Dual Core Or Dual CPU - What's the real difference in performance?

[Garrett Cooper]

Andrew Hammond wrote:
> On 2/7/07, Nicole Harrington <drumslayer2 at yahoo.com> wrote:
>>  Hello all,
>>  I have been building/using servers that were dual CPU
>> AMD Opteron systems for some time.  (usually 246
>> Opteron cpu's)
>>
>>  Now of course the world is shifting to Dual Core.
>>
>> Using FreeBSD, what is really the difference, besides
>> power and ability to shove in more memory, between
>> having the two seperate CPUS's?
> 
> Well, you also have two additional HT buses for memory access. And one
> additional HT bus for peripheral access although most motherboard
> manufacturers don't actually do anything with it.
> 
>>  What if I did 2, Dual Core cpu's? Would the SMP
>> overhead and sharing to a [Giant Locked] disk and or
>> network erase any benefits?
> 
> Benefits to what? Your computer can idle quite effectively with a 386
> processor while consuming less power, producing less heat and
> requiring much less capital outlay than any Opteron box.

I'm not sure where you got that info, but for the Pentium processor line 
at least, you're MUCH better off getting a Core Duo compared to the 
Pentium 4 HT enabled equivalent.

Intel's power system (at least at the hardware level) is pretty good 
about shutting down cores when not in use, and actually it's better 
power wise to get a dual core processor compared to a dual processor 
machine, since on a dual processor machine both processors are fired up 
at the same time.

Besides, with dual cores it's a shorter path electrically core to core, 
compared to a processor. The only OS that actually performs better with 
a dual single core processor setup compared to a single dual core 
processor would be Mac OSX (believe it or not). But that's because they 
use a mach kernel instead of a monolithic kernel like FreeBSD, Linux, 
and Windows.

Look up previous discussions on this list for the mach kernel and OSX if 
you're curious, or just look up the article on wikipedia.

-Garrett