Subject: Re: Hard realtime scheduling
To: None <>
From: Joerg Sonnenberger <>
List: tech-kern
Date: 04/04/2005 15:25:20
On Mon, Apr 04, 2005 at 12:02:07PM +0200, Hubert Feyrer wrote:
> On Mon, 4 Apr 2005, Oliver Korpilla wrote:
> >As I've read support for realtime scheduling is on the agenda since the 
> >2004 Annual Meeting, so is anyone actively working on this? May I help out 
> >in any way? What approach are you using, where can I read up on it 
> >(papers, articles, etc.)? Is there consensus about the topic?
> I don't know about any details in NetBSD, but the way to go is probably to 
> make the kernel preemptive as first step. This will also (hugely) benefit 
> SMP performance (i.e. no more biglock).

Making the kernel preemption and supporting hard RT are not the same thing
at all. They are not even similiar. E.g. you can do hard RT in a coroutine
like kernel setting without having any preemption at all.

It is important which functions can be used by the RT core and it is often
easier to program RT save functions if you don't have to deal with

The easiest way for Linux RT extension like support is just extending
the current IPL model, which is almost what Linux RT parts do too.