RPI cluster performance related to network performance


I’m writing my thesis and i have built a RPI cluster, containing 10 nodes which consists of RPI model 3b. I’ve them connected to two gigabit switches. I don’t know the CAT of the cables. They are not connected to the Internet, they just live in their private network.

Further more, i’ve calculated the theoretical performance by the formula:

number of cores * average frequency * 16 FLOPs/cycle = x GFLOPS (Got the formula from https://www.slothparadise.com/how-to-run-hpl-linpack-across-nodes/ )

after i applied it, it turns out i should have 76,8 GFLOPS in theory assuming that the source is relaiable and correct. When i benchmark it using HPL 2.1 i’ve only reached little about 7 GFLOPS at best when trying out various variations.

Now to my question: i’ve read up on the RPI model, and it says it only have 10/100 Ethernet. Is that the source of my problem? Seeing i get out GFLOPS from a node, but the network transportation is much less then Gigabit speed which would mean 76,8 GFLOPS * 0,1 Gigabit/second = 7,68 GFLOPS (in theory). Or am i way off the tracks in my thinking?

I really appriciate any help, so i can know if i have to keep working on the configuration for the benchmarking or if i can move on. Also, i’m sorry if i have posted in the wrong place.

Stay safe out there!