[petsc-users] PETSC using 32-bit integers

[Smith, Barry F.]

  Yes, you need to build a new PETSC_ARCH for 32 with optimization turned on. 

export PETSC_ARCH=arch-something-appropriate
./configure --with-debugging=0 all the options you previously used

Barry


> On Jun 25, 2019, at 7:20 AM, José Lorenzo via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> Matthew,
> 
> thank you for your useful advice. By running the code with -log_view I have found the following message which might be related to my performance troubles and that only appears when using PETSC with 32 bit integers:
> 
>       ##########################################################
>       #                                                        #
>       #                       WARNING!!!                       #
>       #                                                        #
>       #   This code was compiled with a debugging option.      #
>       #   To get timing results run ./configure                #
>       #   using --with-debugging=no, the performance will      #
>       #   be generally two or three times faster.              #
>       #                                                        #
>       ##########################################################
> 
> 
> 
> El mar., 25 jun. 2019 a las 12:32, Matthew Knepley (<knepley at gmail.com>) escribió:
> For any performance question, we need to see the output of -log_view for each case compared.
> 
>   Thanks,
> 
>     Matt
> 
> On Tue, Jun 25, 2019 at 5:55 AM José Lorenzo via petsc-users <petsc-users at mcs.anl.gov> wrote:
> I have access to two PETSC installations: one using 64-bit integers and another one with 32-bit integers. For some reason, when I run the exactly same FORTRAN code (except for the size of integer type) using both installations, the 32-bit one exhibits much lower performance in terms of computation time. This is a problem because I need the 32-bit version in order to be able to use the LU factorization provided in MUMPS.
> 
> I would appreciate any hint helping me understand why this may happen.
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> https://www.cse.buffalo.edu/~knepley/