Thursday, July 21, 2011

Cable Drama (Not of the Soap Variety)

Let me begin with a sincere thank you to to the folks at Microsoft Research in Mountain View for donating a WattsUp meter friendly USB cable. Anyone who has to depend on these meters knows their cables can't be easily replaced with a quick trip to the store. This is due to the recessed port on the actual meter.

The story behind this donation revolves around two WattsUp meters [see left in the red circles].

One of these meters began to return too many errors and bad packets. Not a problem, we avoided it by changing the setup so the Machine Under Test (MUT) uses the "good" meter. Switching the two computers between this "good" meter did cause a minor headache because it left room for errors to happen. For each workload we wanted to run on both boxes (meaning all benchmarks) we would have to swap meters. This meant shutdown the computers, unplug a great many cables and hope things didn't get messed up when the cables were then plugged into their new configuration.

How does a new cable play into this meter drama? Last time we re-configured the wiring our "good" meter began to exhibit the same behavior as the "bad" meter. This time the only thing changed were the usb cables on the meters relaying the data from the MUT's meter to the Data Acquisition Machine. Turns out both meters work fine, it was a dud cable.

Dr. Rivoire, our faculty adviser, in her research at Microsoft, had recently replaced cables on the WattsUp meters used in her research there because of a similar problem. QED let's change out the cable. In short the bottleneck on progress has be resolved thanks to a coworker of Dr. Rivoire's for cutting and refitting the casing on a USB cable to fit WattsUp's unique recessed port.

Workloads ahoy I'll finally have a chance to use my new parsing script written in perl abusing some tricks of regular expressions & unique logs.

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