1 /* Copyright (c) 2009-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 /* simple test to schedule a DAX file with the Min-Min algorithm. */
8 #include <simgrid/host.h>
9 #include <simgrid/s4u.hpp>
12 XBT_LOG_NEW_DEFAULT_CATEGORY(dag_scheduling, "Logging specific to this example");
13 namespace sg4 = simgrid::s4u;
15 static std::vector<sg4::Exec*> get_ready_tasks(const std::vector<sg4::ActivityPtr>& dax)
17 std::vector<sg4::Exec*> ready_tasks;
18 std::map<sg4::Exec*, unsigned int> candidate_execs;
21 // Only look at activity that have their dependencies solved but are not assigned
22 if (a->dependencies_solved() && not a->is_assigned()) {
23 // if it is an exec, it's ready
24 if (auto* exec = dynamic_cast<sg4::Exec*>(a.get()))
25 ready_tasks.push_back(exec);
26 // if it a comm, we consider its successor as a candidate. If a candidate solves all its dependencies,
27 // i.e., get all its input data, it's ready
28 if (const auto* comm = dynamic_cast<sg4::Comm*>(a.get())) {
29 auto* next_exec = static_cast<sg4::Exec*>(comm->get_successors().front().get());
30 candidate_execs[next_exec]++;
31 if (next_exec->get_dependencies().size() == candidate_execs[next_exec])
32 ready_tasks.push_back(next_exec);
36 XBT_DEBUG("There are %zu ready tasks", ready_tasks.size());
40 static sg4::Host* get_best_host(const sg4::ExecPtr exec, double* min_finish_time)
42 sg4::Host* best_host = nullptr;
43 *min_finish_time = std::numeric_limits<double>::max();
45 for (const auto& host : sg4::Engine::get_instance()->get_all_hosts()) {
46 double data_available = 0.;
47 double last_data_available = -1.0;
48 /* compute last_data_available */
49 for (const auto& parent : exec->get_dependencies()) {
51 if (const auto* comm = dynamic_cast<sg4::Comm*>(parent.get())) {
52 auto source = comm->get_source();
53 XBT_DEBUG("transfer from %s to %s", source->get_cname(), host->get_cname());
54 /* Estimate the redistribution time from this parent */
56 if (comm->get_remaining() <= 1e-6) {
59 double bandwidth = std::numeric_limits<double>::max();
60 auto [links, latency] = source->route_to(host);
61 for (auto const& link : links)
62 bandwidth = std::min(bandwidth, link->get_bandwidth());
64 redist_time = latency + comm->get_remaining() / bandwidth;
66 // We use the user data field to store the finish time of the predecessor of the comm, i.e., its potential
68 data_available = *comm->get_data<double>() + redist_time;
71 /* no transfer, control dependency */
72 if (const auto* exec = dynamic_cast<sg4::Exec*>(parent.get()))
73 data_available = exec->get_finish_time();
75 if (last_data_available < data_available)
76 last_data_available = data_available;
79 double finish_time = std::max(*host->get_data<double>(), last_data_available) +
80 exec->get_remaining() / host->get_speed();
82 XBT_DEBUG("%s finishes on %s at %f", exec->get_cname(), host->get_cname(), finish_time);
84 if (finish_time < *min_finish_time) {
85 *min_finish_time = finish_time;
93 static void schedule_on(sg4::ExecPtr exec, sg4::Host* host, double busy_until = 0.0)
96 // We use the user data field to store up to when the host is busy
97 delete host->get_data<double>(); // In case we're erasing a previous value
98 host->set_data(new double(busy_until));
99 // we can also set the destination of all the input comms of this exec
100 for (const auto& pred : exec->get_dependencies()) {
101 auto* comm = dynamic_cast<sg4::Comm*>(pred.get());
102 if (comm != nullptr) {
103 comm->set_destination(host);
104 delete comm->get_data<double>();
107 // we can also set the source of all the output comms of this exec
108 for (const auto& succ : exec->get_successors()) {
109 auto* comm = dynamic_cast<sg4::Comm*>(succ.get());
111 comm->set_source(host);
115 int main(int argc, char** argv)
117 sg4::Engine e(&argc, argv);
118 std::set<sg4::Activity*> vetoed;
119 e.track_vetoed_activities(&vetoed);
121 sg4::Activity::on_completion_cb([](sg4::Activity const& activity) {
122 // when an Exec completes, we need to set the potential start time of all its ouput comms
123 const auto* exec = dynamic_cast<sg4::Exec const*>(&activity);
124 if (exec == nullptr) // Only Execs are concerned here
126 for (const auto& succ : exec->get_successors()) {
127 auto* comm = dynamic_cast<sg4::Comm*>(succ.get());
128 if (comm != nullptr) {
129 auto* finish_time = new double(exec->get_finish_time());
130 // We use the user data field to store the finish time of the predecessor of the comm, i.e., its potential start
132 comm->set_data(finish_time);
137 e.load_platform(argv[1]);
139 /* Mark all hosts as sequential, as it ought to be in such a scheduling example.
141 * It means that the hosts can only compute one thing at a given time. If an execution already takes place on a given
142 * host, any subsequently started execution will be queued until after the first execution terminates */
143 for (auto const& host : e.get_all_hosts()) {
144 host->set_concurrency_limit(1);
145 host->set_data(new double(0.0));
147 /* load the DAX file */
148 auto dax = sg4::create_DAG_from_DAX(argv[2]);
150 /* Schedule the root first */
152 auto* root = static_cast<sg4::Exec*>(dax.front().get());
153 auto host = get_best_host(root, &finish_time);
154 schedule_on(root, host);
158 while (not vetoed.empty()) {
159 XBT_DEBUG("Start new scheduling round");
160 /* Get the set of ready tasks */
161 auto ready_tasks = get_ready_tasks(dax);
164 if (ready_tasks.empty()) {
165 /* there is no ready exec, let advance the simulation */
169 /* For each ready exec:
170 * get the host that minimizes the completion time.
171 * select the exec that has the minimum completion time on its best host.
173 double min_finish_time = std::numeric_limits<double>::max();
174 sg4::Exec* selected_task = nullptr;
175 sg4::Host* selected_host = nullptr;
177 for (auto exec : ready_tasks) {
178 XBT_DEBUG("%s is ready", exec->get_cname());
180 host = get_best_host(exec, &finish_time);
181 if (finish_time < min_finish_time) {
182 min_finish_time = finish_time;
183 selected_task = exec;
184 selected_host = host;
188 XBT_INFO("Schedule %s on %s", selected_task->get_cname(), selected_host->get_cname());
189 schedule_on(selected_task, selected_host, min_finish_time);
196 for (auto const& h : e.get_all_hosts())
197 delete h->get_data<double>();
199 XBT_INFO("Simulation Time: %f", simgrid_get_clock());