Your shell matrix is buggy in some way. Whenever the residual norm jumps like crazy at a restart it means that something is wrong with the operator.
Barry On May 2, 2014, at 4:41 PM, Song Gao <[email protected]> wrote: > Dear PETSc users, > > I'm solving a linear system in KSP and trying to setup the solver in codes. > But I feel strange because my codes don't converge unless I call > KSPGMRESSetRestart twice. > > My codes looks like > > call KSPSetOperators ( pet_solv, pet_mat_mf_shell, pet_matp, > DIFFERENT_NONZERO_PATTERN, ierpetsc ) > call KSPSetType ( pet_solv, 'gmres', ierpetsc ) > call KSPGMRESSetRestart ( pet_solv, 30, ierpetsc ) > call KSPGetPC ( pet_solv, pet_precon, ierpetsc ) > call PCSetType ( pet_precon, 'asm', ierpetsc ) > call PCASMSetOverlap ( pet_precon, 1, ierpetsc ) > call KSPSetUp ( pet_solv, ierpetsc ) > call PCASMGetSubKSP ( pet_precon, n_local, first_local, pet_solv_sub, > ierpetsc ) ! n_local is one > call KSPGetPC ( pet_solv_sub(1), pet_precon_sub, ierpetsc ) > call PCSetType ( pet_precon_sub, 'jacobi', ierpetsc ) > call PCJacobiSetUseRowMax ( pet_precon_sub, ierpetsc ) > call KSPSetFromOptions ( pet_solv, ierpetsc ) > call KSPGMRESSetRestart ( pet_solv, 29, ierpetsc ) ! adding this > line, the codes converge > call KSPSolve ( pet_solv, pet_rhsp, pet_solup, ierpetsc ) > > runing with 1 CPU WITHOUT the line with red color and the codes don't > converge > > runtime options: -ksp_monitor_true_residual -ksp_view > 0 KSP preconditioned resid norm 6.585278940829e+00 true resid norm > 9.619278462343e-03 ||r(i)||/||b|| 1.000000000000e+00 > 1 KSP preconditioned resid norm 6.585278219510e+00 true resid norm > 9.619278462343e-03 ||r(i)||/||b|| 1.000000000000e+00 > 2 KSP preconditioned resid norm 2.198638170622e+00 true resid norm > 1.365132713014e-01 ||r(i)||/||b|| 1.419163317039e+01 > 3 KSP preconditioned resid norm 1.599896387215e+00 true resid norm > 1.445988845022e-01 ||r(i)||/||b|| 1.503219654865e+01 > ....... > 28 KSP preconditioned resid norm 4.478466011191e-01 true resid norm > 1.529879309381e-01 ||r(i)||/||b|| 1.590430420920e+01 > 29 KSP preconditioned resid norm 4.398129572260e-01 true resid norm > 1.530132924055e-01 ||r(i)||/||b|| 1.590694073413e+01 > 30 KSP preconditioned resid norm 2.783227613716e+12 true resid norm > 1.530369123550e-01 ||r(i)||/||b|| 1.590939621450e+01 > > KSP Object: 1 MPI processes > type: gmres > GMRES: restart=30, using Classical (unmodified) Gram-Schmidt > Orthogonalization with no iterative refinement > GMRES: happy breakdown tolerance 1e-30 > maximum iterations=10000, initial guess is zero > tolerances: relative=1e-05, absolute=1e-50, divergence=10000 > left preconditioning > using PRECONDITIONED norm type for convergence test > PC Object: 1 MPI processes > type: asm > Additive Schwarz: total subdomain blocks = 1, amount of overlap = 1 > Additive Schwarz: restriction/interpolation type - RESTRICT > [0] number of local blocks = 1 > Local solve info for each block is in the following KSP and PC objects: > - - - - - - - - - - - - - - - - - - > [0] local block number 0, size = 22905 > KSP Object: (sub_) 1 MPI processes > type: preonly > maximum iterations=10000, initial guess is zero > tolerances: relative=1e-05, absolute=1e-50, divergence=10000 > left preconditioning > using NONE norm type for convergence test > PC Object: (sub_) 1 MPI processes > type: jacobi > linear system matrix = precond matrix: > Matrix Object: 1 MPI processes > type: seqbaij > rows=22905, cols=22905, bs=5 > total: nonzeros=785525, allocated