Thanks Matt. Attached detailed info on ksp of a much smaller test. This is a multiphysics problem.
Hom Nath On Fri, Jan 22, 2016 at 12:01 PM, Matthew Knepley <[email protected]> wrote: > On Fri, Jan 22, 2016 at 10:52 AM, Hom Nath Gharti <[email protected]> > wrote: >> >> Dear all, >> >> I take this opportunity to ask for your important suggestion. >> >> I am solving an elastic-acoustic-gravity equation on the planet. I >> have displacement vector (ux,uy,uz) in solid region, displacement >> potential (\xi) and pressure (p) in fluid region, and gravitational >> potential (\phi) in all of space. All these variables are coupled. >> >> Currently, I am using MATMPIAIJ and form a single global matrix. Does >> using a MATMPIBIJ or MATNEST improve the convergence/efficiency in >> this case? For your information, total degrees of freedoms are about a >> billion. > > > 1) For any solver question, we need to see the output of -ksp_view, and we > would also like > > -ksp_monitor_true_residual -ksp_converged_reason > > 2) MATNEST does not affect convergence, and MATMPIBAIJ only in the blocksize > which you > could set without that format > > 3) However, you might see benefit from using something like PCFIELDSPLIT if > you have multiphysics here > > Matt > >> >> Any suggestion would be greatly appreciated. >> >> Thanks, >> Hom Nath >> >> On Fri, Jan 22, 2016 at 10:32 AM, Matthew Knepley <[email protected]> >> wrote: >> > On Fri, Jan 22, 2016 at 9:27 AM, Mark Adams <[email protected]> wrote: >> >>> >> >>> >> >>> >> >>> I said the Hypre setup cost is not scalable, >> >> >> >> >> >> I'd be a little careful here. Scaling for the matrix triple product is >> >> hard and hypre does put effort into scaling. I don't have any data >> >> however. >> >> Do you? >> > >> > >> > I used it for PyLith and saw this. I did not think any AMG had scalable >> > setup time. >> > >> > Matt >> > >> >>> >> >>> but it can be amortized over the iterations. You can quantify this >> >>> just by looking at the PCSetUp time as your increase the number of >> >>> processes. I don't think they have a good >> >>> model for the memory usage, and if they do, I do not know what it is. >> >>> However, generally Hypre takes more >> >>> memory than the agglomeration MG like ML or GAMG. >> >>> >> >> >> >> agglomerations methods tend to have lower "grid complexity", that is >> >> smaller coarse grids, than classic AMG like in hypre. THis is more of a >> >> constant complexity and not a scaling issue though. You can address >> >> this >> >> with parameters to some extent. But for elasticity, you want to at >> >> least >> >> try, if not start with, GAMG or ML. >> >> >> >>> >> >>> Thanks, >> >>> >> >>> Matt >> >>> >> >>>> >> >>>> >> >>>> Giang >> >>>> >> >>>> On Mon, Jan 18, 2016 at 5:25 PM, Jed Brown <[email protected]> wrote: >> >>>>> >> >>>>> Hoang Giang Bui <[email protected]> writes: >> >>>>> >> >>>>> > Why P2/P2 is not for co-located discretization? >> >>>>> >> >>>>> Matt typed "P2/P2" when me meant "P2/P1". >> >>>> >> >>>> >> >>> >> >>> >> >>> >> >>> -- >> >>> 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 > > > > > -- > 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
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