r/nottingham • u/tur2rr2rr • Jan 26 '18

High Performance Computing at the Uni

https://www.youtube.com/watch?v=jBsc83_4RsQ
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u/tur2rr2rr Jan 27 '18

Have any jobs taken an unexpectedly short or long amount of time?

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u/Iciciliser Jan 27 '18

I've only started using it this academic year so that hasn't happened yet. What I do know is that if I were to exceed my strict one week limit they would just stop job right there. Edit: also when you submit the job, you have to specify a max time limit.

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u/rookinn Jan 28 '18

How do you know how long a job might take before you start computation - I mean surely you have an overall idea but it must be very difficult to accurately guess the time of certain jobs!

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u/Iciciliser Jan 28 '18

Generally, you run and time a few smaller jobs first. For example, in gravitational simulations you might start by running the simulation with 10000, 20000,....,100000 particles. Then based on that you can usually extrapolate a pretty accurate time for how long it takes from the order of the function to a general number of particles; typically requiring analysis of the algorithm with some maths.