IPP provide small matrix operation functionsin ippm.pdf,Unlike MKL, whichis usually forengineeringand scientificcomputation, ippm functionsare optimizated for small matrix. So the preferred size generallyranges from 3x3 to 20x20.
We are optimized many IPP functions using AVX instructions. Refer to list to get details.
My recommendation is to refer to an article on intel site Benefits of Intel AVX For Small Matrices