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

Mark Hahn hahn at mcmaster.ca
Sun Apr 8 10:28:39 PDT 2007

> add the additional difficulty of getting 64-bit drivers

for windows, at least.  64b-ness was never much of an issue for linux.

> and what-not, I don't think it's worth messing with 64-bit
> computing for apps that don't need the address space.

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.

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

but I'm curious whether you have some data to back up the assertion
that carrying around the extra bits is a significant cost.  are you
doing something involving lots of pointers (sparse matrices, perhaps
or something with graphs/trees)?

> 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

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

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