Did you get a chance to run as I requested with "Please run with -ksp_view and send the output."
We are eager to determine the problem. Barry On Mar 16, 2011, at 11:03 AM, Barry Smith wrote: > > On Mar 16, 2011, at 8:57 AM, Thomas Witkowski wrote: > > -pc_fieldsplit_type schur -fieldsplit_interior_ksp_type preonly > -fieldsplit_interior_pc_type bjacobi -fieldsplit_interior_sub_pc_type lu > -fieldsplit_boundary_ksp_monitor -ksp_monitor_true_residual > > >> Residual norms for fieldsplit_boundary_ solve. >> 0 KSP Residual norm 1.790059331071e-04 >> ..... >> 18 KSP Residual norm 1.593454221996e-09 >> 0 KSP preconditioned resid norm 5.745043818120e-01 true resid norm >> 1.584249437360e-01 ||r(i)||/||b|| 1.000000000000e+00 > This is the norms on the outer iteration variables >> Residual norms for fieldsplit_boundary_ solve. >> 0 KSP Residual norm 1.790059331000e-04 > This is the norms on the Schur complement iteration >> .... >> 18 KSP Residual norm 1.593449602302e-09 > > It is unclear to me why it starts up another solve here, starting > basically where it left off. I think it should just kick out to print the > norm of the residual of the outer iteration. > >> Residual norms for fieldsplit_boundary_ solve. >> 0 KSP Residual norm 1.593449603155e-09 >> ... >> 18 KSP Residual norm 1.335744434252e-14 >> 1 KSP preconditioned resid norm 2.608069232839e-13 true resid norm >> 1.449869994655e-13 ||r(i)||/||b|| 9.151778504469e-13 >> > > Are you running with petsc-dev? > > Please run with -ksp_view and send the output. > > When I run tutorials/multiphysics/mp.c with the options ./mp -couple > -snes_monitor_short -pc_type fieldsplit -ksp_monitor -pc_fieldsplit_type > schur -fieldsplit_ksp_monitor -fieldsplit_1_ksp_type fgmres > -fieldsplit_0_ksp_type gmres -snes_view I do not see the "double" iteration > business. > > Barry > > > >> >> So, are there now two or one outer iterations? >> >> Thomas >> >> >> >> >> Matthew Knepley wrote: >>> On Wed, Mar 16, 2011 at 8:27 AM, Thomas Witkowski <thomas.witkowski at >>> tu-dresden.de <mailto:thomas.witkowski at tu-dresden.de>> wrote: >>> >>> Jed Brown wrote: >>> >>> On Wed, Mar 16, 2011 at 07:37, Thomas Witkowski >>> <thomas.witkowski at tu-dresden.de >>> <mailto:thomas.witkowski at tu-dresden.de> >>> <mailto:thomas.witkowski at tu-dresden.de >>> <mailto:thomas.witkowski at tu-dresden.de>>> wrote: >>> >>> Thanks for explanations! It works fine in my code. But I >>> have two >>> questions about it, maybe you can help me with them: >>> - To the first, is the LU factorization on block A_00 done >>> only once? >>> >>> >>> Yes, one way to confirm this is to run with -log_summary and >>> check MatLUFactor{Sym,Num}. >>> - I have run the code with -fieldsplit_1_ksp_monitor to >>> get >>> some >>> more information about the internal solves. I expected to get >>> information about one iterative solver (for solving the Schur >>> complement system), but I got three, all of them need around 20 >>> iterations for my example. Could you explain to me what is >>> actually solved there? >>> >>> >>> I'm going to guess that you still have an outer KSP that (in >>> the global norm, rather than the partitioned norm used inside >>> of splits) has a tighter tolerance, therefore it takes a few >>> outer iterations. If you use loose inner tolerances then the >>> preconditioner becomes nonlinear and you'll need to use FGMRES >>> for the outer. When in doubt, run with -ksp_view and show us >>> the results if you don't understand. Additionally, monitoring >>> inner solves separately can be useful, e.g. >>> -fieldsplit_0_ksp_converged_reason -fieldsplit_1_ksp_monitor >>> -ksp_monitor_true_residual. >>> >>> Okay, I run my code with the options "-pc_fieldsplit_type schur >>> -fieldsplit_interior_ksp_type preonly -fieldsplit_interior_pc_type >>> bjacobi -fieldsplit_interior_sub_pc_type lu >>> -fieldsplit_boundary_ksp_monitor -ksp_monitor_true_residual >>> -fieldsplit_interior_ksp_converged_reason". The splits are named >>> "interior" and "boundary". The ksp output is as follows: >>> >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> Residual norms for fieldsplit_boundary_ solve. >>> 0 KSP Residual norm 1.790059331071e-04 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 1 KSP Residual norm 1.237356212928e-04 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 2 KSP Residual norm 7.952220245101e-05 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 3 KSP Residual norm 3.502858665398e-05 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 4 KSP Residual norm 1.601085190129e-05 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 5 KSP Residual norm 8.491161243057e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 6 KSP Residual norm 4.778227395989e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 7 KSP Residual norm 2.571919352633e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 8 KSP Residual norm 1.353979940120e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 9 KSP Residual norm 7.408377337496e-07 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 10 KSP Residual norm 3.810694345834e-07 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 11 KSP Residual norm 1.955889542056e-07 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 