You have my condolences if you have to support all those things simultaneously.
On Wed, Jan 4, 2023, 7:27 PM Matthew Knepley <[email protected]> wrote: > On Wed, Jan 4, 2023 at 7:22 PM Junchao Zhang <[email protected]> > wrote: > >> We don't have a machine for us to test with both "--with-cuda --with-hip" >> > > Yes, but your answer suggested that the structure of the code prevented > this combination. > > Thanks, > > Matt > > >> --Junchao Zhang >> >> >> On Wed, Jan 4, 2023 at 6:17 PM Matthew Knepley <[email protected]> wrote: >> >>> On Wed, Jan 4, 2023 at 7:09 PM Junchao Zhang <[email protected]> >>> wrote: >>> >>>> On Wed, Jan 4, 2023 at 6:02 PM Matthew Knepley <[email protected]> >>>> wrote: >>>> >>>>> On Wed, Jan 4, 2023 at 6:49 PM Junchao Zhang <[email protected]> >>>>> wrote: >>>>> >>>>>> >>>>>> On Wed, Jan 4, 2023 at 5:40 PM Mark Lohry <[email protected]> wrote: >>>>>> >>>>>>> Oh, is the device backend not known at compile time? >>>>>>> >>>>>> Currently it is known at compile time. >>>>>> >>>>> >>>>> Are you sure? I don't think it is known at compile time. >>>>> >>>> We define either PETSC_HAVE_CUDA or PETSC_HAVE_HIP or NONE, but not >>>> both >>>> >>> >>> Where is the logic for that in the code? This seems like a crazy design. >>> >>> Thanks, >>> >>> Matt >>> >>> >>>> Thanks, >>>>> >>>>> Matt >>>>> >>>>> >>>>>> Or multiple backends can be alive at once? >>>>>>> >>>>>> >>>>>> Some petsc developers (Jed and Barry) want to support this, but we >>>>>> are incapable now. >>>>>> >>>>>> >>>>>>> >>>>>>> On Wed, Jan 4, 2023, 6:27 PM Junchao Zhang <[email protected]> >>>>>>> wrote: >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Wed, Jan 4, 2023 at 5:19 PM Mark Lohry <[email protected]> wrote: >>>>>>>> >>>>>>>>> Maybe we could add a MatCreateSeqAIJCUSPARSEWithArrays(), but then >>>>>>>>>> we would need another for MATMPIAIJCUSPARSE, and then for HIPSPARSE >>>>>>>>>> on AMD >>>>>>>>>> GPUs, ... >>>>>>>>> >>>>>>>>> >>>>>>>>> Wouldn't one function suffice? Assuming these are contiguous >>>>>>>>> arrays in CSR format, they're just raw device pointers in all cases. >>>>>>>>> >>>>>>>> But we need to know what device it is (to dispatch to either >>>>>>>> petsc-CUDA or petsc-HIP backend) >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> On Wed, Jan 4, 2023 at 6:02 PM Junchao Zhang < >>>>>>>>> [email protected]> wrote: >>>>>>>>> >>>>>>>>>> No, we don't have a counterpart of MatCreateSeqAIJWithArrays() >>>>>>>>>> for GPUs. Maybe we could add a MatCreateSeqAIJCUSPARSEWithArrays(), >>>>>>>>>> but >>>>>>>>>> then we would need another for MATMPIAIJCUSPARSE, and then for >>>>>>>>>> HIPSPARSE on >>>>>>>>>> AMD GPUs, ... >>>>>>>>>> >>>>>>>>>> The real problem I think is to deal with multiple MPI ranks. >>>>>>>>>> Providing the split arrays for petsc MATMPIAIJ is not easy and thus >>>>>>>>>> is >>>>>>>>>> discouraged for users to do so. >>>>>>>>>> >>>>>>>>>> A workaround is to let petsc build the matrix and allocate the >>>>>>>>>> memory, then you call MatSeqAIJCUSPARSEGetArray() to get the array >>>>>>>>>> and fill >>>>>>>>>> it up. >>>>>>>>>> >>>>>>>>>> We recently added routines to support matrix assembly on GPUs, >>>>>>>>>> see if MatSetValuesCOO >>>>>>>>>> <https://petsc.org/release/docs/manualpages/Mat/MatSetValuesCOO/> >>>>>>>>>> helps >>>>>>>>>> >>>>>>>>>> --Junchao Zhang >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Wed, Jan 4, 2023 at 2:22 PM Mark Lohry <[email protected]> >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> I have a sparse matrix constructed in non-petsc code using a >>>>>>>>>>> standard CSR representation where I compute the Jacobian to be used >>>>>>>>>>> in an >>>>>>>>>>> implicit TS context. In the CPU world I call >>>>>>>>>>> >>>>>>>>>>> MatCreateSeqAIJWithArrays(PETSC_COMM_WORLD, nrows, ncols, >>>>>>>>>>> rowidxptr, colidxptr, valptr, Jac); >>>>>>>>>>> >>>>>>>>>>> which as I understand it -- (1) never copies/allocates that >>>>>>>>>>> information, and the matrix Jac is just a non-owning view into the >>>>>>>>>>> already >>>>>>>>>>> allocated CSR, (2) I can write directly into the original data >>>>>>>>>>> structures >>>>>>>>>>> and the Mat just "knows" about it, although it still needs a call to >>>>>>>>>>> MatAssemblyBegin/MatAssemblyEnd after modifying the values. So far >>>>>>>>>>> this >>>>>>>>>>> works great with GAMG. >>>>>>>>>>> >>>>>>>>>>> I have the same CSR representation filled in GPU data allocated >>>>>>>>>>> with cudaMalloc and filled on-device. Is there an equivalent Mat >>>>>>>>>>> constructor for GPU arrays, or some other way to avoid unnecessary >>>>>>>>>>> copies? >>>>>>>>>>> >>>>>>>>>>> Thanks, >>>>>>>>>>> Mark >>>>>>>>>>> >>>>>>>>>> >>>>> >>>>> -- >>>>> 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/ >>>>> <http://www.cse.buffalo.edu/~knepley/> >>>>> >>>> >>> >>> -- >>> 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/ >>> <http://www.cse.buffalo.edu/~knepley/> >>> >> > > -- > 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/ > <http://www.cse.buffalo.edu/~knepley/> >
