[X4U] Re: Expandable Macs [a]

[Eugene]

On Tue, Jan 22, 2008 at 10:40:57AM CST, Zane H. Healy <healyzh at aracnet.com> wrote:
> At 4:39 AM +0000 1/22/08, Stroller wrote:
>>
>> I've never been sure that an extra core is as good as an extra processor, 
>> but feel I'm unlikely to complain over the speed of a quad-core Xeon.
>
> The thing to remember about Multi-CPU systems is that it doesn't matter how 
> good they are, a second CPU doesn't make your system 2x as fast.  Likewise 
> a dual 4-core system won't be 8x as fast.  OTOH, those new Xeon CPU's have 
> 12Mb L2 cache per CPU vs. 2-4Mb on the Core 2 Duo.  That makes a real 
> difference.  Of course how well written what you're running makes a 
> difference as well.  A single threaded app will only run as fast as a 
> single core.

If you recall the old megahertz wars, Intel was running into bottlenecks
where higher clock frequencies were no longer translating to one-to-one
performance improvements in terms of (name your benchmark) instructions
per second.


-- 
Eugene
http://www.coxar.pwp.blueyonder.co.uk/