[unios] Re: Priorities

[Pieter Dumon]

From: Pieter Dumon <Pieter.Dumon@rug.ac.be>

> > I also think Beholder said a good thing... it *would* be harder to make the
> > OS less dependant on a specific hardware when designing for speed. If
> > machine specific optimizations is all that you require, then fine. But just
> > that doesn't give speed the right of the 2nd priority place. Optimizations
> > are really not as important as having a secure, flexible and well designed
> > system, are they?

No of course not. But it's not mainly code optimisation that makes an OS
fast. This can indeed be done later, but it's the overall design. And for
me, speed has still the second priority after stability. Securing a system
is something that can be implemented at a high level in the OS. (Well,
that depends on the architecture, off course).
 
> Yep I agree... I just think we're on the wrong track by saying that speed and
> flexibility are contrary concepts.  I think speed and flexibility are just
> contrary to memory requirements.  We may need more memory to achieve what we want,
> then if we optimized programs exactly for the hardware.  Although I don't rule out
> this system yet, I just don't have any ideas on making it flexible.

I dont agree on the " memory size ~ 1/features" statement.
I think we should really look at QNX. It's extremely stable,flexible,
fast and small (and secure off course). I don't say we have to take over
it's design, no, far from that, but QNX makes it clear that it's possible
and even easy to make a system stable,lexible and fast just by design.
Speed in QNX is not something that is added later, no, it is inherited
from the core design. 
QNX makes me think about using a second-generation microkernel (which is
by definition stable, flexible, secure,fast and small). What you run on
top of that microkernel, is not important when it comes to the design of 
that kernel. We could even make the kernel swappable. You really don't
have to use the client-server ideas that lay on the base of microkernel
design. 
We can think about a totaly different concept too, off course. Something
wich doesn't use a kernel or something. E.g. a system which only provides 
some generic interface to the hardware and in which memory manager
objects, task switching objects etc can be plugged/unplugged at runtime.

Pieter

----------------------------------------
 Pieter.Dumon@rug.ac.be               
                                      
 http://studwww.rug.ac.be/~pdumon     
 
 ICQ  : 12428974
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