Confused About Processors

For the first time in as long as I can remember, I’m utterly at a loss as to which processor is faster—or whether buying a server with a new processor (or even multiple processors) will make the slightest bit of difference in terms of overall performance of our web site.

Back in the day, it was easier to say whether a new processor would be faster than an old one: just look at the clock speed. 1.6 GHz smoked a 800 MHz processor; 2.4 GHz was better still, and 3.6 GHz was the best you could buy. But then heat factors put an end to simple clock speed races and Intel and AMD turned to multiple processors, multiple cores, different piplelining schemes, and so on.

I’ve heard the advice that multiple cores and processors are essentially worthless unless you’re running a machine specifically geared toward using the multiple cores. But how then, is a 2.4 GHz Core 2 Duo noticeably outperforming my 3.4 GHz Pentium at most regular desktop work—none of which (that I can see) has been optimized to work with two processors?

Then there’s the question of our web servers: when running Windows Server 2003 and IIS 6, is there any advantage at all to upgrading our 3.0 GHz Xeon processor-based servers to whatever the top-of-the-line offerings from Dell or Supermicro are? So far as I can tell, the major bottlenecks for web servers are bandwidth (not immediately upgradeable), disk (we’re already running fast SATA drives in RAID configurations), and only then the processor speed. That said, kicking off compiles in ASP.Net does feel kind of slow to me, and I’d be willing to throw some cash at solving the problem…but I’d have to have some assurance first that throwing cash at it would actually make a noticeable difference in some metric I care about (# of web requests serviced, compile speeds, etc.)

Ideally, what I’d like to have a sense for is, “If I spend $X to buy Y, my <something I care about> will run Z% faster than it does now.” Several nights spent googling around on this score really haven’t yielded anything enlightening. I’ll admit it: right now, I’m at a loss.

Can anyone with real-world experience on our brave new world of processors kick in some words of wisdom on this subject?

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One response to “Confused About Processors

  1. I didn’t buy the dual-core thing for a while myself. I had a P4 3.4 single core Prescott (some called ’em “Press-HOTs”) for a long time and then Intel started trotting out these 1.x GHZ Dual-core CPUs. I was like “why would I want to drop 2 GHZ in speed to get a dual-core chip???? After a LOT of discussion (and even more research into benchmarks and what not) I finally seen the light. They really are WAY FASTER and clock speed just doesn’t tell the tale when you compare single to dual. There are several article over on Arstechnica that may help:

    http://arstechnica.com/articles/paedia/cpu/intel-future.ars

    http://arstechnica.com/articles/paedia/cpu/prescott.ars

    – Larry Robertson

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