[rescue] Big SGIs at Home

[Francisco Javier Mesa-Martinez]

> It came from SGI that way :)  I havnt peeked under the hood, except to
> remove the single dual dual IP25 to use in the onyx, thereby leaving me
> with 32 processors.  It has 4 fully populated MC3 boards.  Interesting
> about the 18+ processors, how much performance decrease/processor did
> you see ??
> --

It was rather significant, I do not have the numbers with me. But
basically the lesson we learned was that we rather have more memory with
higher degree of interleaving than more than 20 something processors. The
R10K's in the XL only come with 2MB of cache (we were lucky we had the
IP's with 2MB per R10K not hte 1MB which used to be the norm), which is
pretty small since all of the processors are sniffing the same bus, and
1.2GB is not that much once you divide it by 32+ processors :) (you end up
with 35MBps per processor, which again is not that much... since we are
assuming peak numbers anyway :) ). I have to go down and check on the machine,
it has been shut down for so long, since it is not cost effective for the
power it consumes to the power it delivers... how times change, eh?