12 KSP Residual norm 9.938906113920e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 13 KSP Residual norm 4.893445675773e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 14 KSP Residual norm 2.395128458062e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 15 KSP Residual norm 1.2464425896 <tel:1.2464425896>57e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 16 KSP Residual norm 6.316454504022e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 17 KSP Residual norm 3.088668836241e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 18 KSP Residual norm 1.593454221996e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> [0] Petsc-Iteration 0: 0.574504 >>> 0 KSP preconditioned resid norm 5.745043818120e-01 true resid >>> norm 1.584249437360e-01 ||r(i)||/||b|| 1.000000000000e+00 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> Residual norms for fieldsplit_boundary_ solve. >>> 0 KSP Residual norm 1.790059331000e-04 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 1 KSP Residual norm 1.237356237744e-04 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 2 KSP Residual norm 7.952220078415e-05 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 3 KSP Residual norm 3.502859285561e-05 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 4 KSP Residual norm 1.601086485810e-05 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 5 KSP Residual norm 8.491169384185e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 6 KSP Residual norm 4.778229157872e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 7 KSP Residual norm 2.571917112191e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 8 KSP Residual norm 1.353977280183e-06 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 9 KSP Residual norm 7.408352317360e-07 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 10 KSP Residual norm 3.810710583336e-07 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 11 KSP Residual norm 1.955898169394e-07 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 12 KSP Residual norm 9.938892788465e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 13 KSP Residual norm 4.893428546840e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 14 KSP Residual norm 2.395120857135e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 15 KSP Residual norm 1.2464367927 <tel:1.2464367927>84e-08 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 16 KSP Residual norm 6.316409779118e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 17 KSP Residual norm 3.088649355374e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 18 KSP Residual norm 1.593449602302e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> Residual norms for fieldsplit_boundary_ solve. >>> 0 KSP Residual norm 1.593449603155e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 1 KSP Residual norm 1.011857676662e-09 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 2 KSP Residual norm 5.660892669788e-10 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 3 KSP Residual norm 3.046799343903e-10 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 4 KSP Residual norm 1.6004713993 <tel:1.6004713993>29e-10 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 5 KSP Residual norm 8.083216601016e-11 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 6 KSP Residual norm 4.308671648345e-11 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 7 KSP Residual norm 2.381959817139e-11 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 8 KSP Residual norm 1.264839790114e-11 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 9 KSP Residual norm 6.435098853282e-12 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 10 KSP Residual norm 3.184769579797e-12 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 11 KSP Residual norm 1.5022019430 <tel:1.5022019430>16e-12 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 12 KSP Residual norm 7.099486208425e-13 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 13 KSP Residual norm 3.443222176388e-13 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 14 KSP Residual norm 1.6478434989 <tel:1.6478434989>12e-13 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 15 KSP Residual norm 8.208508173926e-14 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 16 KSP Residual norm 4.376604355287e-14 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 17 KSP Residual norm 2.596069152755e-14 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 18 KSP Residual norm 1.335744434252e-14 >>> Linear solve converged due to CONVERGED_ITS iterations 1 >>> 1 KSP preconditioned resid norm 2.608069232839e-13 true resid >>> norm 1.449869994655e-13 ||r(i)||/||b|| 9.151778504469e-13 >>> >>> I have no idea how to interpret this output! Could you help me >>> with it? >>> >>> >>> Get rid of -fieldsplit_interior_ksp_converged_reason. It is confusing >>> things. Then you will see >>> the outer iteration and the inner boundary iteration which is indented. >>> >>> Matt >>> >>> >>> Thomas >>> >>> >>> >>> >>> -- >>> What most experimenters take for granted before they begin their >>> experiments is infinitely more interesting than any results to which their >>> experiments lead. >>> -- Norbert Wiener >> >
