[petsc-dev] [Minor issue] Lag during PetscInitialize on Fedora 36 (never seen before with other OS)

[Barry Smith]

  My guess is it related to the file system, possible caching executables and/or shared libraries. I can't see any thing in PETSc that could possible affect the start up speed based on the last time it was run.

  You can run with -info to see how quickly the output comes when you start the run.

  Barry

> On Jul 27, 2022, at 7:42 AM, LEDAC Pierre <Pierre.LEDAC at cea.fr> wrote:
> 
> Hello,
> 
> Recently migrated from Fedora34 to Fedora36, using PETSc I have some lag during the PetscInitialize, which
> disappeared if I run again immediately the binary. But after few seconds, the lag happens again (see below).
> 
> I suspected MPICH 4.0.2 on Fedora36, but a small reproducer indicated the issue is not in MPI_Init but really during PetscInitialize
> 
> Just annoying during testing, not very important, but did someone already see this ?
> 
> Thanks,
> 
> portable: /volatile/ledacp/petsc/src/ksp/ksp/tests (main) > time ./ex39
> 
> real    0m3,593s
> user    0m0,872s
> sys    0m0,433s
> portable: /volatile/ledacp/petsc/src/ksp/ksp/tests (main) > time ./ex39
> 
> real    0m0,310s
> user    0m0,884s
> sys    0m0,023s
> 
> # Wait ~20 seconds then again:
> 
> portable: /volatile/ledacp/petsc/src/ksp/ksp/tests (main) > time ./ex39
> 
> real    0m3,507s
> user    0m0,897s
> sys    0m0,025s
> portable: /volatile/ledacp/petsc/src/ksp/ksp/tests (main) > time ./ex39
> 
> real    0m0,154s
> user    0m0,725s
> sys    0m0,015s
> portable: /volatile/ledacp/petsc/src/ksp/ksp/tests (main) > time ./ex39
> 
> real    0m0,176s
> user    0m0,875s
> sys    0m0,021s
> 
> 
> Pierre LEDAC
> Commissariat à l’énergie atomique et aux énergies alternatives
> Centre de SACLAY
> DES/ISAS/DM2S/STMF/LGLS
> Bâtiment 451 – point courrier n°43
> F-91191 Gif-sur-Yvette
> +33 1 69 08 04 03
> +33 6 83 42 05 79
> <petscmachineinfo.h>

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