Question about performance comparison

Hi.
I was looking for a performance comparison between `ruy` and `OpenBLAS` and I came across [this](https://github.com/google/ruy/issues/270#issuecomment-862699301).
But when I benchmark the ruy (almost for any shape with single thread execution and on raspberry pi 4), my results are far behind the reported results.
For example, for the 512x512x512 Int8 benchmark, I can only get ~10 GOPs but excel reported 40 GOPs.
I know Raspberry Pi 4 CPU frequency can be maxed out to 1.5 GHz while Pixel 4 max frequency is 2.84 GHz, but it does not justify the 30 GOPs gap.
So I thought it might be better to ask it here.
How did you measure GOPs for ruy?
I calculate the GOPs for the method with the `((2 * N * K * M * iterations) / time) / 10e+9` formula (`time` is the sum of the execution time of `ruy::Mul` for each iteration) (I pack the RHS matrix beforehand).
Am I doing anything wrong?