[rescue] SGI tidbits

[Francisco Javier Mesa-Martinez]

On Sat, 28 Sep 2002, Joshua D Boyd wrote:

> > I learned this when asking about how much I should boost the
> > O2's memory, since it only has 160MB.  Apparently the OS loads
> > itself up and pretty much stays there.  I guess they took a
> > dim view of swapping with IRIX.
> 
> I wonder...
> 
> Cray took an extremely dim view on swapping, to the extent that they
> didn't support it at all.  Now, wasn't the Irix 6.x line designed while
> Cray was owned by and influencing the highend design at SGI?

Nope, early Cray did not had virtual memory. Crays were Supercomputer, so
by definition they were supposed to be compute-bound not i/o-bound. The
way cray designed its machines was by looking at the slowest component and
building on top of it, since the performance of the machine would be
bound by it. So he decided that virtual memory would be way too slow of
a bottleneck as the slowest part of the machine... so they threw it out.
Crays were not ment to be general purpose machines, they were mostly used
as large math crunchers in batch environment. So general support for
multiprogramming natively in the HW did not make much sense either... I
guess that is what the front end machines were for.

Irix on the other hand has had vm almost from the begining...and everyone
should take swaping with a grim view no matter what OS they end up using,
since it is going to become the bottleneck of your job. I do not know why
he/she was trying to make it an Irix-centric issue. Byt design/performance
Irix is one of the best unices out there...

Cray did not had much influence in SGI's modern machines, they just used
the name as a marketing ploy (i.e. cray-link had no cray design parts at
all). Much like Tera did once the bought Cray, the figured out the name
had a lot of value so they ended up renamig the whole company... since
they figured out that the market for their MTA machines was almost non
existant.