[Live-demo] Introduction

Hamish hamish_b at yahoo.com
Mon Nov 22 20:13:03 PST 2010

Jonathan wrote:
> Particularly I would like to test in a 64 bit environment

Hi and welcome.

for what it's worth & as is my understanding, despite common
perceptions and advertising campaigns, 64bit is not magically
faster and better than 32bit. fundamentally it just means that
the addressable space goes from 2^32 bytes (a couple of gigs) to
2^64 (computer with that limit hasn't been invented yet).
Integers can count higher by using twice the number of bits to
store themselves in, and that's all.

So 64bit is great for dealing with huge geo-data files (LFS),
although most modern 32bit operating systems can deal with eg
>2gb files. WindowsXP famously doesn't reach it's theoretical
limit of 4gb RAM, and the program saving/reading the file has
to use the right variable type (eg off_t) in the memory address
to be 32bit LFS-capable as well.

actually if huge files/memory requirements are not an issue for
you, you might very well be better off sticking with 32-bit as
it only needs to push half of the I/O bandwidth!

On the other hand, while amd64 CPUs runs 32bit quite well, the
CPUs will, with time, be tuned for 64bit instruction sets.
..maybe the increased number of registers helps more than
anything else to unclog processing bottlenecks?

So, unless working with really massive datasets is a goal for
our demo DVD, I'm not entirely convinced that it gains us
anything useful, but it does make the dvd unusable on xx% of
the computers out there, and like it or not, 32 bit PCs will
be around for the next 5-7 years.



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