[petsc-dev] PetscCUDAInitialize

[Zhang, Junchao]

I saw your update. In PetscCUDAInitialize we have

      /* First get the device count */
      err   = cudaGetDeviceCount(&devCount);

      /* next determine the rank and then set the device via a mod */
      ierr   = MPI_Comm_rank(comm,&rank);CHKERRQ(ierr);
      device = rank % devCount;
    }
    err = cudaSetDevice(device);

If we rely on the first CUDA call to do initialization, how could CUDA know these MPI stuff.
--Junchao Zhang


On Wed, Sep 18, 2019 at 11:42 PM Smith, Barry F. <bsmith at mcs.anl.gov<mailto:bsmith at mcs.anl.gov>> wrote:

  Fixed the docs. Thanks for pointing out the lack of clarity


> On Sep 18, 2019, at 11:25 PM, Zhang, Junchao via petsc-dev <petsc-dev at mcs.anl.gov<mailto:petsc-dev at mcs.anl.gov>> wrote:
>
> Barry,
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> I saw you added these in init.c
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> +  -cuda_initialize - do the initialization in PetscInitialize()
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> Notes:
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>    Initializing cuBLAS takes about 1/2 second there it is done by default in PetscInitialize() before logging begins
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> But I did not get otherwise with -cuda_initialize 0, when will cuda be initialized?
> --Junchao Zhang

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