From: Daniel Arndt <daniel.arndt@iwr.uni-heidelberg.de>
Date: Fri, 18 May 2018 17:08:52 +0000 (+0200)
Subject: Clarify which MPI_Comm is referred to in a comment
X-Git-Tag: v9.1.0-rc1~1127^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F6616%2Fhead;p=dealii.git

Clarify which MPI_Comm is referred to in a comment
---

diff --git a/source/base/process_grid.cc b/source/base/process_grid.cc
index f75596fe17..dfd36e5955 100644
--- a/source/base/process_grid.cc
+++ b/source/base/process_grid.cc
@@ -168,8 +168,10 @@ namespace Utilities
                             &inactive_with_root_group);
       AssertThrowMPI(ierr);
 
-      // Create the communicator based on the group
-      // Note that on most cores the communicator will be MPI_COMM_NULL.
+      // Create the communicator based on inactive_with_root_group.
+      // Note that on all the active MPI processes (except for the one with
+      // rank 0) the resulting MPI_Comm mpi_communicator_inactive_with_root
+      // will be MPI_COMM_NULL.
       ierr = Utilities::MPI::create_group(mpi_communicator, inactive_with_root_group,
                                           55, &mpi_communicator_inactive_with_root);
       AssertThrowMPI(ierr);