On Fri, Feb 24, 2012 at 14:43, Francis Poulin <fpoulin@uwaterloo.ca> wrote:

It seems to scale beautifully starting at 2 but there is a big drop from 1 to 2. I suspect there's a very good reason for this, I just don't know what.

Can you send the full output? The smoother is slightly different, so the number of iterations could be different by 1 (for example). The -log_summary part of the output will show us where the time is being spent, so we'll be able to say what did not scale well between 1 and 2 procs.