Ok, I ll try jacobi. I am also testing MHD cases by the way (interaction of Solar wind and earth Magnetosphere, both steady and unsteady) :-) Thx Andrea
On May 6, 2013, at 7:17 PM, "Nystrom, William D" <wdn at lanl.gov> wrote: > Andrea, > > Have you tried jacobi preconditioning with gpus. I've found it to work pretty > well, surprisingly, and it does work in parallel with mpi. It is also worth > seeing > if you can use the ell or hyb matrix formats. I have seen a reduction in > compute > time using ell/hyb matrix formats of typically 2x up to as much as 5x when the > iteration counts get large. You should also try both the cusp and cusparse > mat_type. I've tried the above on extended mhd problems. YMMV. > > Having said that, I am looking forward to trying better preconditioners for > gpus > as they become available. But it would be interesting to see if jacobi > preconditioning > on the gpu solves your problem faster than your best preconditioning option on > the cpu. Also, all my problems have been SPD. > > Dave > > -- > Dave Nystrom > LANL HPC-5 > Phone: 505-667-7913 > Email: wdn at lanl.gov > Smail: Mail Stop B272 > Group HPC-5 > Los Alamos National Laboratory > Los Alamos, NM 87545 > > From: petsc-dev-bounces at mcs.anl.gov [petsc-dev-bounces at mcs.anl.gov] on > behalf of Andrea Lani [andrea.lani at gmail.com] > Sent: Monday, May 06, 2013 10:52 AM > To: Paul Mullowney > Cc: petsc-dev at mcs.anl.gov > Subject: Re: [petsc-dev] Preconditioners for GPU > > Thanks Paul! this only work for sequential cases, right? in this case, what > performance benefit should I expect compared to a fully CPU-based version, if > any? is anything available also for parallel runs? > > Andrea > > > On Mon, May 6, 2013 at 5:48 PM, Paul Mullowney <paulm at txcorp.com> wrote: > Hi Andrea, > > The matrix type, aijcusparse has an ILU(n) (and ICC(n) for symmetric > problems) preconditioner. The factorization is done on the CPU. The solves > are done on the GPU via the cusparse library. > > In the configure, do --download-txpetscgpu=yes > > I would also look at: > > http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/Mat/MATSEQAIJCUSPARSE.html > > for information on the aijcusparse class. > > -Paul > > >> On Sun, May 5, 2013 at 4:26 PM, Andrea Lani <andrea.lani at gmail.com> wrote: >> Thanks, Matt! Let me re-iterate on the question... are there other available >> preconditioners already ported to GPU, which are not based on AMG (which is >> typically not suitable for my convection-dominated CFD problems) and apart >> from BICGSTABCUSP? >> >> I believe that the txpetscgpu package has triangular solves for the GPU. >> >> BiCGStab is a Krylov method. >> >> Matt >> >> Andrea >> >> >> On May 5, 2013, at 9:53 PM, Matthew Knepley <knepley at gmail.com> wrote: >> >>> On Sun, May 5, 2013 at 2:48 PM, Andrea Lani <andrea.lani at gmail.com> >>> wrote: >>> Dear Developers, >>> >>> Could you please tell me the list of preconditioners for non-symmetric >>> systems fully ported to multi-GPU and available in the current development >>> version? >>> >>> In my opinion, there are no truly multi-GPU preconditioners anywhere. We >>> can imagine them, like AMG with Chebychev smoothers, but >>> I have not really seen any of them reliably work. The CUSP SA-AMG is the >>> closest one in this category, and Steve Dalton is working on >>> it this summer at ANL. >>> >>> Matt >>> >>> Thanks in advance >>> >>> Andrea >>> >>> >>> >>> -- >>> 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 >> >> >> >> -- >> 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 > > > > > -- > Dr. Andrea Lani > Senior Research Engineer, PhD > Aeronautics & Aerospace dept., CFD group > Von Karman Institute for Fluid Dynamics > Chausse de Waterloo 72, > B-1640, Rhode-Saint-Genese, Belgium > fax : +32-2-3599600 > work : +32-2-3599769 > lani at vki.ac.be -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20130506/86669c53/attachment-0001.html>
