Re: What about...

[ralf@uni-koblenz.de]

On Fri, Jul 17, 1998 at 11:19:54AM -0700, William J. Earl wrote:

>      I expect that much of the work will gradually happen in linux, once
> the remaining small-CPU-count issues are resolved.  Right now, there
> is no shortage of interesting problems to attack.  :-)

Actually I'd hate it if Linux'd be ``finished'' ...

>      One possible way to approach the large-CPU-count space with linux
> is to indeed run multiple linux kernels, one per node in a ccNUMA
> machine, and add a distributed OS layer at a fairly high level.  If it
> is not underway already somewhere, I would expect someone to take up
> the project as a graduate school project.  Some systems of this sort
> have been built or attempted, with varying degrees of success.  Given
> the linux bias toward small and simple, a linux-based distributed OS
> might actually work.

I don't know the exact technical details but something similar has already
been done back in '95 (?) when some guys in Australia ported Linux to
Fujitsu's AP1000.  That's of course a different architecture and a
multikernel approach makes much more sense there.

>      One important ingredient in such a system, which would be
> valuable immediately for clusters, would be a efficient distributed
> volume manager and file system.  

Hans Reiser is currently working on a new filesystem with alot of fresh
ideas.  In some aspects what he is aiming at is similar to XFS, in some
aspects not.  He basically started on a white sheet of paper with his design,
so his team's code isn't contaminated by old ideas.  His work looks pretty
promising.  Among his plans is also the implementation of a distributed
filesystem.  Current benchmarks are looking pretty good, in fact in
some cases extremly good.  The URL to checkout for interested people is
http://idiom.com/~beverly/reiserfs.html.

>      In any case, trying to port linux straight to a large ccNUMA 
> (or even a large SMP) system would be a lot of effort for limited
> return at present.

Explecitly not talking about the MIPS port - I think it makes sense in
working on porting to machines beyond what we currently scale to.  But
I agree about the ``large'' thing.

  Ralf