Dear Barry, you are right. The Cray argument checking is incorrect. It does work with download-fblaslapack. However it does fail to converge. Is there anything obviously wrong with my petscrc? Anything else am I missing?
Thanks Il giorno gio 13 ago 2020 alle ore 03:17 Barry Smith <bsm...@petsc.dev> ha scritto: > > The QR is always done on the CPU, we don't have generic calls to > blas/lapack go to the GPU currently. > > The error message is: > > On entry to __cray_mgm_dgeqrf, parameter 7 had an illegal value (info = > -7) > > argument 7 is &LWORK which is defined by > > PetscBLASInt LWORK=N*bs; > > and > > N=nSAvec is the column block size of new P. > > Presumably this is a huge run with many processes so using the debugger > is not practical? > > We need to see what these variables are > > N, bs, nSAvec > > perhaps nSAvec is zero which could easily upset LAPACK. > > Crudest thing would be to just put a print statement in the code > before the LAPACK call of if they are called many times add an error check > like that > generates an error if any of these three values are 0 (or negative). > > Barry > > > It is not impossible that the Cray argument checking is incorrect and > the value passed in is fine. You can check this by using > --download-fblaslapack and see if the same or some other error comes up. > > > > > > > > > On Aug 12, 2020, at 7:19 PM, Mark Adams <mfad...@lbl.gov> wrote: > > Can you reproduce this on the CPU? > The QR factorization seems to be failing. That could be from bad data or a > bad GPU QR. > > On Wed, Aug 12, 2020 at 4:19 AM nicola varini <nicola.var...@gmail.com> > wrote: > >> Dear all, following the suggestions I did resubmit the simulation with >> the petscrc below. >> However I do get the following error: >> ======== >> 7362 [592]PETSC ERROR: #1 formProl0() line 748 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/agg.c >> 7363 [339]PETSC ERROR: Petsc has generated inconsistent data >> 7364 [339]PETSC ERROR: xGEQRF error >> 7365 [339]PETSC ERROR: See >> https://www.mcs.anl.gov/petsc/documentation/faq.html for trouble >> shooting. >> 7366 [339]PETSC ERROR: Petsc Release Version 3.13.3, Jul 01, 2020 >> 7367 [339]PETSC ERROR: >> /users/nvarini/gbs_test_nicola/bin/gbs_daint_gpu_gnu on a named nid05083 >> by nvarini Wed Aug 12 10:06:15 2020 >> 7368 [339]PETSC ERROR: Configure options --with-cc=cc --with-fc=ftn >> --known-mpi-shared-libraries=1 --known-mpi-c-double-complex=1 >> --known-mpi-int64_t=1 --known-mpi-long-double=1 --with-batch=1 >> --known-64-bit-blas-indices=0 --LIBS=-lstdc++ --with-cxxlib-autodetect=0 >> --with-scalapa ck=1 --with-cxx=CC --with-debugging=0 >> --with-hypre-dir=/opt/cray/pe/tpsl/19.06.1/GNU/8.2/haswell >> --prefix=/scratch/snx3000/nvarini/petsc3.13.3-gpu --with-cuda=1 >> --with-cuda-c=nvcc --with-cxxlib-autodetect=0 >> --COPTFLAGS=-I/opt/cray/pe/mpt/7.7.10/gni/mpich-intel/16.0/include - >> -with-cxx=CC >> --CXXOPTFLAGS=-I/opt/cray/pe/mpt/7.7.10/gni/mpich-intel/16.0/include >> 7369 [592]PETSC ERROR: #2 PCGAMGProlongator_AGG() line 1063 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/agg.c >> 7370 [592]PETSC ERROR: #3 PCSetUp_GAMG() line 548 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/gamg.c >> 7371 [592]PETSC ERROR: #4 PCSetUp() line 898 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/interface/precon.c >> 7372 [592]PETSC ERROR: #5 KSPSetUp() line 376 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/ksp/interface/itfunc.c >> 7373 [592]PETSC ERROR: #6 KSPSolve_Private() line 633 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/ksp/interface/itfunc.c >> 7374 [316]PETSC ERROR: #3 PCSetUp_GAMG() line 548 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/gamg.c >> 7375 [339]PETSC ERROR: #1 formProl0() line 748 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/agg.c >> 7376 [339]PETSC ERROR: #2 PCGAMGProlongator_AGG() line 1063 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/agg.c >> 7377 [339]PETSC ERROR: #3 PCSetUp_GAMG() line 548 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/gamg.c >> 7378 [339]PETSC ERROR: #4 PCSetUp() line 898 