On Fri, Dec 2, 2011 at 6:20 PM, Dave Nystrom <Dave.Nystrom at tachyonlogic.com>wrote:
> I never received any reply to this question but would very much appreciate > one. Not sure if it fell through the cracks. > you can do whatever you want in PCSHELL. I would look at sacusp, since this does about what you want. Matt > Thanks, > > Dave > > Dave Nystrom writes: > > I have a 2d resistive mhd code interfaced to petsc. The code has seven > > different linear solves per timestep and these linear solves consume > around > > 95 percent of the run time for a reasonably small grid of 100x301. The > run > > time is dominated by the solution of one of the linear solves that is > > particularly difficult to solve. This particular linear solve actually > takes > > about 80 percent of the total run time. All of these linear systems are > > symmetric. I am actually able to run a simulation where I am using > jacobi > > preconditioning with conjugate gradient on a gpu and get a solution and > this > > is the fastest solution which I currently get but the iteration count > ranges > > from a minimum of 771 to a max of 47300 for the difficult linear system. > > > > We also have a native cg solver in the code which uses a full cholesky > band > > solve of the inner set of bands and that solver has a much better > iteration > > count although it takes a bit over 2x the run time of petsc w/ jacobi > and > > cusp. So, I have been interested in making a custom petsc > preconditioner > > that does this cholesky solve using the PCSHELL capability of petsc. > And I'm > > interested in trying to do this cholesky solve on the GPU using a CULA > SPARSE > > band solver. However, I'm wondering if the petsc PCSHELL capability > only > > runs on the cpu and if I would need a GPU analog such as a PCGPUSHELL > > capability in petsc. I'm wondering if this is the case and if so, > whether > > there is a possibility that a PCGPUSHELL capability might be added to > petsc > > in the near term. > > > > Thanks, > > > > Dave > > > > -- > > Dave Nystrom > > > > phone: 505-661-9943 (home office) > > 505-662-6893 (home) > > skype: dave.nystrom76 > > email: dnystrom1 at comcast.net > > smail: 219 Loma del Escolar > > Los Alamos, NM 87544 > -- 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20111202/a43d84d4/attachment.html>