[petsc-users] Petsc + nvhpc

[Barry Smith]

   We recommend using PETSc 3.23.7 if you need to use the Nvidia Fortran compiler. Please try this version. If problems persist, could you send a reproducer as Junchao asked, and we will see if we can resolve the issue?

   Barry


> On Oct 16, 2025, at 12:30 PM, Junchao Zhang <junchao.zhang at gmail.com> wrote:
> 
> Hi, Herbert,
>    I don't have much experience on OpenACC and PETSc CI doesn't have such tests.  Could you avoid using nvfortran and instead use gfortran to compile your Fortran + OpenACC code?  If you, then you can use the latest petsc code and make our debugging easier. 
>    Also, could you provide us with a test and instructions to reproduce the problem?
>    
>    Thanks!
> --Junchao Zhang
> 
> 
> On Thu, Oct 16, 2025 at 5:07 AM howen via petsc-users <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>> wrote:
>> Dear All,
>> 
>> I am interfacing our CFD code (Fortran + OpenACC)  to Petsc. 
>> Since we use OpenACC the natural choice for us is to use Nvidia´s nvhpc compiler. The Gnu compiler does not work well and we do not have access to the Cray compiler.  
>> 
>> I already know that the latest version of Petsc does not compile with nvhpc, I am therefore using version 3.21.  
>> I get good results on the CPU both in serial and parallel (MPI). However, the GPU implementation, that is what we are interested in, only work correctly for the serial version. In parallel, the results are different. Even for a CG solve. 
>> 
>> I would like to know, if you have experience with the Nvidia compiler.  I am particularly interested if you have already observed issues with it. Your opinion on whether to put further effort into trying to find a bug I may have introduced during the interfacing is highly appreciated.
>> 
>> Best,
>> 
>> Herbert Owen
>> Senior Researcher, Dpt. Computer Applications in Science and Engineering
>> Barcelona Supercomputing Center (BSC-CNS)
>> Tel: +34 93 413 4038
>> Skype: herbert.owen
>> 
>> https://urldefense.us/v3/__https://scholar.google.es/citations?user=qe5O2IYAAAAJ&hl=en__;!!G_uCfscf7eWS!d2WQKdHf7ZKmQE1-LcWY1bMjyOeWcReCH2MhT18ms2AwaQcqn_NDoozxqOtBhu843jkLZI_l4XEAm8KXBAIb3AY$  <https://urldefense.us/v3/__https://scholar.google.es/citations?user=qe5O2IYAAAAJ&hl=en__;!!G_uCfscf7eWS!abuM7ozzUs7eISYBumHNxpvO2Tuy74KRM4-WWcunXHZVjQf1V032xQrCzTfC5vA_NM-35xMEZ9yJ8XK-3QFqjWBSWuUi$>
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