64-bit Kernel Question

[Patrick O'Callaghan]

On Mon, 2009-03-09 at 12:49 -0700, Adam Williamson wrote:
> On Mon, 2009-03-09 at 12:41 -0600, Petrus de Calguarium wrote:
> 
> > As memory requirements for 64-bit are anywhere from 50-100% greater and 
> > the only appreciable difference is a "psychological" performance boost, what 
> > REAL benefit is there, actually?
> 
> It's not psychological, it's just not noticeable in most regular
> operations. Actually, most people wouldn't notice if you replaced their
> CPU with one which was twice as fast (or, as the BOFH knows, half as
> fast...), most of the time, because very few of the operations most
> people do day-to-day are remotely CPU-bound. A few years ago I was
> running a 2.4GHz (Pentium 4-era) Celeron as my desktop. The CPU fan gave
> out, so the CPU throttled itself down to 800MHz and kept running. I
> didn't notice for a fortnight.
> 
> The most common CPU-bound operation in our world, I guess, is
> compilation, and you would notice a definite improvement in speed there,
> running x86-64 vs x86-32 - not huge, but noticeable. Certain database
> and I think scientific operations that are CPU-bound also derive a
> significant benefit. It depends on whether the code can take advantage
> of much bigger registers, AIUI.

Anyone who does even casual video processing (e.g. with transcode
filters) definitely will notice. This is something that pegs both cores
to 100% when I run it, until the fan kicks in and it slows a bit.

poc