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/interface/precon.c >> 7379 [339]PETSC ERROR: #5 KSPSetUp() line 376 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/ksp/interface/itfunc.c >> 7380 [592]PETSC ERROR: #7 KSPSolve() line 853 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/ksp/interface/itfunc.c >> 7381 [339]PETSC ERROR: #6 KSPSolve_Private() line 633 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/ksp/interface/itfunc.c >> 7382 [339]PETSC ERROR: #7 KSPSolve() line 853 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/ksp/interface/itfunc.c >> 7383 On entry to __cray_mgm_dgeqrf, parameter 7 had an illegal value >> (info = -7) >> 7384 [160]PETSC ERROR: #3 PCSetUp_GAMG() line 548 in >> /scratch/snx3000/nvarini/petsc-3.13.3/src/ksp/pc/impls/gamg/gamg.c >> ======== >> >> I did try other pc_gamg_type but they fails as well. >> >> >> #PETSc Option Table entries: >> -ampere_dm_mat_type aijcusparse >> -ampere_dm_vec_type cuda >> -ampere_ksp_atol 1e-15 >> -ampere_ksp_initial_guess_nonzero yes >> -ampere_ksp_reuse_preconditioner yes >> -ampere_ksp_rtol 1e-7 >> -ampere_ksp_type dgmres >> -ampere_mg_levels_esteig_ksp_max_it 10 >> -ampere_mg_levels_esteig_ksp_type cg >> -ampere_mg_levels_ksp_chebyshev_esteig 0,0.05,0,1.05 >> -ampere_mg_levels_ksp_type chebyshev >> -ampere_mg_levels_pc_type jacobi >> -ampere_pc_gamg_agg_nsmooths 1 >> -ampere_pc_gamg_coarse_eq_limit 10 >> -ampere_pc_gamg_reuse_interpolation true >> -ampere_pc_gamg_square_graph 1 >> -ampere_pc_gamg_threshold 0.05 >> -ampere_pc_gamg_threshold_scale .0 >> -ampere_pc_gamg_type agg >> -ampere_pc_type gamg >> -dm_mat_type aijcusparse >> -dm_vec_type cuda >> -log_view >> -poisson_dm_mat_type aijcusparse >> -poisson_dm_vec_type cuda >> -poisson_ksp_atol 1e-15 >> -poisson_ksp_initial_guess_nonzero yes >> -poisson_ksp_reuse_preconditioner yes >> -poisson_ksp_rtol 1e-7 >> -poisson_ksp_type dgmres >> -poisson_log_view >> -poisson_mg_levels_esteig_ksp_max_it 10 >> -poisson_mg_levels_esteig_ksp_type cg >> -poisson_mg_levels_ksp_chebyshev_esteig 0,0.05,0,1.05 >> -poisson_mg_levels_ksp_max_it 1 >> -poisson_mg_levels_ksp_type chebyshev >> -poisson_mg_levels_pc_type jacobi >> -poisson_pc_gamg_agg_nsmooths 1 >> -poisson_pc_gamg_coarse_eq_limit 10 >> -poisson_pc_gamg_reuse_interpolation true >> -poisson_pc_gamg_square_graph 1 >> -poisson_pc_gamg_threshold 0.05 >> -poisson_pc_gamg_threshold_scale .0 >> -poisson_pc_gamg_type agg >> -poisson_pc_type gamg >> -use_mat_nearnullspace true >> #End of PETSc Option Table entries >> >> Regards, >> >> Nicola >> >> Il giorno mar 4 ago 2020 alle ore 17:57 Mark Adams <mfad...@lbl.gov> ha >> scritto: >> >>> >>> >>> On Tue, Aug 4, 2020 at 6:35 AM Stefano Zampini < >>> stefano.zamp...@gmail.com> wrote: >>> >>>> Nicola, >>>> >>>> You are actually not using the GPU properly, since you use HYPRE >>>> preconditioning, which is CPU only. One of your solvers is actually slower >>>> on “GPU”. >>>> For a full AMG GPU, you can use PCGAMG, with cheby smoothers and with >>>> Jacobi preconditioning. Mark can help you out with the specific command >>>> line options. >>>> When it works properly, everything related to PC application is >>>> offloaded to the GPU, and you should expect to get the well-known and >>>> branded 10x (maybe more) speedup one is expecting from GPUs during KSPSolve >>>> >>>> >>> The speedup depends on the machine, but on SUMMIT, using enough CPUs to >>> saturate the memory bus vs all 6 GPUs the speedup is a function of problem >>> subdomain size. I saw 10x at about 100K equations/process. >>> >>> >>>> Doing what you want to do is one of the last optimization steps of an >>>> already optimized code before entering production. Yours is not even >>>> optimized for proper GPU usage yet. >>>> Also, any specific reason why you are using dgmres and fgmres? >>>> >>>> PETSc has not been designed with multi-threading in mind. You can >>>> achieve “overlap” of the two solves by splitting the communicator. But then >>>> you need communications to let the two solutions talk to each other. >>>> >>>> Thanks >>>> Stefano >>>> >>>> >>>> On Aug 4, 2020, at 12:04 PM, nicola varini <nicola.var...