Solved by tom in post #4 
              
              
                If you have 4 cores and need to do, say, 8 matrix multiplications (with separate data) you could use 4 cores to do each matrix multiplication (intra-op-parallelism). Or you could use a single core for each op and run 4 of them in parallel (inter-op-parallelism). 
In training, you also might want to …