Are you thinking CUDA Fortran or some other "Fortran but running on the GPU"?
> On Dec 12, 2023, at 8:11 PM, Jed Brown <j...@jedbrown.org> wrote: > > Han Tran <hant...@cs.utah.edu> writes: > >> Hi Jed, >> >> Thank you for your answer. I have not had a chance to work on this since I >> asked. I have some follow-up questions. >> >> (1) From the Petsc manual, >> https://petsc.org/release/manualpages/Vec/VecGetArrayAndMemType/, it shows >> that both VecGetArrayAndMemType() and VecGetArrayReadAndMemType() do not >> have Fortran support. Has Petsc added the Fortran support for these >> functions so far? > > It doesn't look like it. I think one would mirror the VecGetArrayF90 > implementation. > >> (2) My user-defined MatMult(A, u, v) already handles the communication, >> i.e., the return vector v=A*u was computed with all needed communication. >> Thus, I do not quite understand when you said that “use >> DMGlobalToLocalBegin/End()…”. Do I need this function even if the >> communication is already done by my user-defined MatMult()? > > If you do your own communication, you don't need to use > DMGlobalToLocalBegin/End. > >> >> Thank you, >> Han >> >>> On Nov 4, 2022, at 9:06 AM, Jed Brown <j...@jedbrown.org> wrote: >>> >>> Yes, this is supported. You can use VecGetArrayAndMemType() to get access >>> to device memory. You'll often use DMGlobalToLocalBegin/End() or VecScatter >>> to communicate, but that will use GPU-aware MPI if your Vec is a device >>> vector. >>> >>> Han Tran <hant...@cs.utah.edu> writes: >>> >>>> Hi, >>>> >>>> I am aware that PETSc recently supports solvers on GPU. I wonder whether >>>> PETSc supports MatShell with GPU solvers, i.e., I have a user-defined >>>> MatMult() function residing on the device, and I want to use MatShell >>>> directly with PETSc GPU solvers without any transfer back and forth >>>> between host and device. If this is possible, could you let me know how to >>>> do this (an example, if any, would be very appreciated)? >>>> >>>> Thank you! >>>> Han
