when to use mma and wmma instructions

[wzhcz8902]

mma and wmma instructions are both used to do mma computation, and there are several files about these two instructions under cutlass/arch, just eager to know which circumstances each of them is used.

[hwu36]

wmma is easier to use, but slower. mma.sync ptx is hard to use, but faster. it is hard to use because it takes some effort to prevent shared memory bank conflict.