[petsc-users] MatMatMult takes much time

[Alexander Grayver]

Hello,

call 
MatMatMult(S,G,MAT_INITIAL_MATRIX,PETSC_DEFAULT_DOUBLE_PRECISION,J,ierr);CHKERRQ(ierr)

I use this operation to compute matrix-matrix product. It's correct, but 
quite slow.

For instance, my matrix S is a dense matrix size of <6x762048 complex 
double> and matrix G is a sparse matrix with 2 nonzeros per row and size 
of <762048x254016 complex double>
Time spent on S*G was ~22 secs with 32 processes over 4 nodes. There is 
infiniband between nodes.

Is it a real life or I'm doing something wrong?

Regards,
Alexander