HPC FAQ: Difference between revisions
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If running on the same CPU hardware, a well-constructed Classic model on a good timestep is nearly always faster than HPC running on a single CPU thread (i.e. not using GPU hardware). Running a single HPC simulation across multiple CPU threads may produce a faster simulation than Classic. HPC is best run using GPU hardware. HPC run using good GPU hardware should be faster than Classic on CPU. The TUFLOW Wiki included guidance on the fastest available hardware for TUFLOW modelling.
=== Over utilisation of CPU threads/cores ===
Trying to run multiple HPC simulations across the same CPU threads. If, for example, you have 4 CPU threads on your computer and you run two simulations that both request 4 threads, then effectively you are overloading the CPU hardware by requesting 8 threads in total. This will slow down the simulations by more than a factor of 2. The most efficient approach in this case is to run both simulations using 2 threads each, noting that if you are performing other CPU intensive tasks, this also needs to be considered.<br>
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By default, the number of CPU threads taken is two (2). You can control the number of threads requested by either using the -nt<number_threads> run time option, e.g. -nt2, or use the .tcf CPU Threads. The -nt run time option overrides CPU Threads.<br>
Note: If Windows hyperthreading is active there typically will be two threads for each physical core. For computationally intensive processes such as TUFLOW, it is recommended that hyperthreading is deactivated so there is one thread for each core. ▼
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▲Note: If Windows hyperthreading is active there typically will be two threads for each physical core. For computationally intensive processes such as TUFLOW, it is recommended that hyperthreading is deactivated so there is one thread for each core.
=== Poor GPU Hardware ===
If running a simulation using a low end or old GPU device, simulations may only be marginally faster, than running Classic or HPC on CPU hardware. If running on a GPU device, high end NVidia graphics are strongly recommended. The performance of different NVidia cards varies by orders of magnitude – for hardware benchmark tests results please see the TUFLOW Wiki.
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