1 /* Copyright (c) 2017-2018. 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 /* Parallel tasks are convenient abstractions of parallel computational kernels that span over several machines.
7 * To create a new one, you have to provide several things:
8 * - a vector of hosts on which the task will execute
9 * - a vector of values, the amount of computation for each of the hosts (in flops)
10 * - a matrix of values, the amount of communication between each pair of hosts (in bytes)
12 * Each of these operation will be processed at the same relative speed.
13 * This means that at some point in time, all sub-executions and all sub-communications will be at 20% of completion.
14 * Also, they will all complete at the exact same time.
16 * This is obviously a simplistic abstraction, but this is very handful in a large amount of situations.
18 * Please note that you must have the LV07 platform model enabled to use such constructs.
21 #include "simgrid/plugins/energy.h"
22 #include <simgrid/s4u.hpp>
24 XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_energyptask, "Messages specific for this s4u example");
28 /* Retrieve the list of all hosts as an array of hosts */
29 std::vector<simgrid::s4u::Host*> hosts = simgrid::s4u::Engine::get_instance()->get_all_hosts();
30 int hosts_count = hosts.size();
32 XBT_INFO("First, build a classical parallel task, with 1 Gflop to execute on each node, "
33 "and 10MB to exchange between each pair");
34 double* computation_amounts = new double[hosts_count]();
35 double* communication_amounts = new double[hosts_count * hosts_count]();
37 for (int i = 0; i < hosts_count; i++)
38 computation_amounts[i] = 1e9; // 1 Gflop
40 for (int i = 0; i < hosts_count; i++)
41 for (int j = i + 1; j < hosts_count; j++)
42 communication_amounts[i * hosts_count + j] = 1e7; // 10 MB
44 simgrid::s4u::this_actor::parallel_execute(hosts_count, hosts.data(), computation_amounts, communication_amounts);
46 XBT_INFO("We can do the same with a timeout of one second enabled.");
47 computation_amounts = new double[hosts_count]();
48 communication_amounts = new double[hosts_count * hosts_count]();
50 for (int i = 0; i < hosts_count; i++)
51 computation_amounts[i] = 1e9; // 1 Gflop
53 for (int i = 0; i < hosts_count; i++)
54 for (int j = i + 1; j < hosts_count; j++)
55 communication_amounts[i * hosts_count + j] = 1e7; // 10 MB
58 simgrid::s4u::this_actor::parallel_execute(hosts_count, hosts.data(), computation_amounts, communication_amounts,
59 1.0 /* timeout (in seconds)*/);
60 XBT_WARN("Woops, this did not timeout as expected... Please report that bug.");
62 /* Do nothing this exception on timeout was expected */
63 XBT_DEBUG("Caught expected exception: %s", e.what());
66 XBT_INFO("Then, build a parallel task involving only computations and no communication (1 Gflop per node)");
67 computation_amounts = new double[hosts_count]();
68 for (int i = 0; i < hosts_count; i++)
69 computation_amounts[i] = 1e9; // 1 Gflop
70 simgrid::s4u::this_actor::parallel_execute(hosts_count, hosts.data(), computation_amounts, nullptr /* no comm */);
72 XBT_INFO("Then, build a parallel task involving only heterogeneous computations and no communication");
73 computation_amounts = new double[hosts_count]();
74 for (int i = 0; i < hosts_count; i++)
75 computation_amounts[i] = 5 * (i + 1) * 1e8; // 500Mflop, 1Gflop, 1.5Gflop
76 simgrid::s4u::this_actor::parallel_execute(hosts_count, hosts.data(), computation_amounts, nullptr /* no comm */);
78 XBT_INFO("Then, build a parallel task with no computation nor communication (synchro only)");
79 computation_amounts = new double[hosts_count]();
80 communication_amounts = new double[hosts_count * hosts_count]();
81 simgrid::s4u::this_actor::parallel_execute(hosts_count, hosts.data(), computation_amounts, communication_amounts);
83 XBT_INFO("Finally, trick the ptask to do a 'remote execution', on host %s", hosts[1]->get_cname());
84 computation_amounts = new double[1]{1e9};
86 simgrid::s4u::Host* remote[] = {hosts[1]};
87 simgrid::s4u::this_actor::parallel_execute(1, remote, computation_amounts, nullptr);
89 XBT_INFO("Goodbye now!");
92 int main(int argc, char* argv[])
94 simgrid::s4u::Engine e(&argc, argv);
96 xbt_assert(argc <= 3, "1Usage: %s <platform file> [--energy]", argv[0]);
97 xbt_assert(argc >= 2, "2Usage: %s <platform file> [--energy]", argv[0]);
99 if (argc == 3 && argv[2][2] == 'e')
100 sg_host_energy_plugin_init();
102 e.load_platform(argv[1]);
104 /* Pick a process, no matter which, from the platform file */
105 simgrid::s4u::Actor::create("test", simgrid::s4u::Host::by_name("MyHost1"), runner);
108 XBT_INFO("Simulation done.");