[Beowulf] Win64 Clusters!!!!!!!!!!!!

Jon Forrest jlforrest at berkeley.edu
Sun Apr 8 17:29:27 PDT 2007

Mark Hahn wrote:
>> add the additional difficulty of getting 64-bit drivers
> for windows, at least.  64b-ness was never much of an issue for linux.

The title of the message I was responding to was
about Win64, but your point is valid. Switching
to 64-bits is much easier in the Linux world than
the WinXX world.

> I think you underestimate the number of jobs that can effectively
> use more than 2GB/proc, and which can make excellent use of having
> twice as many registers.  not to mention the fact that the kernel likes 
> having a big-flat address space, even if procs get by with 32b.

I made no claims about the number of apps that need more address
space than they get in the 32-bit world, only that additional
address space is the only reason for making the switch.
I admittedly don't have references at hand about my claim
about the advantages of the additional registers being reduced
by the increased number of bits. This came up several years ago
when x86-64 was first coming out. If somebody has newer data
I'll be the first to retract my claim. I think it makes intuitive
sense, though.

> 32b procs run rather well on 64b systems - you get small pointers
> and you don't get those annoying extra registers.  just compile -m32.

Again, I agree that on Linux this is true, but in a Win64 cluster
the additional difficulties of switching to 64-bits make this
more of a problem.

> I've heard it said that some DB's have surprisingly large text.

I worked as a SQLServer developer at Sybase, and in the Postgres
research group at UCB and I never noticed this. Maybe things have
changed since then. The one area where I've heard text gets quite
large is in CAD simulations, but much of the code isn't human

For yuks, I recently added up the text size of *every* executable
program and library I found on my Fedora Core 6 system. I did
not do a very good job at weeding out the dups caused by
symbolic links and the like, but the sum total of *all* these
text segments would have easily fit in a 32-bit address space.

Jon Forrest
Unix Computing Support
College of Chemistry
173 Tan Hall
University of California Berkeley
Berkeley, CA
jlforrest at berkeley.edu

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