Fande Kong <[email protected]> writes: > * mpirun -n 8 ./ex5 -pc_type mg \ -ksp_monitor\ -pc_mg_levels 3 > \ -pc_mg_galerkin \ -da_grid_x 17 \ -da_grid_y 17 > \ -mg_levels_ksp_norm_type unpreconditioned \ -snes_monitor > \ -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.5,1.1 > \ -mg_levels_pc_type sor \ -pc_mg_type \* > > > I run this script several times, but at each time, the residual norms have > some tiny differences ( these should not happen). For example:
Some messages are unpacked in the order in which they are received, rather than doing a moderately expensive sorting. There are some options to make VecScatter and other components reproducible, but this configuration might use a feature for which such an option has not been implemented (-vecscatter_reproduce helps a little in my test, but is not sufficient). The difference you're seeing is harmless, but if you have an application for which this is required (either to reproduce rare events for re-analysis of an unstable dynamical system or due to programmatic requirements that misunderstand error analysis of finite-precision arithmetic), we can hunt down any such places and provide an option to make it reproducible.
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