utilize more than one logical cpu

  • Last Post 25 October 2017
  • Topic Is Solved
bombaglad posted this 25 October 2017


when doing any kind of simulations with ansys AIM 18.2, the solver seems to never use over 30% of the CPU capacity on my i3-5005U, and over 750MB of my 8GB RAM. now, i know that this is by no means a high end setup, but i still don't get why the program essentially uses only one logical CPU. when doing a FEM analysis in catia, it uses all the cpu it can get, but this program seems to limit itself without any reason. i haven't found any setting that would help, nor any other way to force the program to simulate faster. any ideas?

Attached Files

Order By: Standard | Newest | Votes
bombaglad posted this 25 October 2017

wow, thanks a lot, this totally does the job

peteroznewman posted this 25 October 2017

First click on the Physics block, then under Physics Solution click the Solver Options link, then select Launch Controls 1.


I have a 4-core laptop that is configured for hyperthreading which allows two threads per core, so the Task Manager Performance tab shows 8 CPUs. You should only type in 4 not 8 for the number of processors in this example. ANSYS will only reach about 50% utilization on the Task Manager Performance tab as it uses "real" cores, not threads.

The default is 2 processors, so if you have a 4-core computer with hyperthreading turned on, you would expect to see an average of 25% usage on the Task Manager while the solver is running on 2 cores.

I also have a 16-core desktop where I disabled hyperthreading (per ANSYS recommendations) and I can see 100% utilization on the Task Manager when ANSYS is running and I let it use all 16 cores.


When I am using ANSYS Mechanical rather than AIM, I can see if the solver is running in RAM only (incore) or needs to use the disk (out-of-core) because the solver estimated that it could not run in RAM only. When I see the solver is running out-of-core, I might choose to stop the solution and reduce the mesh density to try to get an incore solution, which will take less time to solve. I don't think AIM has that degree of visibility on how it is solving, but since it uses the same solver, I assume it tries to solve in RAM if possible.