Only 50% CPU usage : normal or not ?

Hello,

I am running simulation with FEKO and was wondering if the 50% CPU print by my task monitor was normal or not

I have TWO cpus on my machine, both with 32 cores (AMD EPYC 9374F 32-Core Processor, 3850 MHz)

—> My simulations are set up as to use 64 processes, which they do. However, I wonder if this 50% percent is normal ? Should I have let say 80% and run simulations faster ? Or am I misunderstanding something concerning the task monitor showing or anything else ?

Thanks a lot,

Pierre

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Shannon_Mistry

Hi @degleve_jarmlami,

This is generally normal as Task manager often displays the utilization against the total logical processors. This does not necessarily mean that Feko is not utilizing all the physical cores. You can actually look the the logical processors by going to Task manager>Performance> CPU and observe the logical processors.

Regards,

Shannon Mistry

degleve_jarmlami

Hello, thanks for the answer.

The thing is I got 62 physical cores but if I specify more threads, it run faster, and CPU usage get up maybe 70%.

So I understand so optimization would be possible here I don't really know how, concerning how it works in the CPU. Would you have some thoughts about it ? Or maybe someone at Altair who get their hands in the engine background ?

Thanks a lot !

Pierre

Mahan Rudd_22044

Hi @degleve_jarmlami ,

if you have 64 physical cores and using all of them for the simulation you should be able to push the CPU usage shown in task manager close to 100%. The CPU usage should reduce as you assign fewer cores to the Feko job (obviously assuming that your system is not running any other tasks/simulation to use the free cores). I have seen some older versions of Feko running on the Windows OS on AMD machines not being able to utilize the full capacity of the CPU without some additional environment variables settings. This needs to be checked more in details so I would suggest you contact your account manager/local support team to have a closer look. Some settings that might help (assuming you are using Windows):

If the CPU supports hyperthreading turn that off.

Check the list of windows environment variables and make sure NUMBER_OF_PROCESSORS is set correctly

Set FEKO_AFFINITY_SET=1 environment variable

Try changing the MPI to MS-MPI. You can find the instruction below:

https://community.altair.com/discussion/41569/altair-feko-how-to-set-up-microsoft-mpi-ms-mpi

Hope that helps.

Regards

Mahan

degleve_jarmlami

Hello,

Thanks for your answer.

I think we are not talking about exactly the same thing here.

In my specific case, with 64 physical cores, I can ask feko to run more than 64 threads. As a result, simulation time is reduced, and CPU usage shows more something like 70%.

So my question is if this is the good practice to do the simulation ? Or am is it not normal in any ways ?

Thanks !

degleve_jarmlami

Hello ! Where you able to get some updates ?

Thanks ! :)

Mahan Rudd_22044

Hi @degleve_jarmlami ,

Technically you can ask Feko to run the simulation with any number of parallel processes (component launch options—>Feko solver—>Parallel execution). However, if you set the number of parallel processes to a value greater than available physical core, it is usually less efficient. That doesn't seem to be the case for your scenario and you are saying you are getting a better performance when setting the number of processes to a value greater than the available physical cores. This is strange and could be due the way OS/MPI handles the parallel processes for that AMD CPU architecture. The settings I mentioned in my previous response might be helpful. Normally you should be able utilize (close to) 100% of the CPU capacity by setting the number of parallel processes to the actual number of physical cores. This would be the best performance you can get from your hardware.

You shouldn't need to set the number of parallel processes to a value greater than the actual number of physical cores to achieve higher CPU usage.

I hope this clarifies my previous answer.

Regards

Mahan

degleve_jarmlami

Hello,

Okay I get what you mean. So this is weird, I'll investigate further.

Thanks !