Subject: Re: Real time scheduling in the kernel
To: Brett Lymn <>
From: Charles M. Hannum <mycroft@MIT.EDU>
List: tech-kern
Date: 03/15/1996 00:29:10
	   I have a mate that is wanting to know if there is any support for
   real time processes in the kernel - that is a process that, once
   started, is guarenteed to run to completion without interruption.  My
   mate says that he was talking with a guy who was hacking on the kernel
   before 4.2bsd came out and this guy was saying that putting the
   support in was no big deal.

The level of difficulty depends on what, precisely, you man by `real
time'.  There's a wide range, from simply changing the scheduler to
prefer `real time' processes, to pre-empting device drivers that are
acting on behalf of another process.

Obviously, at the low end, this is easy (if not trivial) to implement.
For practical `real time' applications, though, this is not very

   I suspect that, from what I have seen, that this support is not there.
   Am I correct on this?

There is currently no `real time' support in the NetBSD kernel.

   If I am, is there anyone with this on a "to do"

Not that I know of.