[petsc-users] [External] Re: request to add an option similar to use_omp_threads for mumps to cusparse solver

[Chang Liu]

Hi Junchao,

No I only needs it to be transferred within a node. I use block-Jacobi 
method and GMRES to solve the sparse matrix, so each direct solver will 
take care of a sub-block of the whole matrix. In this way, I can use one 
GPU to solve one sub-block, which is stored within one node.

It was stated in the documentation that cusparse solver is slow. 
However, in my test using ex72.c, the cusparse solver is faster than 
mumps or superlu_dist on CPUs.

Chang

On 10/12/21 10:24 AM, Junchao Zhang wrote:
> Hi, Chang,
>     For the mumps solver, we usually transfers matrix and vector data 
> within a compute node.  For the idea you propose, it looks like we need 
> to gather data within MPI_COMM_WORLD, right?
> 
>     Mark, I remember you said cusparse solve is slow and you would 
> rather do it on CPU. Is it right?
> 
> --Junchao Zhang
> 
> 
> On Mon, Oct 11, 2021 at 10:25 PM Chang Liu via petsc-users 
> <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>> wrote:
> 
>     Hi,
> 
>     Currently, it is possible to use mumps solver in PETSC with
>     -mat_mumps_use_omp_threads option, so that multiple MPI processes will
>     transfer the matrix and rhs data to the master rank, and then master
>     rank will call mumps with OpenMP to solve the matrix.
> 
>     I wonder if someone can develop similar option for cusparse solver.
>     Right now, this solver does not work with mpiaijcusparse. I think a
>     possible workaround is to transfer all the matrix data to one MPI
>     process, and then upload the data to GPU to solve. In this way, one can
>     use cusparse solver for a MPI program.
> 
>     Chang
>     -- 
>     Chang Liu
>     Staff Research Physicist
>     +1 609 243 3438
>     cliu at pppl.gov <mailto:cliu at pppl.gov>
>     Princeton Plasma Physics Laboratory
>     100 Stellarator Rd, Princeton NJ 08540, USA
> 

-- 
Chang Liu
Staff Research Physicist
+1 609 243 3438
cliu at pppl.gov
Princeton Plasma Physics Laboratory
100 Stellarator Rd, Princeton NJ 08540, USA