Importance of number of CPU cores

Cases
1

Hi, im Sukyung

I want to ask about the relationship between GPU and CPU. I’m going to build a new computer for GPU-based calculations. I wonder if the number of cores is important when calculating GPUs. Now, I am using 4*RTX 3090 ti GPU and doing ILES calculation through Backend cuda.

Question1
Does each gpu use one core unconditionally?The processor number changes, but four always seem to be 100%.
cpu0

Question2
I have seen an increase in the overall cpu share periodically
cpu

Is this related to [soln-plugin-tavg] or [soln-plugin-fluidforce?] … (soln-plugin]?
If it is related to this, does the more CPU cores, the less calculation time when i use backend-cuda? Does the low cpu core take a long time or affect the overall calculation time?

2

Generally, when running on a GPU based platform, PyFR needs one core per GPU. Some plugins are able to indirectly make use of more cores, although the benefit here is not typically substantial.

Regards, Freddie.

3

When one GPU uses one core of CPU, does the performance of the CPU also greatly affect the simulation time?

4

So long as each GPU has a reasonable amount of work to do (above say 10,000 elements) then CPU performance is not important. If the GPUs are less loaded it can have a small impact.

Regards, Freddie.