HPC FAQ: Difference between revisions
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*An explicit scheme that is parallelised will run a single simulation faster by around a factor of 5 on an 8 core machine – you will never get a mark-up of 8 on an 8 core machine as there is an overhead in managing the computations across the cores.
*Users are often doing two or more simulations at the same time. For example different events (100, 20 year…, different durations, etc). In these situations, even if a scheme is parallelised, it is usually better and sometimes much better, to run each simulation unparallelised on their own core. For example, if you have four simulations and four cores, definitely don’t run them parallelised, but run all four at once unparallelised. If a fifth simulation is started up this will then slow down the other simulations.<br>
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=What are the two times in my _TUFLOW Simulations.log?=
There are three pieces of information in this section of the file:<br>
<ol>[[File:TUFLOW simulations log.png]]</ol>
*In green is the 'clock time', i.e. the time that has elapsed on a clock. It is the time the simulation has finished minus the start time.
*In blue is the engine compute hardware.
*In red is the 'total processor time' that has been used for the simulation, including simulation start up. If multiple cores or GPU's have been used it is the total time across each core or GPU. For example, if 12 cores all compute for 10 minutes, the compute time is 12x10 min = 2 hours, despite only 10 minutes elapsing in clock time. If the simulation is set to use only a single core or GPU then this should be less than the clock time.
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