Let me get more debugging information first. code were implemented in a bunch of different files. simply copy-and-paste will make it very messy.
On Sun, Sep 17, 2017 at 1:38 AM, Barry Smith <[email protected]> wrote: > > Send a code fragment that reproduces the problem; you must be calling on > the wrong KSP or at the wrong place in the code > > > On Sep 17, 2017, at 12:33 AM, Hao Zhang <[email protected]> wrote: > > > > Call KSPView(). this is I have from the output > > > > for my COARSE grid: > > > > imin = 4 imax = 41 > > jmin = 4 jmax = 8 > > kmin = 4 kmax = 20 > > KSP Object: 24 MPI processes > > type not yet set > > maximum iterations=20, initial guess is zero > > tolerances: relative=1e-05, absolute=1e-50, divergence=10000 > > left preconditioning > > using DEFAULT norm type for convergence test > > PC Object: 24 MPI processes > > type not yet set > > PC has not been set up so information may be incomplete > > KSP Object: 24 MPI processes > > type not yet set > > maximum iterations=20, initial guess is zero > > tolerances: relative=1e-14, absolute=1e-50, divergence=10000 > > left preconditioning > > using DEFAULT norm type for convergence test > > PC Object: 24 MPI processes > > type not yet set > > PC has not been set up so information may be incomplete > > > > Using Neumann Solver > > 0 KSP Residual norm 4.933753594518e+00 > > 2 KSP Residual norm 1.028883218492e-03 > > 4 KSP Residual norm 2.980337307701e-06 > > 6 KSP Residual norm 2.976110274418e-06 > > 8 KSP Residual norm 2.976110265786e-06 > > 10 KSP Residual norm 2.976110265696e-06 > > 12 KSP Residual norm 2.976158755617e-06 > > 14 KSP Residual norm 2.976038363683e-06 > > 16 KSP Residual norm 2.976102606899e-06 > > 18 KSP Residual norm 2.976429345213e-06 > > Linear solve did not converge due to DIVERGED_ITS iterations 18 > > > > The solution diverges! The residual is 2.976429e-06. Solve again using > GMRES! > > 0 KSP Residual norm 4.932103470452e+00 > > 1 KSP Residual norm 4.586081825060e-01 > > 2 KSP Residual norm 4.702606826126e-02 > > 3 KSP Residual norm 5.717152414461e-03 > > 4 KSP Residual norm 5.122354290806e-04 > > 5 KSP Residual norm 4.682702445806e-05 > > 6 KSP Residual norm 4.368929895884e-06 > > 7 KSP Residual norm 4.908451624092e-07 > > 8 KSP Residual norm 4.758895647974e-08 > > 9 KSP Residual norm 3.831683374269e-09 > > 10 KSP Residual norm 2.844848230467e-10 > > 11 KSP Residual norm 2.252748969152e-11 > > 12 KSP Residual norm 1.432700892770e-12 > > 13 KSP Residual norm 9.569163228927e-14 > > 14 KSP Residual norm 1.129667714748e-14 > > Linear solve converged due to CONVERGED_RTOL iterations 14 > > > > In poisson_func(): num_iter = 14, rel_residual = 1.129668e-14 > > > > for my REFINE grid: > > > > imin = 4 imax = 28 > > jmin = 4 jmax = 10 > > kmin = 4 kmax = 28 > > KSP Object: 96 MPI processes > > type not yet set > > maximum iterations=20, initial guess is zero > > tolerances: relative=1e-05, absolute=1e-50, divergence=10000 > > left preconditioning > > using DEFAULT norm type for convergence test > > PC Object: 96 MPI processes > > type not yet set > > PC has not been set up so information may be incomplete > > KSP Object: 96 MPI processes > > type not yet set > > maximum iterations=20, initial guess is zero > > tolerances: relative=1e-14, absolute=1e-50, divergence=10000 > > left preconditioning > > using DEFAULT norm type for convergence test > > PC Object: 96 MPI processes > > type not yet set > > PC has not been set up so information may be incomplete > > > > On Sun, Sep 17, 2017 at 1:22 AM, Hao Zhang <[email protected]> wrote: > > Thanks! > > > > On Sun, Sep 17, 2017 at 1:20 AM, Barry Smith <[email protected]> wrote: > > > > > On Sep 17, 2017, at 12:17 AM, Hao Zhang <[email protected]> wrote: > > > > > > OK. I will check the output Calling KSPView() > > > > > > I am experimenting with -start_in_debugger. it's for serial not for > parallel, right? > > > > It can be for parallel, opens an xterm with the debugger for each MPI > process. You need to type cont in all the windows > > > > > > > > > > On Sun, Sep 17, 2017 at 1:12 AM, Barry Smith <[email protected]> > wrote: > > > > > > Should work in the code also. Call KSPSetTolerances() and then call > KSPView() to see what it is set to > > > > > > > On Sep 17, 2017, at 12:11 AM, Hao Zhang <[email protected]> wrote: > > > > > > > > Yes. but only works via command line option.before was set up in the > code. > > > > > > > > On Sun, Sep 17, 2017 at 12:44 AM, Barry Smith <[email protected]> > wrote: > > > > > > > > > On Sep 16, 2017, at 11:33 PM, Hao Zhang <[email protected]> > wrote: > > > > > > > > > > thanks. > > > > > > > > > > Yes. KSPSetTolerances is used. > > > > > > > > > > tolerance is set to be 1.e-14 > > > > > > > > There is the rtol and atol are you sure you set the atol to 1e-14? > > > > > > > > > > > > > > I was thinking if there is a debug option I could use from PETSc > to get some insight? GDB was used. > > > > > > > > You can use the command line option -start_in_debugger > > > > > > > > > > > > > > > > > > On Sun, Sep 17, 2017 at 12:25 AM, Barry Smith <[email protected]> > wrote: > > > > > > > > > > > On Sep 16, 2017, at 10:39 PM, Hao Zhang <[email protected]> > wrote: > > > > > > > > > > > > hi, > > > > > > > > > > > > I am using KSPBCGSL method and HYPRE boomeramg precondtioner > passed into KSPsolve for poisson equation as part of incompressible NS. > > > > > > > > > > > > I have two questions > > > > > > Q1 is number of iterations for the same solver. max_iter = 20 > for the same poisson function > > > > > > > > > > > > KSPGetIterationNumber() is used to set up max_iter = 20 > > > > > > > > > > What do you mean, KSPGetIterationNumber() tells you the current > number of iterations. You cannot use it to set the maximum number of > iterations. Use KSPSetTolerances() or -ksp_max_it <its> to set the number > > > > > > > > > > > > > > > > > > 0 KSP Residual norm 4.512245447770e-04 > > > > > > 2 KSP Residual norm 6.396709069731e-07 > > > > > > 4 KSP Residual norm 1.757784220489e-10 > > > > > > 6 KSP Residual norm 1.501464709144e-14 > > > > > > 8 KSP Residual norm 1.376381429122e-18 > > > > > > 10 KSP Residual norm 1.072650548945e-19 > > > > > > In poisson_func(): num_iter = 10, rel_residual = 1.072651e-19 > > > > > > > > > > > > and the very same function at the next time step gives: remind > you guys max_iter = 20. I assume the number of iterations should stop at > num_iter = 2. > > > > > > > > > > Why would it stop at num_iter 2. The number of iterations > allowed is the same for each solve, it does not accumulate over all solves. > > > > > > > > > > > but the solver seems to keep iterating util hitting the > max_iter. > > > > > > 0 KSP Residual norm 5.107005838093e-16 > > > > > > 2 KSP Residual norm 3.353634821198e-20 > > > > > > 4 KSP Residual norm 1.835096039266e-23 > > > > > > 6 KSP Residual norm 1.645496102409e-23 > > > > > > 8 KSP Residual norm 1.645496099837e-23 > > > > > > 10 KSP Residual norm 1.645496099836e-23 > > > > > > 12 KSP Residual norm 1.645496099530e-23 > > > > > > 14 KSP Residual norm 1.645496034473e-23 > > > > > > 16 KSP Residual norm 1.645461130961e-23 > > > > > > 18 KSP Residual norm 1.645460451075e-23 > > > > > > In poisson_func(): num_iter = 18, rel_residual = 1.645460e-23 > > > > > > > > > > But the way it is almost never realistic to try to get residual > norms to be this small. You might consider using something like -ksp_atol > 1.e-16 or something > > > > > > > > > > > > > > > > > Q2 is: it seems HYPRE with KSPsolve works with coarse mesh but > when I double the mesh size. the solve halted indefinitely. ksp_monitor > didn't produce any results. > > > > > > is there a way to understand what's happening? > > > > > > > > > > You could run in the debugger and use control c to interrupt > the code when it is "hanging" and type bt to see the stack trace for the > hanging. > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > Hao Zhang > > > > > > Dept. of Applid Mathematics and Statistics, > > > > > > Stony Brook University, > > > > > > Stony Brook, New York, 11790 > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Hao Zhang > > > > > Dept. of Applid Mathematics and Statistics, > > > > > Stony Brook University, > > > > > Stony Brook, New York, 11790 > > > > > > > > > > > > > > > > > > > > -- > > > > Hao Zhang > > > > Dept. of Applid Mathematics and Statistics, > > > > Stony Brook University, > > > > Stony Brook, New York, 11790 > > > > > > > > > > > > > > > -- > > > Hao Zhang > > > Dept. of Applid Mathematics and Statistics, > > > Stony Brook University, > > > Stony Brook, New York, 11790 > > > > > > > > > > -- > > Hao Zhang > > Dept. of Applid Mathematics and Statistics, > > Stony Brook University, > > Stony Brook, New York, 11790 > > > > > > > > -- > > Hao Zhang > > Dept. of Applid Mathematics and Statistics, > > Stony Brook University, > > Stony Brook, New York, 11790 > > -- Hao Zhang Dept. of Applid Mathematics and Statistics, Stony Brook University, Stony Brook, New York, 11790
