From: Peter Munch Date: Sun, 14 Mar 2021 16:21:56 +0000 (+0100) Subject: Extend text regarding allow_artificial_cells X-Git-Tag: v9.3.0-rc1~305^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F11910%2Fhead;p=dealii.git Extend text regarding allow_artificial_cells --- diff --git a/include/deal.II/distributed/shared_tria.h b/include/deal.II/distributed/shared_tria.h index 0d4efafe5e..798a7b9be4 100644 --- a/include/deal.II/distributed/shared_tria.h +++ b/include/deal.II/distributed/shared_tria.h @@ -228,11 +228,25 @@ namespace parallel /** * Constructor. * - * If @p allow_aritifical_cells is true, this class will behave similar - * to parallel::distributed::Triangulation in that there will be locally - * owned, ghost and artificial cells. + * The flag @p allow_artificial_cells can be used to enable artifical + * cells. If enabled, this class will behave similarly + * to parallel::distributed::Triangulation and + * parallel::fullydistributed::Triangulation in the sense that there will + * be locally owned cells, a single layer of ghost cells, and + * artificial cells. However, one should not forget that in contrast to + * those parallel triangulations all cells are duplicated on all + * processes, leading in most cases to significantly more artificial + * cells. * - * Otherwise all non-locally owned cells are considered ghost. + * If artificial cells are disabled, all non-locally owned cells are + * considered ghost cells. This might lead to very expensive ghost-value + * update steps. While in the case of artificial cells, ghost-value + * updates lead to communication only with the direct process neighbors in + * a point-to-point fashion, these degenerate to an operation in which + * every process communicates with every other process (an "all-to-all" + * communication) if no artifical cells are available. If such ghost-value + * updates are the bottleneck in your code, you may want to consider + * enabling artificial cells. */ Triangulation( const MPI_Comm &mpi_communicator,