--- /dev/null
+/* Copyright (c) 2010, 2012-2016. 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. */
+
+#include "simgrid/plugins/load.h"
+#include "simgrid/simix.hpp"
+#include "src/plugins/vm/VirtualMachineImpl.hpp"
+#include "src/surf/cpu_interface.hpp"
+
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/split.hpp>
+#include <simgrid/s4u/engine.hpp>
+#include <string>
+#include <utility>
+#include <vector>
+
+/** @addtogroup SURF_plugin_load
+
+This plugin makes it very simple for users to obtain the current load for each host.
+
+*/
+
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_plugin_load, surf, "Logging specific to the SURF HostLoad plugin");
+
+namespace simgrid {
+namespace plugin {
+
+class HostLoad {
+public:
+ static simgrid::xbt::Extension<simgrid::s4u::Host, HostLoad> EXTENSION_ID;
+
+ explicit HostLoad(simgrid::s4u::Host* ptr);
+ ~HostLoad();
+
+ double getCurrentLoad();
+ double getComputedFlops();
+ void update();
+ void reset();
+
+private:
+ simgrid::s4u::Host* host = nullptr;
+ double last_updated = 0;
+ double current_flops = 0;
+ double computed_flops = 0;
+};
+
+simgrid::xbt::Extension<simgrid::s4u::Host, HostLoad> HostLoad::EXTENSION_ID;
+
+HostLoad::HostLoad(simgrid::s4u::Host* ptr)
+ : host(ptr), last_updated(surf_get_clock()), current_flops(lmm_constraint_get_usage(host->pimpl_cpu->constraint()))
+{
+}
+
+HostLoad::~HostLoad() = default;
+
+void HostLoad::update()
+{
+ double now = surf_get_clock();
+ if (last_updated < now) {
+ /* Current flop per second computed by the cpu; current_flops = k * pstate_speed_in_flops, k \in {0, 1, ..., cores}
+ * number of active cores */
+ current_flops = lmm_constraint_get_usage(host->pimpl_cpu->constraint());
+
+ /* flops == pstate_speed * cores_being_currently_used */
+ computed_flops += (now - last_updated) * current_flops;
+ last_updated = now;
+ }
+}
+
+double HostLoad::getCurrentLoad()
+{
+ return current_flops / (host->speed() * host->coreCount());
+}
+
+double HostLoad::getComputedFlops()
+{
+ update();
+
+ return computed_flops;
+}
+
+/*
+ * Resets the counters
+ */
+void HostLoad::reset()
+{
+ last_updated = surf_get_clock();
+ computed_flops = 0;
+}
+}
+}
+
+using simgrid::plugin::HostLoad;
+
+/* **************************** events callback *************************** */
+static void on_host_added(simgrid::s4u::Host& host)
+{
+ if (dynamic_cast<simgrid::s4u::VirtualMachine*>(&host)) // Ignore virtual machines
+ return;
+ host.extension_set(new HostLoad(&host));
+}
+
+/* This callback is fired either when the host changes its state (on/off) or its speed
+ * (because the user changed the pstate, or because of external trace events) */
+static void onHostChange(simgrid::s4u::Host& host)
+{
+ if (dynamic_cast<simgrid::s4u::VirtualMachine*>(&host)) // Ignore virtual machines
+ return;
+
+ HostLoad* host_load = host.extension<HostLoad>();
+ host_load->update();
+}
+
+/* This callback is called when an action (computation, idle, ...) terminates */
+static void onActionStateChange(simgrid::surf::CpuAction* action, simgrid::surf::Action::State previous)
+{
+ for (simgrid::surf::Cpu* cpu : action->cpus()) {
+ simgrid::s4u::Host* host = cpu->getHost();
+
+ if (host == nullptr)
+ continue;
+
+ // Get the host_load extension for the relevant host
+ HostLoad* host_load = host->extension<HostLoad>();
+ host_load->update();
+ }
+}
+
+/* **************************** Public interface *************************** */
+SG_BEGIN_DECL()
+
+/** \ingroup SURF_plugin_load
+ * \brief Initializes the HostLoad plugin
+ * \details The HostLoad plugin provides an API to get the current load of each host.
+ */
+void sg_host_load_plugin_init()
+{
+ if (HostLoad::EXTENSION_ID.valid())
+ return;
+
+ HostLoad::EXTENSION_ID = simgrid::s4u::Host::extension_create<HostLoad>();
+
+ simgrid::s4u::Host::onCreation.connect(&on_host_added);
+ simgrid::surf::CpuAction::onStateChange.connect(&onActionStateChange);
+ simgrid::s4u::Host::onStateChange.connect(&onHostChange);
+ simgrid::s4u::Host::onSpeedChange.connect(&onHostChange);
+}
+
+/** @brief Returns the current load of the host passed as argument
+ *
+ * See also @ref SURF_plugin_load
+ */
+double sg_host_get_current_load(sg_host_t host)
+{
+ xbt_assert(HostLoad::EXTENSION_ID.valid(),
+ "The Load plugin is not active. Please call sg_host_load_plugin_init() during initialization.");
+
+ return host->extension<HostLoad>()->getCurrentLoad();
+}
+
+double sg_host_get_computed_flops(sg_host_t host)
+{
+ xbt_assert(HostLoad::EXTENSION_ID.valid(),
+ "The Load plugin is not active. Please call sg_host_load_plugin_init() during initialization.");
+
+ return host->extension<HostLoad>()->getComputedFlops();
+}
+
+void sg_host_load_reset(sg_host_t host)
+{
+ xbt_assert(HostLoad::EXTENSION_ID.valid(),
+ "The Load plugin is not active. Please call sg_host_load_plugin_init() during initialization.");
+
+ host->extension<HostLoad>()->reset();
+}
+
+SG_END_DECL()
