Mark, The problem is indeed non-symmetric. We went back and forth in March about this problem. I think we ended up concluding that the coarse size couldn't get too small or the null-space presented problems. When I did get it to work, I tried to scale it up, and on my local university cluster, it seemed to just hang when the core counts got above something like 16 cores. I don't really trust that machine though. It's new and has been plagued by hardware incompatability issues since day 1. I could re-examine this on Kraken. Also, what option are you talking about with ML. I thought I had tried all the -pc_ml_CoarsenScheme options, but I could be wrong.
John On Mon, Jul 9, 2012 at 11:30 AM, Mark F. Adams <mark.adams at columbia.edu>wrote: > What problems are you having again with GAMG? Are you problems > unsymmetric? > > ML has several coarsening strategies available and I think the default > does aggregation locally and does not aggregate across processor > subdomains. If you have poorly shaped domains then you want to use a > global coarsening method (these are not expensive). > > Mark > > On Jul 9, 2012, at 12:17 PM, John Mousel wrote: > > Mark, > > I still haven't had much luck getting GAMG to work consistently for my > Poisson problem. ML seems to work nicely on low core counts, but I have a > problem where I can get long thin portions of grid on some processors > instead of nice block like chunks at high core counts, which leads to a > pretty tough time for ML. > > John > > On Mon, Jul 9, 2012 at 10:58 AM, John Mousel <john.mousel at gmail.com>wrote: > >> Getting rid of the Hypre option seemed to be the trick. >> >> On Mon, Jul 9, 2012 at 10:40 AM, Mark F. Adams <mark.adams at >> columbia.edu>wrote: >> >>> Google PTL_NO_SPACE and you will find some NERSC presentations on how to >>> go about fixing this. (I have run into these problems years ago but forget >>> the issues) >>> >>> Also, I would try running with a Jacobi solver to see if that fixes the >>> problem. If so then you might try >>> >>> -pc_type gamg >>> -pc_gamg_agg_nsmooths 1 >>> -pc_gamg_type agg >>> >>> This is a built in AMG solver so perhaps it plays nicer with resources >>> ... >>> >>> Mark >>> >>> On Jul 9, 2012, at 10:57 AM, John Mousel wrote: >>> >>> > I'm running on Kraken and am currently working with 4320 cores. I get >>> the following error in KSPSolve. >>> > >>> > [2711]: >>> (/ptmp/ulib/mpt/nightly/5.3/120211/mpich2/src/mpid/cray/src/adi/ptldev.c:2046) >>> PtlMEInsert failed with error : PTL_NO_SPACE >>> > MHV_exe: >>> /ptmp/ulib/mpt/nightly/5.3/120211/mpich2/src/mpid/cray/src/adi/ptldev.c:2046: >>> MPIDI_CRAY_ptldev_desc_pkt: Assertion `0' failed. >>> > forrtl: error (76): Abort trap signal >>> > Image PC Routine Line >>> Source >>> > MHV_exe 00000000014758CB Unknown Unknown >>> Unknown >>> > MHV_exe 000000000182ED43 Unknown Unknown >>> Unknown >>> > MHV_exe 0000000001829460 Unknown Unknown >>> Unknown >>> > MHV_exe 00000000017EDE3E Unknown Unknown >>> Unknown >>> > MHV_exe 00000000017B3FE6 Unknown Unknown >>> Unknown >>> > MHV_exe 00000000017B3738 Unknown Unknown >>> Unknown >>> > MHV_exe 00000000017B2B12 Unknown Unknown >>> Unknown >>> > MHV_exe 00000000017B428F Unknown Unknown >>> Unknown >>> > MHV_exe 000000000177FCE1 Unknown Unknown >>> Unknown >>> > MHV_exe 0000000001590A43 Unknown Unknown >>> Unknown >>> > MHV_exe 00000000014F909B Unknown Unknown >>> Unknown >>> > MHV_exe 00000000014FF53B Unknown Unknown >>> Unknown >>> > MHV_exe 00000000014A4E25 Unknown Unknown >>> Unknown >>> > MHV_exe 0000000001487D57 Unknown Unknown >>> Unknown >>> > MHV_exe 000000000147F726 Unknown Unknown >>> Unknown >>> > MHV_exe 000000000137A8D3 Unknown Unknown >>> Unknown >>> > MHV_exe 0000000000E97BF2 Unknown Unknown >>> Unknown >>> > MHV_exe 000000000098EAF1 Unknown Unknown >>> Unknown >>> > MHV_exe 0000000000989C20 Unknown Unknown >>> Unknown >>> > MHV_exe 000000000097A9C2 Unknown Unknown >>> Unknown >>> > MHV_exe 000000000082FF2D axbsolve_ 539 >>> PetscObjectsOperations.F90 >>> > >>> > This is somewhere in KSPSolve. Is there an MPICH environment variable >>> that needs tweaking? I couldn't really find much on this particular error. >>> > The solver is BiCGStab with Hypre as a preconditioner. >>> > >>> > -ksp_type bcgsl -pc_type hypre -pc_hypre_type boomeramg -ksp_monitor >>> > >>> > Thanks, >>> > >>> > John >>> >>> >> > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120709/37f6936f/attachment-0001.html>
