[petsc-users] [External] Re: MatVec on GPUs

[Junchao Zhang]

MatSetOptionsPrefix(A,"mymat")
VecSetOptionsPrefix(v,"myvec")

--Junchao Zhang


On Mon, Oct 18, 2021 at 8:04 PM Chang Liu <cliu at pppl.gov> wrote:

> Hi Junchao,
>
> Thank you for your answer. I tried MatConvert and it works. I didn't
> make it before because I forgot to convert a vector from mpi to mpicuda
> previously.
>
> For vector, there is no VecConvert to use, so I have to do VecDuplicate,
> VecSetType and VecCopy. Is there an easier option?
>
 As Matt suggested, you could single out the matrix and vector with options
prefix and set their type on command line

MatSetOptionsPrefix(A,"mymat");
VecSetOptionsPrefix(v,"myvec");

Then, -mymat_mat_type aijcusparse -myvec_vec_type cuda

A simpler code is to have the vector type automatically set by
MatCreateVecs(A,&v,NULL)


> Chang
>
> On 10/18/21 5:23 PM, Junchao Zhang wrote:
> >
> >
> > On Mon, Oct 18, 2021 at 3:42 PM Chang Liu via petsc-users
> > <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>> wrote:
> >
> >     Hi Matt,
> >
> >     I have a related question. In my code I have many matrices and I only
> >     want to have one living on GPU, the others still staying on CPU mem.
> >
> >     I wonder if there is an easier way to copy a mpiaij matrix to
> >     mpiaijcusparse (in other words, copy data to GPUs). I can think of
> >     creating a new mpiaijcusparse matrix, and copying the data line by
> >     line.
> >     But I wonder if there is a better option.
> >
> >     I have tried MatCopy and MatConvert but neither work.
> >
> > Did you use MatConvert(mat,matype,MAT_INPLACE_MATRIX,&mat)?
> >
> >
> >     Chang
> >
> >     On 10/17/21 7:50 PM, Matthew Knepley wrote:
> >      > On Sun, Oct 17, 2021 at 7:12 PM Swarnava Ghosh
> >     <swarnava89 at gmail.com <mailto:swarnava89 at gmail.com>
> >      > <mailto:swarnava89 at gmail.com <mailto:swarnava89 at gmail.com>>>
> wrote:
> >      >
> >      >     Do I need convert the MATSEQBAIJ to a cuda matrix in code?
> >      >
> >      >
> >      > You would need a call to MatSetFromOptions() to take that type
> >     from the
> >      > command line, and not have
> >      > the type hard-coded in your application. It is generally a bad
> >     idea to
> >      > hard code the implementation type.
> >      >
> >      >     If I do it from command line, then are the other MatVec calls
> are
> >      >     ported onto CUDA? I have many MatVec calls in my code, but I
> >      >     specifically want to port just one call.
> >      >
> >      >
> >      > You can give that one matrix an options prefix to isolate it.
> >      >
> >      >    Thanks,
> >      >
> >      >       Matt
> >      >
> >      >     Sincerely,
> >      >     Swarnava
> >      >
> >      >     On Sun, Oct 17, 2021 at 7:07 PM Junchao Zhang
> >      >     <junchao.zhang at gmail.com <mailto:junchao.zhang at gmail.com>
> >     <mailto:junchao.zhang at gmail.com <mailto:junchao.zhang at gmail.com>>>
> >     wrote:
> >      >
> >      >         You can do that with command line options -mat_type
> >     aijcusparse
> >      >         -vec_type cuda
> >      >
> >      >         On Sun, Oct 17, 2021, 5:32 PM Swarnava Ghosh
> >      >         <swarnava89 at gmail.com <mailto:swarnava89 at gmail.com>
> >     <mailto:swarnava89 at gmail.com <mailto:swarnava89 at gmail.com>>> wrote:
> >      >
> >      >             Dear Petsc team,
> >      >
> >      >             I had a query regarding using CUDA to accelerate a
> matrix
> >      >             vector product.
> >      >             I have a sequential sparse matrix (MATSEQBAIJ type).
> >     I want
> >      >             to port a MatVec call onto GPUs. Is there any
> >     code/example I
> >      >             can look at?
> >      >
> >      >             Sincerely,
> >      >             SG
> >      >
> >      >
> >      >
> >      > --
> >      > What most experimenters take for granted before they begin their
> >      > experiments is infinitely more interesting than any results to
> which
> >      > their experiments lead.
> >      > -- Norbert Wiener
> >      >
> >      > https://www.cse.buffalo.edu/~knepley/
> >     <https://www.cse.buffalo.edu/~knepley/>
> >     <http://www.cse.buffalo.edu/~knepley/
> >     <http://www.cse.buffalo.edu/~knepley/>>
> >
> >     --
> >     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
>
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