If mmg does not support parallel communicators, we should handle it internally in the code, always use commself, and raise an error if there are two or more processes in the comm that have cEnd - cStart > 0
Il giorno mer 23 apr 2025 alle ore 20:05 neil liu <liufi...@gmail.com> ha scritto: > Thanks a lot. Pierre. > Do you have any suggestions to build a real serial DM from this gatherDM? > I tried several ways, which don't work. > DMClone? > > Thanks, > > On Wed, Apr 23, 2025 at 11:39 AM Pierre Jolivet <pie...@joliv.et> wrote: > >> >> >> On 23 Apr 2025, at 5:31 PM, neil liu <liufi...@gmail.com> wrote: >> >> Thanks a lot, Stefano. >> I tried DMPlexGetGatherDM and DMPlexDistributeField. It can give what we >> expected. >> The final gatherDM is listed as follows, rank 0 has all information >> (which is right) while rank 1 has nothing. >> Then I tried to feed this gatherDM into adaptMMG on rank 0 only (it >> seems MMG works better than ParMMG, that is why I want MMG to be tried >> first). But it was stuck at collective petsc functions >> in DMAdaptMetric_Mmg_Plex(). By the way, the present work can work well >> with 1 rank. >> >> Do you have any suggestions ? Build a real serial DM? >> >> >> Yes, you need to change the underlying MPI_Comm as well, but I’m not sure >> if there is any user-facing API for doing this with a one-liner. >> >> Thanks, >> Pierre >> >> Thanks a lot. >> Xiaodong >> >> DM Object: Parallel Mesh 2 MPI processes >> type: plex >> Parallel Mesh in 3 dimensions: >> Number of 0-cells per rank: 56 0 >> Number of 1-cells per rank: 289 0 >> Number of 2-cells per rank: 452 0 >> Number of 3-cells per rank: 216 0 >> Labels: >> depth: 4 strata with value/size (0 (56), 1 (289), 2 (452), 3 (216)) >> celltype: 4 strata with value/size (0 (56), 1 (289), 3 (452), 6 (216)) >> Cell Sets: 2 strata with value/size (29 (152), 30 (64)) >> Face Sets: 3 strata with value/size (27 (8), 28 (40), 101 (20)) >> Edge Sets: 1 strata with value/size (10 (10)) >> Vertex Sets: 5 strata with value/size (27 (2), 28 (6), 29 (2), 101 (4), >> 106 (4)) >> Field Field_0: >> adjacency FEM >> >> >> >> On Fri, Apr 18, 2025 at 10:09 AM Stefano Zampini < >> stefano.zamp...@gmail.com> wrote: >> >>> If you have a vector distributed on the original mesh, then you can use >>> the SF returned by DMPlexGetGatherDM and use that in a call to >>> DMPlexDistributeField >>> >>> Il giorno ven 18 apr 2025 alle ore 17:02 neil liu <liufi...@gmail.com> >>> ha scritto: >>> >>>> Dear PETSc developers and users, >>>> >>>> I am currently exploring the integration of MMG3D with PETSc. Since >>>> MMG3D supports only serial execution, I am planning to combine parallel and >>>> serial computing in my workflow. Specifically, after solving the linear >>>> systems in parallel using PETSc: >>>> >>>> 1. >>>> >>>> I intend to use DMPlexGetGatherDM to collect the entire mesh on the >>>> root process for input to MMG3D. >>>> 2. >>>> >>>> Additionally, I plan to gather the error field onto the root >>>> process using VecScatter. >>>> >>>> However, I am concerned that the nth value in the gathered error vector >>>> (step 2) may not correspond to the nth element in the gathered mesh (step >>>> 1). Is this a valid concern? >>>> >>>> Do you have any suggestions or recommended practices for ensuring >>>> correct correspondence between the solution fields and the mesh when >>>> switching from parallel to serial mode? >>>> >>>> Thanks, >>>> >>>> Xiaodong >>>> >>> >>> >>> -- >>> Stefano >>> >> >> -- Stefano
