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Re: Triax profiling on cluster


So if you use 5 threads on 16 CPU machine, and 11 other CPUs are
idle, you will be twice faster than when you use 5 CPUs and 11 other
CPUs are used by someone else for other calculations. That's because
Intel has very slow RAM access (contrary to AMD).

Oh, I get it! I'm not alone on a machine. The workaround would be to require 16 threads for the full test to keep the other threads idle (still no guarantee since the grid engine could give me 8 proc. on one core + 8 proc. on another...).

Therefore making benchmarks on cluster makes little sense, you will
get random results. (Unless you talk with everyone else to stop doing
their calculations ;). I was doing calculations for several months,
and I had 'htop' running of every node and I was noting down whether
I am calculating alone, or if others are also using CPU. And those
above were my observations.

Did you try the "big cache" option? It allows you to skip RAM access and use the internal memory attached to the node. Remi said it can speed up "some" jobs a lot.



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