Use host->set_concurrency_limit(1) in an example where it makes sense

[simgrid.git] / examples / cpp / dag-scheduling / s4u-dag-scheduling.cpp

diff --git a/examples/cpp/dag-scheduling/s4u-dag-scheduling.cpp b/examples/cpp/dag-scheduling/s4u-dag-scheduling.cpp
index da4e24b..97938f2 100644 (file)
--- a/examples/cpp/dag-scheduling/s4u-dag-scheduling.cpp
+++ b/examples/cpp/dag-scheduling/s4u-dag-scheduling.cpp
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009-2022. The SimGrid Team. All rights reserved.          */
+/* Copyright (c) 2009-2023. The SimGrid Team. All rights reserved.          */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
@@ -165,10 +165,17 @@ int main(int argc, char** argv)
   });
 
   e.load_platform(argv[1]);
+  const auto hosts = e.get_all_hosts();
+
+  /* Mark all hosts as sequential, as it ought to be in such a scheduling example.
+   *
+   * It means that the hosts can only compute one thing at a given time. If an execution already takes place on a given
+   * host, any subsequently started execution will be queued until after the first execution terminates */
+  for (auto const& host : hosts)
+    host->set_concurrency_limit(1);
 
   /*  Allocating the host attribute */
   unsigned long total_nhosts = e.get_host_count();
-  const auto hosts          = e.get_all_hosts();
   std::vector<HostAttribute> host_attributes(total_nhosts);
   for (unsigned long i = 0; i < total_nhosts; i++)
     hosts[i]->set_data(&host_attributes[i]);
@@ -225,8 +232,8 @@ int main(int argc, char** argv)
      * new dependency
      */
 
-    auto last_scheduled_task = sg_host_get_last_scheduled_task(selected_host);
-    if (last_scheduled_task && (last_scheduled_task->get_state() != sg4::Activity::State::FINISHED) &&
+    if (auto last_scheduled_task = sg_host_get_last_scheduled_task(selected_host);
+        last_scheduled_task && (last_scheduled_task->get_state() != sg4::Activity::State::FINISHED) &&
         (last_scheduled_task->get_state() != sg4::Activity::State::FAILED) &&
         not dependency_exists(sg_host_get_last_scheduled_task(selected_host), selected_task))
       last_scheduled_task->add_successor(selected_task);