nonzeros=785525 > total number of mallocs used during MatSetValues calls =0 > block size is 5 > - - - - - - - - - - - - - - - - - - > linear system matrix followed by preconditioner matrix: > Matrix Object: 1 MPI processes > type: shell > rows=22905, cols=22905 > Matrix Object: 1 MPI processes > type: seqbaij > rows=22905, cols=22905, bs=5 > total: nonzeros=785525, allocated nonzeros=785525 > total number of mallocs used during MatSetValues calls =0 > block size is 5 > WARNING: zero iteration in iterative solver > > runing with 1 CPU WITH the line with red color and the codes converge > > runtime options: -ksp_monitor_true_residual -ksp_view > 0 KSP preconditioned resid norm 6.585278940829e+00 true resid norm > 9.619278462343e-03 ||r(i)||/||b|| 1.000000000000e+00 > 1 KSP preconditioned resid norm 2.566248171026e+00 true resid norm > 4.841043870812e-03 ||r(i)||/||b|| 5.032647604250e-01 > 2 KSP preconditioned resid norm 1.410418402651e+00 true resid norm > 3.347509391208e-03 ||r(i)||/||b|| 3.480000505561e-01 > 3 KSP preconditioned resid norm 9.665409287757e-01 true resid norm > 2.289877121679e-03 ||r(i)||/||b|| 2.380508195748e-01 > 4 KSP preconditioned resid norm 4.469486152454e-01 true resid norm > 1.283813398084e-03 ||r(i)||/||b|| 1.334625463968e-01 > 5 KSP preconditioned resid norm 2.474889829653e-01 true resid norm > 7.956009139680e-04 ||r(i)||/||b|| 8.270900120862e-02 > ............ > 24 KSP preconditioned resid norm 9.518780877620e-05 true resid norm > 6.273993696172e-07 ||r(i)||/||b|| 6.522312167937e-05 > 25 KSP preconditioned resid norm 6.837876679998e-05 true resid norm > 4.612861071815e-07 ||r(i)||/||b|| 4.795433555514e-05 > 26 KSP preconditioned resid norm 4.864361942316e-05 true resid norm > 3.394754589076e-07 ||r(i)||/||b|| 3.529115621682e-05 > KSP Object: 1 MPI processes > type: gmres > GMRES: restart=29, using Classical (unmodified) Gram-Schmidt > Orthogonalization with no iterative refinement > GMRES: happy breakdown tolerance 1e-30 > maximum iterations=10000, initial guess is zero > tolerances: relative=1e-05, absolute=1e-50, divergence=10000 > left preconditioning > using PRECONDITIONED norm type for convergence test > PC Object: 1 MPI processes > type: asm > Additive Schwarz: total subdomain blocks = 1, amount of overlap = 1 > Additive Schwarz: restriction/interpolation type - RESTRICT > [0] number of local blocks = 1 > Local solve info for each block is in the following KSP and PC objects: > - - - - - - - - - - - - - - - - - - > [0] local block number 0, size = 22905 > KSP Object: (sub_) 1 MPI processes > type: preonly > maximum iterations=10000, initial guess is zero > tolerances: relative=1e-05, absolute=1e-50, divergence=10000 > left preconditioning > using NONE norm type for convergence test > PC Object: (sub_) 1 MPI processes > type: jacobi > linear system matrix = precond matrix: > Matrix Object: 1 MPI processes > type: seqbaij > rows=22905, cols=22905, bs=5 > total: nonzeros=785525, allocated nonzeros=785525 > total number of mallocs used during MatSetValues calls =0 > block size is 5 > - - - - - - - - - - - - - - - - - - > linear system matrix followed by preconditioner matrix: > Matrix Object: 1 MPI processes > type: shell > rows=22905, cols=22905 > Matrix Object: 1 MPI processes > type: seqbaij > rows=22905, cols=22905, bs=5 > total: nonzeros=785525, allocated nonzeros=785525 > total number of mallocs used during MatSetValues calls =0 > block size is 5 > WARNING: zero iteration in iterative solver > > > What would be my error here? Thank you.
