The Death of CPU Scaling – an ExtremeTech Article

I read this excellent ExtremeTech article by this morning. I’ve been wondering about this myself for the past couple years.

CPU technology seemed to be following a new path of “more is better” rather than worrying about the performance of just one core. In other words, to me anyway, it seemed as if Intel, AMD, and others had just decided that it was cheaper to stuff more processors into a slab than it was to actually design and create a single core that performed at a higher level. I’ve been noticing this trend for a few years now; ever since the Intel Core 2 Duo came out, I guess.

To be honest, and I must add that I’m no expert on this topic by a long shot, I haven’t really noticed a huge performance jump between my current AMD Phenom quad and my old AMD Athlon64 single core CPU. I’m sure there is a vast difference, at least there appears to be when perusing the spec sheets of these processors. However, for my purposes, they’re pretty much interchangeable on my system.

Hruska writes:

For decades, microprocessors followed what’s known as Dennard scaling. Dennard predicted that oxide thickness, transistor length, and transistor width could all be scaled by a constant factor. Dennard scaling is what gave Moore’s law its teeth; it’s the reason the general-purpose microprocessor was able to overtake and dominate other types of computers.

And further on:

For the past seven years, Intel and AMD have emphasized multi-core CPUs as the answer to scaling system performance, but there are multiple reasons to think the trend towards rising core counts is largely over. First and foremost, there’s the fact that adding more CPU cores never results in perfect scaling. In any parallelized program, performance is ultimately limited by the amount of serial code (code that can only be executed on one processor). This is known as Amdahl’s law.

Where is CPU technology headed? Will the corporate bean counters try to pressure the companies to satisfy their stockholder’s greed or will the drive to create a quality product prevail? All good questions. The answers will eventually affect all of us who use computers in some way on a daily basis; not to mention that fact that the world is run by computers these days. Without that little CPU in that cash register at your grocery store, that girl behind the counter can’t even figure out how to count out your change from your purchase. We’ve become dependent on this technology.

Sadly, I think it’s turning us all into mushbrains. However, that’s a topic for another time.



Further reading: The death of CPU scaling: From one core to many — and why we’re still stuck – By on February 1, 2012 on