Dear Firedrake -- Following up with more clarity on my part, I see that the warning comes from get_transfer_operators() in dmhooks. Furthermore, I see that I do not get the warning when using -pc_type mg in simple things (like Poisson). Apparently it arises because I am using options like -pc_type fieldsplit -fieldsplit_0_pc_type mg and etc. The demo geometric_multigrid.py and my own code solve the Stokes equations. So I am guessing that I should not be putting anything into my own (application) appctx, but rather this is about a Firedrake object's existing appctx? I am trying to interpret the top of the dmhooks docstring """ Firedrake uses PETSc for its linear and nonlinear solvers. The interaction is carried out through DM objects. These carry around any user-defined application context and can be used to inform the solvers how to create field decompositions (for fieldsplit preconditioning) as well as creating sub-DMs (which only contain some fields), along with multilevel information (for geometric multigrid) """ I am going fishing for info on whether *I* should be fixing something or ya'll should be, to make the warning go away and/or to setup and store the appropriate DM info so that the warning is not triggered. Thanks, and noting that Firedrake really works for me, Ed On Sat, Apr 18, 2020 at 6:15 PM Ed Bueler <elbueler@alaska.edu> wrote:
Dear Firedrake --
When I run the demo code https://www.firedrakeproject.org/demos/geometric_multigrid.py.html I get output with the warning
firedrake:WARNING Creating new TransferManager to transfer data to coarse grids firedrake:WARNING This might be slow (you probably want to save it on an appctx)
The same warning appears for my own codes, which often use -pc_type mg. This is new behavior for me, i.e. as of a firedrake update about 2 months ago. How should I update this demo to avoid the warning message?
Is there an example where it is added to an appctx? I'm curious about the cause of the warning, because I would not want mesh-specific info in a PETSc appctx, generally, I think ...
Thanks!
Ed
-- Ed Bueler Dept of Mathematics and Statistics University of Alaska Fairbanks Fairbanks, AK 99775-6660 306C Chapman
-- Ed Bueler Dept of Mathematics and Statistics University of Alaska Fairbanks Fairbanks, AK 99775-6660 306C Chapman