lot of interaction with music industries.
I'm not an expert in the field, but how far are we in their need with
standard kernels?)


> I do use a real-time kernel on a Debian based system for one of my
> customers (but I have to recompile the kernel anyway because I do other
> customizations) and I have good reasons to do so because I can't suffer
> serial overrun and I must ensure that the serial interrupt handler
> is run in the required time and that no other (kernel) task has higher
> priority.

These *other customizations* are important to rt-kernel. So we need
a person (or more) that know the needs and could support us.
"realtime" alone is only a label ;-)

ciao
	cate


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