no parallel speedup with slepc krylovschur

[Christian May]

Dear readers,

I want to solve the following generalized eigenvalue problem in parallel:

http://www.phys.ethz.ch/~cmay/binaryoutput.tgz
(gnu zipped tar of the binaryoutput you get using -eps_view_binary)

I know the approximate value of the lowest eigenvalues I'm interested in, 
so I'm using shift-and-invert with the following options:

-eps_type krylovschur -st_type sinvert -st_shift -0.228 -eps_ncv 32 
-eps_nev 16 -eps_tol 1e-10


However, when I use multiple CPUs, I cannot see any speedup. I am not sure 
whether this is a problem of the matrix or of my system. Can anybody 
please have a look?

Thanks
Christian