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32 bit vs 64 bit
This thread belongs to expert.forumgeeks.net


2009-07-13 07:20 GMT   |   #1
 
What does 32 bit Suse do on a 64 bit processor? Does is use both cores
in 32 bit mode or does it only use half the processor?
If it uses both core, at the same time? or one then the other.
2009-07-13 07:20 GMT   |   #2
 
The full 64 bit address can't be used in 32 bit linux. Although I
wonder what would happen if the kernel was recompiled on the running
linux machine in 64 bit mode, which gcc should be able to do.
2009-07-13 08:30 GMT   |   #3
 
The default kernel is now SMP which means all processors are used, it
does not matter 32bit or 64bit, 32 bit runs fine on a 64 bit machine.

Install xosview and it will graphically show CPU/Memory/... etc usage.
2009-07-13 09:20 GMT   |   #4
 
It uses both cores just fine.
2009-07-13 11:20 GMT   |   #5
 
However, it can only use up to 4GB of memory.
2009-07-13 11:20 GMT   |   #6
 
I was about to write that, too.
But I din't since it was not asked.

I'm glad that I din't reply the way I first thought (about half the
processor and stuff...)
2009-07-13 13:20 GMT   |   #7
 
I wanted to elaborate on dualbooting and trying it out yourself. I
didn't. Very Happy
2009-07-13 13:20 GMT   |   #8
 
houghi wrote:
However, it can only use up to 4GB of memory.

Not true or at least very inaccurate - see PAE.
2009-07-13 14:42 GMT   |   #9
 
yeah. PAE is like artificial limb - you can use it, its much better
than nothing, but its still far more inferior than real one.
Unless you are using 32-bit only processor (like old xeons or
pentiums) - avoid PAE- its slower than 'real' 64bit, also one thread
can use no more than 3.5 (3.6?) gb of memory, also PaX /if you are
using it/ doesnt work fine (i.e. it works, but you pay its price with
speed of system) on PAE'd system.
2009-07-14 03:20 GMT   |   #10
 
piscesboy wrote:
The full 64 bit address can't be used in 32 bit linux. Although I
wonder what would happen if the kernel was recompiled on the running
linux machine in 64 bit mode, which gcc should be able to do.

THAT, and recompiling all (packaged) applications so that THEY too can
use large addresses, has already been done in the x86_64 version of
openSUSE.
Of course that makes both kernel and applications larger (64-bits
address pointers etc) so only use the x86_64 version when you got the
RAM for it, there's not much use for it in a 1 or even 3 GB machine,
32-bit will do just fine on those PC's.

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