On May 2, 2014, at 5:29 PM, Song Gao <[email protected]> wrote:
> Thanks for your quick reply. What confused me is that why would the code > works fine if I reset the gmres restart number by recalling > kspgmressetrestart just before kspsolve? It isn’t really working. Something is going wrong (run with valgrind) and setting that restart number and starting the solver just puts it in a “happier” state so it seems to make more progress. Barry > > Sent from my iPhone > >> On May 2, 2014, at 6:03 PM, "Barry Smith" <[email protected]> wrote: >> >> >> 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. >>
