From: Martin Kronbichler <martin.kronbichler@rub.de>
Date: Fri, 15 Mar 2024 08:46:49 +0000 (+0100)
Subject: Fix unnecessary allreduce
X-Git-Tag: v9.6.0-rc1~473^2~2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=16f9a006ebcc4b9eb6e3ac6b34514d31d0c6c743;p=dealii.git

Fix unnecessary allreduce
---

diff --git a/include/deal.II/lac/solver_gmres.h b/include/deal.II/lac/solver_gmres.h
index 6df1e9a0ec..baa9a04b14 100644
--- a/include/deal.II/lac/solver_gmres.h
+++ b/include/deal.II/lac/solver_gmres.h
@@ -1283,8 +1283,12 @@ namespace internal
             }
         }
 
-      return std::sqrt(
-        Utilities::MPI::sum(norm_vv_temp, block(vv, 0).get_mpi_communicator()));
+      if (delayed_reorthogonalization)
+        return std::numeric_limits<double>::signaling_NaN();
+      else
+        return std::sqrt(
+          Utilities::MPI::sum(norm_vv_temp,
+                              block(vv, 0).get_mpi_communicator()));
     }