Some subroutine in PETSc is a little slow

[Barry Smith]

http://www-unix.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#slow


On Sep 21, 2008, at 2:22 PM, Chen, Changjun wrote:

> Dear Sir,
>      I have be using PETSc for many days. Recently I find one  
> subroutine in PETSc is a little slow, It is an initialization  
> subroutine to fill in the matrix elements:
>
>     call MatSetValues(A,ione,II,ione,JJ,v,INSERT_VALUES,ierr)
>
>      I find that the total time to fill in the matrix data is even  
> much longer than the iteration time to solve the system
>               call KSPSolve(ksp,b,x,ierr)
>      How could this happen?  Could I accelerate the time for filling  
> in the data?
>
> Sincerely,
> Changjun Chen
>