[petsc-users] MatCopy and MatSetValue consume most 99 percentage of runtime

[Debao Shao]

Hi, Barry:

Thanks for the reply.

I preallocated enough space for the sparse matrix, but I found mat->data->imax changed after "MatAssemblyEnd", and it caused many rowmax less than the number of nonzeros per row, then "MatSeqXAIJReallocateAIJ" is called frequently when doing MatSetValues again to the matrix.

Any suggestions?

Thanks,
Debao
-----Original Message-----
From: petsc-users-bounces at mcs.anl.gov [mailto:petsc-users-bounces at mcs.anl.gov] On Behalf Of Barry Smith
Sent: Friday, April 15, 2011 9:25 PM
To: PETSc users list
Subject: Re: [petsc-users] MatCopy and MatSetValue consume most 99 percentage of runtime


   Debao,

      Please see http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#efficient-assembly It should resolve the difficulties.

    Barry

On Apr 15, 2011, at 2:16 AM, Debao Shao wrote:

> Dear Petsc:
>
> I'm trying on Petsc iterative solver(KSPCG & PCJACOBI), but it's strange that the two functions "MatCopy" and "MatSetValue" consume most of runtime, and the functions were not called frequently, just several times.
>
> My libpetsc.a is built as follows:
> 1, /config/configure.py --with-mpi=0 --with-debugging=0 -with-log=0 -with-info=0
> 2, make all;
>
> It's very appreciated to get your reply.
>
> Thanks a lot,
> Debao
>
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