matmul in TF2

Hi, how do you modify your matmul.py to TF2?
https://github.com/yaroslavvb/stuff/blob/master/matmul_benchmark.py

I tried and replaced `opt_level=tf.OptimizerOptions.L0` with the following
`tf.compat.v1.OptimizerOptions(opt_level=-1)`

but there is huge variation from run to run.