[petsc-users] Using PETSc GPU backend

[Ng, Cho-Kuen]

Paul,

Thank you for your suggestion. I will try different spack install specifications.

Cho
________________________________
From: Grosse-Bley, Paul Leonard <paul.grosse-bley at stud.uni-heidelberg.de>
Sent: Friday, June 30, 2023 4:07 AM
To: Ng, Cho-Kuen <cho at slac.stanford.edu>
Cc: petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>
Subject: Re: [petsc-users] Using PETSc GPU backend

Hi Cho,

you might want to specify the GPU architecture to make sure that everything is compiled optimally.
I.e. "spack install petsc +cuda cuda_arch=80 +zoltan"

Best,
Paul


On Friday, June 30, 2023 01:50 CEST, petsc-users-request at mcs.anl.gov wrote:

Date: Thu, 29 Jun 2023 23:50:10 +0000
From: "Ng, Cho-Kuen" <cho at slac.stanford.edu>
To: "petsc-users at mcs.anl.gov" <petsc-users at mcs.anl.gov>
Subject: [petsc-users] Using PETSc GPU backend
Message-ID:
<BYAPR07MB5431A3DACC91A963572D66E4E025A at BYAPR07MB5431.namprd07.prod.outlook.com>

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I installed PETSc on Perlmutter using "spack install petsc+cuda+zoltan" and used it by "spack load petsc/fwge6pf". Then I compiled the application code (purely CPU code) linking to the petsc package, hoping that I can get performance improvement using the petsc GPU backend. However, the timing was the same using the same number of MPI tasks with and without GPU accelerators. Have I missed something in the process, for example, setting up PETSc options at runtime to use the GPU backend?

Thanks,
Cho
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