From f1711862efa6acb2ce97cff16efd8ac4e86c9735 Mon Sep 17 00:00:00 2001
From: Timo Heister <timo.heister@gmail.com>
Date: Thu, 18 Apr 2013 18:45:56 +0000
Subject: [PATCH] fix TimerOutput wall_time in parallel not being synchronized
 as one expects.

git-svn-id: https://svn.dealii.org/trunk@29333 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/doc/news/changes.h           | 7 +++++++
 deal.II/include/deal.II/base/timer.h | 2 ++
 deal.II/source/base/timer.cc         | 8 ++++++++
 3 files changed, 17 insertions(+)

diff --git a/deal.II/doc/news/changes.h b/deal.II/doc/news/changes.h
index 7884f7c326..99f39f441c 100644
--- a/deal.II/doc/news/changes.h
+++ b/deal.II/doc/news/changes.h
@@ -64,6 +64,13 @@ this function.
 
 
 <ol>
+  <li> Fixed: TimerOutput constructed with an MPI_COMM in wall_time
+  mode now constructs synchronized Timer objects. This gives reliable
+  parallel benchmark timings.
+  <br>
+  (Timo Heister, 2013/04/18)
+  </li>
+
   <li> New: The step-49 tutorial program now also has a discussion on
   what to do once you have a coarse mesh and want to refine it.
   <br>
diff --git a/deal.II/include/deal.II/base/timer.h b/deal.II/include/deal.II/base/timer.h
index 9450b20a6d..d9f36d9b7e 100644
--- a/deal.II/include/deal.II/base/timer.h
+++ b/deal.II/include/deal.II/base/timer.h
@@ -409,6 +409,8 @@ public:
    */
   void enter_section (const std::string &section_name);
 
+  //TODO: make some of these functions DEPRECATED (I would keep enter/exit_section)
+
   /**
    * Leave a section. If no name is given,
    * the last section that was entered is
diff --git a/deal.II/source/base/timer.cc b/deal.II/source/base/timer.cc
index a1be012b22..2c0b9cf2f9 100644
--- a/deal.II/source/base/timer.cc
+++ b/deal.II/source/base/timer.cc
@@ -350,6 +350,14 @@ TimerOutput::enter_subsection (const std::string &section_name)
 
   if (sections.find (section_name) == sections.end())
     {
+#ifdef DEAL_II_WITH_MPI
+      if (mpi_communicator != MPI_COMM_SELF)
+        {
+          sections[section_name].timer = Timer(mpi_communicator, true);
+        }
+#endif
+
+
       sections[section_name].total_cpu_time = 0;
       sections[section_name].total_wall_time = 0;
       sections[section_name].n_calls = 0;
-- 
2.39.5