[wplug] (OT) 32 more bits

Carl Benedict cbenedic at pittsburghtechs.com
Tue Apr 26 18:39:30 EDT 2005


On Tue, 2005-04-26 at 17:54 -0400, Brandon Kuczenski wrote:
> What with Microsoft's announcement of plans to release "three new 
> versions" of Windows that run on 64-bit architecture, it's been all over 
> the news lately.  Of course, 64-bit Linux has been around for awhile (it's 
> been, what, a year since AMD first released an Athlon 64?).
> 
> Meanwhile, most of us who have personal or otherwise light-duty servers 
> are probably getting by just fine with 3, 5, 10 year old equipment. 
> Obviously industrial servers have it a little more tough, but I'm not 
> mistaken when I say 1 64-bit machine != 2 32-bit machines, right?  I just 
> don't see what's the big deal.
> 
> I'm not too well-versed in a lot of hardware issues, so I would like to 
> hear what more knowledgable people (you) think about 64-bit architecture. 
> What bottlenecks does it remove?  What are its primary benefits? 
> Compared to CPU speed? How much of a performance increase would someone 
> see on an otherwise identical high-end system (say, 2-3 GHz) that runs a 
> 32 vs. a 64 bit CPU?  On servers? on desktops?  in toasters?
> 
> etc.
> 

AFAIK, it doesn't solve any x86 design issues.  What it does solve is
effectively doubling the maximum size of on-die registers (i.e. EAX,
EBX, ECX, EDX, ESP, et al).  This will allow 64 bits of information to
be stored in each register, versus the 32 bits on current chips like
AthlonXP.  The biggest problem is/was lack of software available to take
advantage of these registers.  I have not read too much about the 64 bit
architecture, but I would assume this will work much like the transition
from 16bit to 32bit.  Old applications (in this case, 32bit) could still
access the 'old' 32bit registers (EAX, EBX, etc), and therefore run as
they did before with no performance gain.  Meanwhile, the 'new' 64bit
apps would use the 64bit registers.  

>From a performance standpoint, you are moving twice as much data in the
same amount of time.  This would reduce the amount of times you would
access other subsystems (RAM, HDD, etc).  

There may be more additional registers and functions implemented in the
64bit architecture that I'm unaware of.  My comparison is based solely
on expanding the existing 32bit registers.  

-- 
Carl Benedict
Pittsburgh Techs
Main:  724-741-0233
http://www.pittsburghtechs.com
cbenedic at pittsburghtechs.com



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