[petsc-users] MatCreate performance

[Ale Foggia]

Hello all,

I have a problem with the scaling of the MatCreate() function. I wrote a
code to diagonalize sparse matrices and I'm running it in parallel. I've
observed a very bad speedup of the code and it's given by the MatCreate
part of it: for a fixed matrix size, when I increase the number of
processes the time taken by the function also increases. I wanted to know
if you expect this behavior or if maybe there's something wrong with my
code. When I go to (what I consider) very big matrix sizes, and depending
on the number of mpi processes, in some cases, MatCreate takes more time
than the time the solver takes to solve the system for one eigenvalue or
the time it takes to set up the values.

Ale
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