How to check the best pack data's memory layout?

[Leslie-Fang]

Take matmul for example, will ruy bind each kernel with specific data format?
The knowledge I know is that, the LHS has transpose to COL Major. So both LHS, RHS and Dest are COL-Major.
The LHS and RHS should be packed into a specific memory layout to accelerate computation.
So what's the exactly memory layout for a specific kernel?