+++ /dev/null
-/* Copyright (c) 2006-2018. 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 <algorithm>
-#include <map>
-#include <unordered_map>
-#include <queue>
-
-#include <boost/heap/fibonacci_heap.hpp>
-#include <simgrid/plugins/load.h>
-#include <src/smpi/plugins/load_balancer/load_balancer.hpp>
-
-XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(plugin_load_balancer);
-
-namespace simgrid {
-namespace plugin {
-namespace loadbalancer {
-
-class XBT_PRIVATE compare_hosts {
-public:
- bool operator()(simgrid::s4u::Host* const a, simgrid::s4u::Host* const b) const;
-};
-
-typedef boost::heap::fibonacci_heap<simgrid::s4u::Host*, boost::heap::compare<compare_hosts>>::handle_type heap_handle;
-
-/**
- * Structure that imitates a std::pair, but it allows us
- * to use meaningful names instead of .first and .second
- */
-struct XBT_PRIVATE pair_handle_load
-{
- heap_handle update_handle;
- double load;
-};
-
-static std::map<simgrid::s4u::Host* const, pair_handle_load> additional_load;
-
-bool compare_hosts::operator()(simgrid::s4u::Host* const a, simgrid::s4u::Host* const b) const {
- return additional_load[a].load > additional_load[b].load;
-}
-
-
-LoadBalancer::LoadBalancer()
-{
-}
-
-LoadBalancer::~LoadBalancer()
-{
-}
-
-void LoadBalancer::run()
-{
- simgrid::s4u::Engine* engine = simgrid::s4u::Engine::get_instance();
- std::vector<simgrid::s4u::Host*> available_hosts = engine->get_filtered_hosts([](simgrid::s4u::Host* host) {
- return not host->is_off();
- });
- xbt_assert(available_hosts.size() > 0, "No hosts available; are they all switched off?");
-
- // TODO: Account for daemon background load (-> use especially the availability file)
-
- std::vector<simgrid::s4u::ActorPtr> all_actors =
- engine->get_filtered_actors([](simgrid::s4u::ActorPtr actor) { return not actor->is_daemon(); });
-
- for (auto& actor : all_actors) {
- new_mapping.assign(actor, actor->get_host());
- }
- // Sort the actors, from highest to lowest load; we then just iterate over these actors
- std::sort(all_actors.begin(), all_actors.end(), [this](simgrid::s4u::ActorPtr a, simgrid::s4u::ActorPtr b) {
- return actor_computation[a->get_pid()] > actor_computation[b->get_pid()];
- });
-
- // Sort the hosts. Use a heap datastructure, because we have to reorder
- // after a host got another actor assigned (or moved from).
- // We can't use std::priorityQueue here because we modify *two* elements: The top element, which
- // we can access and which has the lowest load, gets a new actor assigned.
- // However, the host loosing that actor must be updated as well.
- // std::priorityQueue is immutable and hence doesn't work for us.
- //
- // This heap contains the least loaded host at the top
- boost::heap::fibonacci_heap<simgrid::s4u::Host*, boost::heap::compare<compare_hosts>> usable_hosts;
- for (auto& host : available_hosts) {
- std::vector<simgrid::s4u::ActorPtr> actors = host->get_all_actors();
- heap_handle update_handle = usable_hosts.push(host); // Required to update elements in the heap
- additional_load[host] = {update_handle, 0}; // Save the handle for later
- const double total_flops_computed = sg_host_get_computed_flops(host);
- for (auto& actor : actors) {
- additional_load[host].load += actor_computation[actor->get_pid()] / total_flops_computed; // Normalize load - this allows comparison
- // even between hosts with different frequencies
- XBT_DEBUG("Actor %li -> %f", actor->get_pid(), actor_computation[actor->get_pid()]);
- }
- usable_hosts.increase(update_handle);
- XBT_DEBUG("Host %s initialized to %f", host->get_cname(), additional_load[host].load);
- }
-
- // Implementation of the Greedy algorithm
- for (auto& actor : all_actors) {
- simgrid::s4u::Host* target_host = usable_hosts.top(); // This is the host with the lowest load
-
- simgrid::s4u::Host* cur_mapped_host = new_mapping.get_host(actor);
- if (target_host != cur_mapped_host
- && additional_load[target_host].load + actor_computation[actor->get_pid()] < additional_load[cur_mapped_host].load
- && new_mapping.count_actors(cur_mapped_host) > 1) {
- usable_hosts.pop();
- XBT_DEBUG("Assigning %li from %s to %s -- actor_load: %f -- host_load: %f", actor->get_pid(), actor->get_host()->get_cname(), target_host->get_cname(), actor_computation[actor->get_pid()], additional_load[target_host].load);
- additional_load[cur_mapped_host].load = std::max<double>(0.0, additional_load[cur_mapped_host].load - actor_computation[actor->get_pid()]); // No negative loads, please!
- usable_hosts.update(additional_load[cur_mapped_host].update_handle, cur_mapped_host);
- additional_load[target_host].load += actor_computation[actor->get_pid()];
-
- new_mapping.assign(actor, target_host);
-
- XBT_DEBUG("Assigning actor %li to host %s", actor->get_pid(), target_host->get_cname());
-
- XBT_DEBUG("host_load: %f after the assignment", additional_load[target_host].load);
- additional_load[target_host].update_handle = usable_hosts.push(target_host); // Save update handle for later
- }
- }
-
- while (!usable_hosts.empty()) {
- simgrid::s4u::Host* host = usable_hosts.top();
- usable_hosts.pop();
-
- sg_host_load_reset(host); // Reset host load for next iterations
-
- if (XBT_LOG_ISENABLED(plugin_load_balancer, e_xbt_log_priority_t::xbt_log_priority_debug)) {
- /* Debug messages that allow us to verify the load for each host */
- XBT_DEBUG("Host: %s, load total: %f", host->get_cname(), additional_load[host].load);
- double load_verif = 0.0;
- new_mapping.for_each_actor(host,
- [this, &load_verif](simgrid::s4u::ActorPtr actor) {
- load_verif += actor_computation[actor->get_pid()];
- XBT_DEBUG(" %li (load: %f)", actor->get_pid(), actor_computation[actor->get_pid()]);
- });
- XBT_DEBUG("Host load verification: %f", load_verif);
- }
- }
- for (auto& elem : actor_computation) { // Reset actor load
- elem.second = 0;
- }
-}
-
-simgrid::s4u::Host* LoadBalancer::get_mapping(simgrid::s4u::ActorPtr actor)
-{
- return new_mapping.get_host(actor);
-}
-
-void LoadBalancer::record_actor_computation(simgrid::s4u::ActorPtr actor, double load)
-{
- actor_computation[actor->get_pid()] += load;
-}
-}
-}
-}
