[petsc-users] superlinear scale-up with hypre

[Christian Klettner]

Dear PETSc,
I am using a fractional step method to solve the Navier-Stokes equation
which is composed of three steps. I have to solve a Poisson equation for
pressure in Step 2 and I use the GMRES solver with Hypre's BoomerAMG for
preconditioning. I have tested for strong scaling using a fixed problem
size of 16million degrees of freedom and varied the number of cores from
32 to 256. I have found superlinear speedup up until this number of cores.
Is there a reason why BoomerAMG exhibits this kind of behaviour?

Best regards,
Christian