[SciPy-user] 64 bit and 32 bit on Ubuntu

Anne Archibald peridot.faceted@gmail....
Mon Oct 13 10:25:15 CDT 2008


2008/10/12 Kurt Smith <kwmsmith@gmail.com>:

> I've recently acquired a new Ubuntu system, and unfortunately some 3rd
> party software I'd like to use won't work under the 64 bit version of
> the OS, yet.  It's not a deal breaker, however, and I'm willing to
> work around it as long as there are compelling reasons to use 64 bit
> for numerical work, specifically under scipy, etc.  I'm not well
> versed in the low-level pros and cons of 64 bit vs 32 bit, esp. as to
> how it affects scipy performance.  Can you enlighten me?  I"m on an
> Intel Core 2 Duo, 3.16 GHz, E8500, 4 GB RAM.  Will using 64 bit yield
> great benefits running scipy/numpy code automatically, or will it
> require fine-tuning on my part?  Will 64 bit yield benefits besides
> having a larger address space (besides the fact that my 4 GB RAM is
> still addressable by 32 bits, anyway)?

I think memory is the only major reason to prefer 64 bits. The speed
difference will probably be minimal. But having a 64-bit address space
means that if your applications get too big for RAM they just slow
down, as opposed to crashing and forcing you to rewrite them. You will
also find, I think, that running in 32-bit mode you cannot access the
last gigabyte or so of physical RAM. This can make a big difference
too.

Anne


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