The Register needs to ask better power questions

Thursday Sep 13, 2007

The register really needs to start asking tougher questions about power. A new article "Researchers: AMD less power-hungry than Intel" by Austin Modine.

This article just takes the results and ignores the really tough questions facing datacenters and power. I'll help here...

• What is the power draw of large memory configurations 16GB, 32GB, 64GB. The 2GB to 8GB used in this report are tiny for those making decisions in many datacenters.
• If you have racks and racks of idle servers (even servers at 30% utilisation) you are major problems and should be counting on new servers to save power!!!
• It is Watt/Performance (like $/perf) not perf/watt, as this highlights efficiency.
• CPU utilisation needs to be reported, if you are measuring at less than 60% you are wasting 2 TIMES to 5 TIMES more power per unit of work!
• Everyone needs to realize the variability of power measurements and not report differences as ##.#% - what? one simply doesn't have one-tenth of 1% reproducibility in power measurements of servers.

Focusing on small memory tries to focus on CPU power which is fine for chip vendors, but it is frankly no what customers I talk to care about. Customers care about full system ("car not piston performance").

The results show that under certain configurations and load levels, the Intel server was 2% to 12% per cent more power efficient. But in a majority of cases, the AMD server was 9% to 23% per cent more efficient.

These are tiny differences. Not enough testing was done to show if these results are consistent (power measurement has big run-to-run variations due to the complexity of most systems.

AMD server was 30% to 53% more power efficient. If accurate, it's a noteworthy figure, considering many servers spend the most of their time waiting for work.

WHAT?!?!? Datacenters idle? this is insane, maybe in extremely poorly run datacenters. Actually, if this the case, those people running the datacenter should find other jobs and not run datacenters.

On the whole, NN&A's tests showed that Intel's power efficiency decreases as memory size increases. Conversely, AMD's power efficiency increases as the memory is upped.

Intel, of course, disputes the results.

"The report doesn't measure our latest Xeons, or quad cores," said Intel rep Nick Knupffer in an email. We have 2 GHz quad cores in the market at 50 watts, 12.5 per core!"

I'll agree with Intel's criticism about latest CPUs and QCs, but even in the Intel statement they quickly talk about 2GHz QC and not the full GHz ones. Everyone loves to talk performance of high-GHZ CPUs and low-power of low-GHz CPUs, so watch for the confusing marketing and much worse "bait&switch." Also watts per core is useless marketing, it is the watt/perf for a system that counts.

NN&A's white paper http://www.worlds-fastest.com/d.pdf/wfw991.pdf

Also take a look at: http://blogs.sun.com/bmseer/entry/saving_the_planet_one_datacenter

If you want to see big power savings (not the small percentages talked about above!) take a look at: http://blogs.sun.com/ValdisFilks/entry/another_win_for_ecological_computing

...it is far too late, enough writing for today.