[petsc-users] PETSc MPI world question

[Junchao Zhang]

Hi Joseph,
  You can assign your compute world to PETSC_COMM_WORLD, see details at
https://urldefense.us/v3/__https://petsc.org/release/manualpages/Sys/PETSC_COMM_WORLD/__;!!G_uCfscf7eWS!dDxJM3yq12GVC1XnZzMj7RWxqbiL2tvNVy9uKv7CjDP-Z8XI1haKNkutdS3cZtVpl4pU-Ib_Q82ppfhYWkx28FC0aRvp$ 

--Junchao Zhang


On Fri, May 29, 2026 at 10:06 AM Y. Joseph Zhang via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Hi:
>
> We've been using PETSc solvers in our code for many years. A few years ago
> we changed the I/O method to improve efficiency, by reserving dedicated
> 'scribe' MPI processes. This entails the partitioning of MPI_COMM_WORLD
> into 2 worlds (1 for compute and the other for I/O).
>
> Is there a way to ask PETSc to use compute world only? Otherwise we'd get
> a lot of errors.
>
> Thank you for the great tool for the community!
>
>
>
> -Joseph
>
>
>
> Joseph Zhang
>
> Office: (804) 684 7464
>
> Web: schism.wiki
>
>
>
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