Dual Core or Quad Core?

[Jerry Feldman]

On Fri, 29 Jun 2007 09:53:05 -0400
Warren Luebkeman <warren at resara.com> wrote:

> I asked for a quote on a server yesterday from our hardware provider, and the 
> sales guy told me about a great new deal.  For the same price as a Dual Core, 
> 2 Ghz Xeon processor, I can get a Quad Core 1.6ghz Xeon processor.  My first 
> impression was four must be better than two, but is it really?
> 
> The server is supposed to be a 50 user Linux terminal server.  Our current 
> specs for this system are:
> 
> Dual Processor Dual Core (4 Processors)
> 6 GB Ram
> 15K SAS Hard Drives
> 
> So now I can build the same system, but with 8 processors vs. 4, for the same 
> price.  My thought is because its a terminal server, the speed of the 
> processors is less critical to the number of processors you have, because you 
> need to distribute the load of 50 users across one server.  I can't imagine a 
> word processor running at 1.6 Ghz vs. 2 Ghz should perform any differently.  
> So by moving to more processors, I should have less processes running on each 
> processor, which according to my very rudimentary logic suggests that the 
> performance should be better, or at least, more efficient.
> 
> What do you think?  Aside from the cool factor of having 8 processors, I would 
> like to make the RIGHT decision regarding what server I buy.  
> 
> I defer to the wisdom of the LUG to show me the way!

Most of the previous posts have pretty well answered most everything.
As Maddog points out, Linux scales well up to 8 CPUs, but much work is
being done with 32, 64, and 128 by IBM, HP, and SGI.  In your case,
it's not so much that you are going to stress the CPUs, it is more the
I/O of loading the applications. Fortunately, Linux and Unix
applications do a good job of mapping files to memory. So, as others
have stated, quad core is definitely a win in your case.  The other
thing to look closely at is the cache sizes. The 1.6Ghz vs. 2.0 Ghz is
minuscule, but make sure you don't get less cache. 

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9
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