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

Jon Forrest jlforrest at berkeley.edu
Fri Apr 6 16:57:18 PDT 2007

One thing I've noticed about 64-bit computing in general
is that it's being oversold. The **only** reason
for running in 64-bit mode is if you need the additional
address space. Indeed, for some apps this is critical and
64-bit computing solves a real problem. For apps that
don't need the extra address space, the benefits of
the additional registers in x86-64 are nearly undone
by the need to move more bits around, so 32-bit
and 64-bit modes are pretty much a push. When you
add the additional difficulty of getting 64-bit drivers
and what-not, I don't think it's worth messing with 64-bit
computing for apps that don't need the address space.

One additional way 64-bit computing is being oversold
is that there aren't now, and maybe never will be, any
human written program that requires more than 32 bits
for the instruction segment of the program. It's simply
too complex for a human, or a group of humans, to write
this much code. Again, note that this says nothing
about the data segment of a program. Also, people tell
me that there are programs that were generated by other
programs that are larger than 32 bits. I've never seen
one, but maybe they exist, and that's what I'm talking
about human written programs.

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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