[petsc-users] [EXTERNAL] Running PETSc with a Kokkos backend on OLCF Frontier

[Barry Smith]

   We need the output when run with -log_view to see where the time is being spent and what communication between the CPU and GPU is occurring.

  Barry


> On Jun 14, 2024, at 2:59 PM, Sircar, Arpan <sircara at ornl.gov> wrote:
> 
> Hi Barry,
> 
> Thanks for your prompt response. These are run with with the same PETSc solvers but the one on GPUs (log_pKok) uses mataijkokkos while the other one does not.
> 
> Please let me know if you need any other information.
> 
> Thanks,
> Arpan
> From: Barry Smith <bsmith at petsc.dev <mailto:bsmith at petsc.dev>>
> Sent: Friday, June 14, 2024 1:47 PM
> To: Sircar, Arpan <sircara at ornl.gov <mailto:sircara at ornl.gov>>
> Cc: petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov> <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>>; Gottiparthi, Kalyan <gottiparthik at ornl.gov <mailto:gottiparthik at ornl.gov>>
> Subject: [EXTERNAL] Re: [petsc-users] Running PETSc with a Kokkos backend on OLCF Frontier
>  
> 
>    Please run both the CPU solvers and GPU solvers cases with -log_view and send the two outputs.
> 
>    Barry
> 
> 
>> On Jun 14, 2024, at 1:35 PM, Sircar, Arpan via petsc-users <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>> wrote:
>> 
>> This Message Is From an External Sender
>> This message came from outside your organization.
>> Hi,
>> 
>> We have been working with OpenFOAM (an open-source CFD software) which can transfer its matrices to PETSc to use its linear solvers. This has been tested and is working well on OCLF's Frontier machine. Next we are trying to use the Kokkos backend to run it on Frontier GPUs. While the OpenFOAM+PETSc+Kokkos environment built correctly on Frontier using the modules sourced (attached file bash_petsc4foam_gpu) and configuring PETSc correctly (attached file config_gpu), the GPU solve seems to take more time than the CPU solve.
>> 
>> The PETSc run-time options we are using are attached to this email (file fvSolution_petsc_pKok_Uof). Could you please take a look  and let us know if this combination of options is fine? In this approach we are trying to solve the pressure equation only on the GPUs.
>> 
>> Thanks,
>> Arpan
>> 
>> Arpan Sircar
>> R&D Associate Staff
>> Thermal Hydraulics Group
>> Nuclear Energy and Fuel Cycle Division
>> Oak Ridge National Laboratory
>> 
>> <fvSolution_petsc_pKok_Uof><bash_petsc4foam_gpu><config_gpu>
> 
> <log_pKok><log_pPet>

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