Host: non-linear constraints

[simgrid.git] / examples / cpp / exec-cpu-nonlinear / s4u-exec-cpu-nonlinear.cpp

diff --git a/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.cpp b/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.cpp
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+/* Copyright (c) 2010-2021. 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. */
+
+/* This example shows how to simulate a non-linear resource sharing for
+ * CPUs.
+ */
+
+#include <simgrid/s4u.hpp>
+
+namespace sg4 = simgrid::s4u;
+
+XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_network_nonlinear, "Messages specific for this s4u example");
+
+/*************************************************************************************************/
+static void runner()
+{
+  double computation_amount = sg4::this_actor::get_host()->get_speed();
+  int n_task                = 10;
+  std::vector<sg4::ExecPtr> tasks;
+
+  XBT_INFO(
+      "Execute %d tasks of %g flops, should take %d second in a CPU without degradation. It will take the double here.",
+      n_task, computation_amount, n_task);
+  for (int i = 0; i < n_task; i++) {
+    tasks.emplace_back(sg4::this_actor::exec_async(computation_amount));
+  }
+  XBT_INFO("Waiting for all tasks to be done!");
+  for (auto& task : tasks)
+    task->wait();
+
+  XBT_INFO("Finished executing. Goodbye now!");
+}
+/*************************************************************************************************/
+/** @brief Non-linear resource sharing for CPU */
+static double cpu_nonlinear(const sg4::Host* host, double capacity, int n)
+{
+  /* emulates a degradation in link according to the number of flows
+   * totally unrealistic but for learning purposes */
+  capacity = n > 1 ? capacity / 2 : capacity;
+  XBT_INFO("Host %s, %d concurrent tasks, new capacity %lf", host->get_cname(), n, capacity);
+  return capacity;
+}
+
+/** @brief Create a simple 1-host platform */
+static void load_platform()
+{
+  auto* zone        = sg4::create_empty_zone("Zone1");
+  auto* runner_host = zone->create_host("runner", 1e6);
+  runner_host->set_sharing_policy(sg4::Host::SharingPolicy::NONLINEAR,
+                                  std::bind(&cpu_nonlinear, runner_host, std::placeholders::_1, std::placeholders::_2));
+  runner_host->seal();
+  zone->seal();
+
+  /* create actor runner */
+  sg4::Actor::create("runner", runner_host, runner);
+}
+
+/*************************************************************************************************/
+int main(int argc, char* argv[])
+{
+  sg4::Engine e(&argc, argv);
+
+  /* create platform */
+  load_platform();
+
+  /* runs the simulation */
+  e.run();
+
+  return 0;
+}