Re: Difference between an RTOS and a OS like Linux ...

David A Rusling (rusling@linux.reo.dec.com)
Tue, 18 Feb 1997 10:20:48 +0000

>
> # Could somebody tell me the difference between an RTOS and a UN*X clone like
> # Linux .?
> # Why cant Linux be used to simulate an RTOS ? are there any .. ? What's the
> # important
> # thing about an RTOS? Can I get some help ... please ?
> #
> # vimalkumar.
>
> See the article in the February issue of "Linux Journal". The primary
> difference, as I understand it, is that the real-time software, which
> is collecting data or whatever, is guaranteed the resources it needs
> to operate in a timely, consistent manner. This is in contrast to the
> standard way in which the scheduler runs.
>
> Wil

However, Linux could be considered as a pretty good 'soft' real time
engine as opposed to hard (hey, the steam hammer's moving and you have
XXms to respond) real time. Linux does support two classes of real time
processes (see the scheduler for details) and POSIX real time compliance
would not be overly difficult. Also, there have been several experiments
bolting Linux onto the side of a hard real time exec which show that
Linux is pretty resiliant to not running for a while (whenever hard
real time stuff *has* to happen).

Dave

----------------------------------------------------------------------
David A Rusling Principal Engineer
European Semiconductor Applications Digital Equipment Co Ltd.,
Engineering PO Box 121,
Imperial Way,
Worton Grange
Reading RG2 0TU
Linux, Alpha, StrongArm, PCI Tel: UK-(0)1734-204380
Fax: UK-(0)1734-203133
----------------------------------------------------------------------