I need to generate data samples for my thesis, using some R/C++ code I've written. It can be embarrassingly parallel, and I've generalized it to run on local multicore machines without much trouble.
On my Core2Duo it takes about 8 seconds to generate one sample, all are roughly the same, and ideally I'd like millions or tens of millions, so I was thinking about throwing it on EC2 for a few hours. Assuming one of their cores is comparable in performance to my C2D, 1m samples should take 2200 core-hours, give or take, ~70hrs on a 32 core machine.
I want to figure out how long this will take with reasonable confidence, so I thought I'd jump on a free micro instance, run some tests, and assume that compares to the larger costlier machines. Except the job I submitted (a for loop generating 100 samples 50 different times) should take <12 hours, but now I'm running into hour 28. This suggests that either the cores are much slower than I expected, or else my jobs are low priority and I'm getting uneven performance.
Say I'm interested in renting 1-3 32 core machines for a day or two. How could I estimate how long this might take?