[petsc-users] [External] Re: MatVec on GPUs
Junchao Zhang
junchao.zhang at gmail.com
Wed Oct 20 19:24:53 CDT 2021
Hi, Chang,
Do you have the error stack message? And yes, petsc gpu code is tricky,
since we have to carefully sync data on GPU and CPU.
Thanks.
On Wed, Oct 20, 2021 at 11:55 AM Chang Liu <cliu at pppl.gov> wrote:
> Hi Junchao,
>
> Thank you for the suggestion. I did some more tests and found that
> MatConvert does not always work. In one of my tests, I did MatConvert to
> convert the matrix to aijcusparse, then did a preonly ksp solver and it
> works well. But then I tried a fgmres solver and it gave an error. It
> only happen when the matrix is mpiaijcusparse and for seqaijcusparse it
> works.
>
> So I tried to create a new aijcusparse matrix and copy the data line by
> line, then both solvers works. So I guess there are some tricky things
> with MatConvert.
>
> Chang
>
> On 10/18/21 9:23 PM, Junchao Zhang wrote:
> > MatSetOptionsPrefix(A,"mymat")
> > VecSetOptionsPrefix(v,"myvec")
> >
> > --Junchao Zhang
> >
> >
> > On Mon, Oct 18, 2021 at 8:04 PM Chang Liu <cliu at pppl.gov
> > <mailto: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>
> > <mailto: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>>
> > > > <mailto: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>>
> > > <mailto: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>>
> > > <mailto: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/>
> > > <https://www.cse.buffalo.edu/~knepley/
> > <https://www.cse.buffalo.edu/~knepley/>>
> > > <http://www.cse.buffalo.edu/~knepley/
> > <http://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> <mailto: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 <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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