@gmail.com> >>>> wrote: >>>> >>>> Dear all, thanks for your replies. The reason why I've asked if it is >>>> possible to overlap poisson and ampere is because they roughly >>>> take the same amount of time. Please find in attachment the profiling >>>> logs for only CPU and only GPU. >>>> Of course it is possible to split the MPI communicator and run each >>>> solver on different subcommunicator, however this would involve more >>>> communication. >>>> Did anyone ever tried to run 2 solvers with hyperthreading? >>>> Thanks >>>> >>>> >>>> Il giorno dom 2 ago 2020 alle ore 14:09 Mark Adams <mfad...@lbl.gov> >>>> ha scritto: >>>> >>>>> I suspect that the Poisson and Ampere's law solve are not coupled. You >>>>> might be able to duplicate the communicator and use two threads. You would >>>>> want to configure PETSc with threadsafty and threads and I think it >>>>> could/should work, but this mode is never used by anyone. >>>>> >>>>> That said, I would not recommend doing this unless you feel like >>>>> playing in computer science, as opposed to doing application science. The >>>>> best case scenario you get a speedup of 2x. That is a strict upper bound, >>>>> but you will never come close to it. Your hardware has some balance of CPU >>>>> to GPU processing rate. Your application has a balance of volume of work >>>>> for your two solves. They have to be the same to get close to 2x speedup >>>>> and that ratio(s) has to be 1:1. To be concrete, from what little I can >>>>> guess about your applications let's assume that the cost of each of these >>>>> two solves is about the same (eg, Laplacians on your domain and the best >>>>> case scenario). But, GPU machines are configured to have roughly 1-10% of >>>>> capacity in the GPUs, these days, that gives you an upper bound of about >>>>> 10% speedup. That is noise. Upshot, unless you configure your hardware to >>>>> match this problem, and the two solves have the same cost, you will not >>>>> see >>>>> close to 2x speedup. Your time is better spent elsewhere. >>>>> >>>>> Mark >>>>> >>>>> On Sat, Aug 1, 2020 at 3:24 PM Jed Brown <j...@jedbrown.org> wrote: >>>>> >>>>>> You can use MPI and split the communicator so n-1 ranks create a DMDA >>>>>> for one part of your system and the other rank drives the GPU in the >>>>>> other >>>>>> part. They can all be part of the same coupled system on the full >>>>>> communicator, but PETSc doesn't currently support some ranks having their >>>>>> Vec arrays on GPU and others on host, so you'd be paying host-device >>>>>> transfer costs on each iteration (and that might swamp any performance >>>>>> benefit you would have gotten). >>>>>> >>>>>> In any case, be sure to think about the execution time of each part. >>>>>> Load balancing with matching time-to-solution for each part can be really >>>>>> hard. >>>>>> >>>>>> >>>>>> Barry Smith <bsm...@petsc.dev> writes: >>>>>> >>>>>> > Nicola, >>>>>> > >>>>>> > This is really viable or practical at this time with PETSc. It >>>>>> is not impossible but requires careful coding with threads, another >>>>>> possibility is to use one half of the virtual GPUs for each solve, this >>>>>> is >>>>>> also not trivial. I would recommend first seeing what kind of performance >>>>>> you can get on the GPU for each type of solve and revist this idea in the >>>>>> future. >>>>>> > >>>>>> > Barry >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> >> On Jul 31, 2020, at 9:23 AM, nicola varini < >>>>>> nicola.var...@gmail.com> wrote: >>>>>> >> >>>>>> >> Hello, I would like to know if it is possible to overlap CPU and >>>>>> GPU with DMDA. >>>>>> >> I've a machine where each node has 1P100+1Haswell. >>>>>> >> I've to resolve Poisson and Ampere equation for each time step. >>>>>> >> I'm using 2D DMDA for each of them. Would be possible to compute >>>>>> poisson >>>>>> >> and ampere equation at the same time? One on CPU and the other on >>>>>> GPU? >>>>>> >> >>>>>> >> Thanks >>>>>> >>>>> <out_gpu><out_nogpu> >>>> >>>> >>>> >
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