venkatesh: > On Tue, May 26, 2015 at 9:02 PM, Hong <[email protected]> wrote: > >> 'A serial job in MATLAB for the same matrices takes < 60GB. ' >> Can you run this case in serial? If so, try petsc, superlu or mumps to >> make sure the matrix is non-singular. >> > B matrix is singular but I get my result in Petsc and Mumps for small > matrices. >
You are lucky to get something out of a singular matrix using LU factorization, likely due to arithmetic roundoff. Is the obtained solution useful? Suggest reading petsc or slepc manual on how to dump out null space when a matrix is singular. Hong > >> Both mumps and superlu_dist show crash in MatFactorNumeric(). Mumps gives >> error >> [16]PETSC ERROR: Error reported by MUMPS in numerical factorization >> phase: Cannot allocate required memory 65710 megabytes. >> >> Does your code work for smaller problems? >> > Yes code works for small problems > >> Try using more processors? >> >> Why use such huge '-mat_mumps_icntl_14 200000' (percentage of estimated >> workspace increase)? The default is 20. Try 40? >> >> Superlu_dist usually uses less memory than mumps, but it also crashes. I >> guess something wrong with your matrix. Is it singular? >> > The B matrix is singular. So Super Lu cant be used is it ? > > >> Run superlu_dist on a slightly smaller matrix with option >> '-mat_superlu_dist_statprint' which displays memory usage info., e.g., >> > Ok I will do that and check. > >> petsc/src/ksp/ksp/examples/tutorials (maint) >> $ mpiexec -n 2 ./ex2 -pc_type lu -pc_factor_mat_solver_package >> superlu_dist -mat_superlu_dist_statprint >> Nonzeros in L 560 >> Nonzeros in U 560 >> nonzeros in L+U 1064 >> nonzeros in LSUB 248 >> NUMfact space (MB) sum(procs): L\U 0.01 all 0.05 >> Total highmark (MB): All 0.05 Avg 0.02 Max 0.02 >> EQUIL time 0.00 >> ROWPERM time 0.00 >> COLPERM time 0.00 >> SYMBFACT time 0.00 >> DISTRIBUTE time 0.00 >> FACTOR time 0.00 >> Factor flops 1.181000e+04 Mflops 4.80 >> SOLVE time 0.00 >> SOLVE time 0.00 >> Solve flops 2.194000e+03 Mflops 4.43 >> SOLVE time 0.00 >> Solve flops 2.194000e+03 Mflops 5.14 >> Norm of error 1.18018e-15 iterations 1 >> >> Hong >> >> >> On Tue, May 26, 2015 at 9:03 AM, venkatesh g <[email protected]> >> wrote: >> >>> I posted a while ago in MUMPS forums but no one seems to reply. >>> >>> I am solving a large generalized Eigenvalue problem. >>> >>> I am getting the following error which is attached, after giving the >>> command: >>> >>> /cluster/share/venkatesh/petsc-3.5.3/linux-gnu/bin/mpiexec -np 64 -hosts >>> compute-0-4,compute-0-6,compute-0-7,compute-0-8 ./ex7 -f1 a72t -f2 b72t >>> -st_type sinvert -eps_nev 3 -eps_target 0.5 -st_ksp_type preonly >>> -st_pc_type lu -st_pc_factor_mat_solver_package mumps -mat_mumps_icntl_14 >>> 200000 >>> >>> IT IS impossible to allocate so much memory per processor.. it is asking >>> like around 70 GB per processor. >>> >>> A serial job in MATLAB for the same matrices takes < 60GB. >>> >>> After trying out superLU_dist, I have attached the error there also >>> (segmentation error). >>> >>> Kindly help me. >>> >>> Venkatesh >>> >>> >>> >> >
