[petsc-dev] number of mallocs inside KSP during factorization

[Alexander Grayver]

Hello,

I use PETSs with MUMPS and looking carefully at the -ksp_view 
-ksp_monitor results I see:

KSP Object:(fwd_) 64 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:(fwd_) 64 MPI processes
   type: cholesky
     Cholesky: out-of-place factorization
     tolerance for zero pivot 2.22045e-14
     matrix ordering: natural
     factor fill ratio given 0, needed 0
       Factored matrix follows:
         Matrix Object:         64 MPI processes
           type: mpiaij
           rows=1048944, cols=1048944
           package used to perform factorization: mumps
           total: nonzeros=1266866685, allocated nonzeros=1266866685
           total number of mallocs used during MatSetValues calls =0
             MUMPS run parameters:
               SYM (matrix type):                   1
               PAR (host participation):            1
               ICNTL(1) (output for error):         6
               ICNTL(2) (output of diagnostic msg): 0
               ICNTL(3) (output for global info):   0
               ICNTL(4) (level of printing):        0
               ICNTL(5) (input mat struct):         0
               ICNTL(6) (matrix prescaling):        0
               ICNTL(7) (sequentia matrix ordering):5
               ICNTL(8) (scalling strategy):        77
               ICNTL(10) (max num of refinements):  0
               ICNTL(11) (error analysis):          0
               ICNTL(12) (efficiency control):                         1
               ICNTL(13) (efficiency control):                         0
               ICNTL(14) (percentage of estimated workspace increase): 30
               ICNTL(18) (input mat struct):                           3
               ICNTL(19) (Shur complement info):                       0
               ICNTL(20) (rhs sparse pattern):                         0
               ICNTL(21) (solution struct):                            1
               ICNTL(22) (in-core/out-of-core facility):               0
               ICNTL(23) (max size of memory can be allocated locally):0
               ICNTL(24) (detection of null pivot rows):               0
               ICNTL(25) (computation of a null space basis):          0
               ICNTL(26) (Schur options for rhs or solution):          0
               ICNTL(27) (experimental parameter):                     -8
               ICNTL(28) (use parallel or sequential ordering):        2
               ICNTL(29) (parallel ordering):                          0
               ICNTL(30) (user-specified set of entries in inv(A)):    0
               ICNTL(31) (factors is discarded in the solve phase):    0
               ICNTL(33) (compute determinant):                        0
               ...
   linear system matrix = precond matrix:
   Matrix Object:   64 MPI processes
     type: mpiaij
     rows=1048944, cols=1048944
*    total: nonzeros=7251312, allocated nonzeros=11554449
     total number of mallocs used during MatSetValues calls =1071*
       not using I-node (on process 0) routines

The particularly interesting part are last 3 lines.
Where do these mallocs come from? Is it possible to reduce this number?

Regards,
Alexander

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