Hi,
For the same sparse matrix, will the storage format (baij or aij) have a noticeable performance effect on MatMult give the baij may have a better locality?
The gains are mostly due to the reduced number of indices loaded from memory. For normal aij, each floating point number (typically 8 bytes) requires an index (typically 4 bytes, unless you use 64 bit indices).
With baij you only need one index per block. For example, if your block size is 3x3, only one index for 9 floating point numbers is needed. Thus, your performance gains are not going to be dramatic, but still... :-)
Best regards, Karli
