[firedrake] Measure fieldsplit/AMG setup time separately

[Eike Mueller]

Dear firedrakers,

how can I enforce the setup of the entire PETSc solver when the object is created? I use the fieldsplit preconditioner with AMG for the pressure space.

What I currently do is

        up_problem = LinearVariationalProblem(a_up, L_up, vmixed, bcs=bcs)
        up_solver = LinearVariationalSolver(up_problem, solver_parameters=sparams)
        ksp = up_solver.snes.getKSP()
        ksp.setUp()
        pc = ksp.getPC()
        pc.setUp()

But that does not seem to work, since I still see that the first iteration of the subsequent solve call is much larger.

I also noticed that on ARCHER the setup time is ridiculously large (200x larger than 1 iteration), and I don’t observe this on my laptop. Has anyone seem similar behaviour on ARCHER?

Thanks a lot,

Eike