x86 vs. x86_64

[Kurt Granroth]

Just to be pedantic; Matt is correct in his use of 'AND' with the 
memory.  It is 'have more than 4GB RAM *AND* something that can use more 
than 4GB in one process'.

Basically, this is due to PAE.  The PAE extension (which all modern CPUs 
support) allow the OS to access up to 64GB of memory, even on a 32-bit 
x86 system.  There's no need for a 64-bit processor for that.

HOWEVER, PAE doesn't permit a single process from mapping or allocating 
more than 4GB.  That's where you'll need 64-bit processors.

And if you don't know for sure that you need that capability... then you 
definitely don't.  It's very very rare (unless, of course, you are in 
the fields that do need that and then you'd know that).

On 3/25/10 5:38 PM, Stephen wrote:
> this is pretty accurate. if you are at the 4g limit or more then 64
> bit. or if you are doing some really high end memory intensive
> applications then you will have a need, otherwise 32 bit is the better
> idea for compatibility and ease of use (some weirdness with flash in
> 64 bit, solvable but you have some hoops to jump, there are a few
> others like this)
>
> On Thu, Mar 25, 2010 at 3:32 PM, Matt Graham<danceswithcrows at usa.net>  wrote:
>> From: Nathan England<nathan at paysonlinux.org>
>>> Before I spend any time downloading and trying it myself, has any one taken
>>> the time to compare performance differences in every day usage between
>>> ubuntu x86 and the 64 bit version?
>>
>> There is essentially ZERO performance difference between 64- and 32-bit Linux
>> for normal user apps AFAICT on a Gentoo box.  Couple that with the fact that
>> at least one app (epsxe, PSX emulator) doesn't work at all on 64-bit Linux,
>> and it's a no-brainer:  Use 32-bit.
>>
>> The only reason that I can see to use 64-bit Linux is if you have more than 4G
>> RAM in your box AND you've got something that can benefit from malloc()ing
>> more than 4G of RAM in one process.  So if you're running a big DB or a huge
>> numerical simulation or something like that, go 64-bit.  Otherwise, go
>> 32-bit.
>>
>> (Constructive criticism and flying attack porcupines welcomed, since the above
>> post may be full of bovine feces....)
>>
>> --
>> Matt G / Dances With Crows
>> The Crow202 Blog:  http://crow202.org/wordpress/
>> There is no Darkness in Eternity/But only Light too dim for us to see
>>
>>
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