Send the output using -ksp_view Normally one uses a fixed number of iterations of smoothing on level with multigrid rather than a tolerance, but yes PETSc should respect such a tolerance.
Barry > On Sep 26, 2025, at 12:49 PM, Moral Sanchez, Elena > <[email protected]> wrote: > > Hi, > I am using multigrid (multiplicative) as a preconditioner with a V-cycle of > two levels. At each level, I am setting CG as the smoother with certain > tolerance. > > What I observe is that in the finest level the CG continues iterating after > the residual norm reaches the tolerance (atol) and it only stops when > reaching the maximum number of iterations at that level. At the coarsest > level this does not occur and the CG stops when the tolerance is reached. > > I double-checked that the smoother at the finest level has the right > tolerance. And I am using a Monitor function to track the residual. > > Do you know how to make the smoother at the finest level stop when reaching > the tolerance? > > Cheers, > Elena.
