Thursday, December 30, 2010

Some situations where power efficiency isn't the desired answer

Here's an interesting collection of inter-related notes about people who were surprised when their brand new spiffy computers were running substantially slower than their old computers:

The bottom line is that modern CPUs are incredibly sophisticated, and are capable of dynamically speeding up and slowing down in response to their workload, running faster (and using more power, generating more heat, etc.) when they need to get lots of work done, but automatically slowing themselves down when they aren't busy.

However, as Jeff Atwood and his team at StackOverflow found, sometimes this automatic speedup/slowdown functionality doesn't work right, and the only thing that you might notice is that your brand new server is running slower than your old one. Gotta love this perspective on the behavior:

My hat is off to them for saving the planet by using less power, but my pants are down to them for killing performance without informing the users. In the last few weeks, I’ve seen several cases where server upgrades have resulted in worse performance, and one of the key factors has been throttled-down CPUs. In theory, the servers should crank up the juice according to demand, but in reality, that’s rarely the case. Server manufacturers are hiding power-saving settings in the BIOS, and Windows Server ships with a default power-saving option that throttles the CPU down way too often.

Jeff Atwood is an incredibly alert and aware programmer; I have to wonder how many other users out there are being bit by this behavior and are completely unaware that it is occuring to them.

It looks like there is a CPUID tool available from Intel for Mac OS X: MacCPUID. It seems to work on my system, though it's hard to compare it to the CPU-Z screen shots from the articles above. Is there a better tool to run on a Mac OS X system?

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