Archive for July, 2012

How to silently turn your brand new 2×48-core Dell machine into a Pentium 4

Saturday, July 21st, 2012

In the lab we recently bought two bleeding edge PowerEdge C6145s. Each has two servers with 48 2.5GHz cores. That’s a pretty big bang for your 2U. The danger with brand new hardware is that you also get brand new bugs and Dell, who was as confused as we were, didn’t let us down at all. One of the new boxes felt slow, real slow. Actually, per-core it was on par with my cellphone, 3.1 times slower than the other box. The machines are identical in every way. Turns out after lots of time wasted trying to figure out how the machines are different from each other, one of the power supplies had a yellow light and resetting it fixed the problem. But the strange part was that /proc/cpuinfo never showed any hint of frequency scaling even thought it must have been happening in the background anyway. More hardware, more problems…