RTCoreBSD

[Norbert Koch]

> > > Hi,
> > > 
> > > I found this real-time OS based on BSD:
> > >
> >
> http://www.sdcsystems.com/realtime-linux.htm#rtcorebsd
> > > 
> > > I m wondering what technology they used to make
> > > FreeBSD as a real-time OS. I thought kqueue/kevent
> > is
> > > a key component? any comment?
> > > 
> > > Thanks
> > > Sam
> > 
> > I think it's just that *old* rtlinux concept of
> > having a hard real time kernel and running the
> > operating system as some kind of an idle task
> > above that. As far as I remember FSMLabs earlier
> > press information talked about using NetBSD for
> > that.
> > 
> Does current version of FreeBSD uses real-time
> scheduler at the kernel? If it does, which part of the
> code (in /usr/src) contains those code?

Depends on what you mean.
FreeBSD is no rtos, but has rtprio(1).
It allows to have fixed process priorities
in contrast to the usual 'varying' unix priorites.
But it is still possible for a high priority process
to be blocked by a lower priority process entering a
system call for a non-deterministic amount of time.
This is at least so for 4.X, but may be less true
for 6.X whith the kernel becoming more and more
preemptable.

Norbert