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.le...@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>
