+++ /dev/null
-/* Copyright (c) 2017-2021. 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. */
-
-/* Parallel activities are convenient abstractions of parallel computational kernels that span over several machines.
- * To create a new one, you have to provide several things:
- * - a vector of hosts on which the activity will execute
- * - a vector of values, the amount of computation for each of the hosts (in flops)
- * - a matrix of values, the amount of communication between each pair of hosts (in bytes)
- *
- * Each of these operation will be processed at the same relative speed.
- * This means that at some point in time, all sub-executions and all sub-communications will be at 20% of completion.
- * Also, they will all complete at the exact same time.
- *
- * This is obviously a simplistic abstraction, but this is very handful in a large amount of situations.
- *
- * Please note that you must have the LV07 platform model enabled to use such constructs.
- */
-
-#include <simgrid/s4u.hpp>
-
-XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_ptask, "Messages specific for this s4u example");
-
-static void runner()
-{
- /* Retrieve the list of all hosts as an array of hosts */
- auto hosts = simgrid::s4u::Engine::get_instance()->get_all_hosts();
- size_t hosts_count = hosts.size();
-
- std::vector<double> computation_amounts;
- std::vector<double> communication_amounts;
-
- /* ------[ test 1 ]----------------- */
- XBT_INFO("First, build a classical parallel activity, with 1 Gflop to execute on each node, "
- "and 10MB to exchange between each pair");
-
- computation_amounts.assign(hosts_count, 1e9 /*1Gflop*/);
- communication_amounts.assign(hosts_count * hosts_count, 0);
- for (size_t i = 0; i < hosts_count; i++)
- for (size_t j = i + 1; j < hosts_count; j++)
- communication_amounts[i * hosts_count + j] = 1e7; // 10 MB
-
- simgrid::s4u::this_actor::parallel_execute(hosts, computation_amounts, communication_amounts);
-
- /* ------[ test 2 ]----------------- */
- XBT_INFO("We can do the same with a timeout of 10 seconds enabled.");
- computation_amounts.assign(hosts_count, 1e9 /*1Gflop*/);
- communication_amounts.assign(hosts_count * hosts_count, 0);
- for (size_t i = 0; i < hosts_count; i++)
- for (size_t j = i + 1; j < hosts_count; j++)
- communication_amounts[i * hosts_count + j] = 1e7; // 10 MB
-
- try {
- simgrid::s4u::this_actor::exec_init(hosts, computation_amounts, communication_amounts)
- ->wait_for(10.0 /* timeout (in seconds)*/);
- xbt_die("Woops, this did not timeout as expected... Please report that bug.");
- } catch (const simgrid::TimeoutException&) {
- XBT_INFO("Caught the expected timeout exception.");
- }
-
- /* ------[ test 3 ]----------------- */
- XBT_INFO("Then, build a parallel activity involving only computations (of different amounts) and no communication");
- computation_amounts = {3e8, 6e8, 1e9}; // 300Mflop, 600Mflop, 1Gflop
- communication_amounts.clear(); // no comm
- simgrid::s4u::this_actor::parallel_execute(hosts, computation_amounts, communication_amounts);
-
- /* ------[ test 4 ]----------------- */
- XBT_INFO("Then, build a parallel activity with no computation nor communication (synchro only)");
- computation_amounts.clear();
- communication_amounts.clear();
- simgrid::s4u::this_actor::parallel_execute(hosts, computation_amounts, communication_amounts);
-
- /* ------[ test 5 ]----------------- */
- XBT_INFO("Then, Monitor the execution of a parallel activity");
- computation_amounts.assign(hosts_count, 1e6 /*1Mflop*/);
- communication_amounts = {0, 1e6, 0, 0, 0, 1e6, 1e6, 0, 0};
- simgrid::s4u::ExecPtr activity =
- simgrid::s4u::this_actor::exec_init(hosts, computation_amounts, communication_amounts);
- activity->start();
-
- while (not activity->test()) {
- XBT_INFO("Remaining flop ratio: %.0f%%", 100 * activity->get_remaining_ratio());
- simgrid::s4u::this_actor::sleep_for(5);
- }
- activity->wait();
-
- /* ------[ test 6 ]----------------- */
- XBT_INFO("Finally, simulate a malleable task (a parallel execution that gets reconfigured after its start).");
- XBT_INFO(" - Start a regular parallel execution, with both comm and computation");
- computation_amounts.assign(hosts_count, 1e6 /*1Mflop*/);
- communication_amounts = {0, 1e6, 0, 0, 1e6, 0, 1e6, 0, 0};
- activity = simgrid::s4u::this_actor::exec_init(hosts, computation_amounts, communication_amounts);
- activity->start();
-
- simgrid::s4u::this_actor::sleep_for(10);
- double remaining_ratio = activity->get_remaining_ratio();
- XBT_INFO(" - After 10 seconds, %.2f%% remains to be done. Change it from 3 hosts to 2 hosts only.",
- remaining_ratio * 100);
- XBT_INFO(" Let's first suspend the task.");
- activity->suspend();
-
- XBT_INFO(" - Now, simulate the reconfiguration (modeled as a comm from the removed host to the remaining ones).");
- std::vector<double> rescheduling_comp{0, 0, 0};
- std::vector<double> rescheduling_comm{0, 0, 0, 0, 0, 0, 25000, 25000, 0};
- simgrid::s4u::this_actor::parallel_execute(hosts, rescheduling_comp, rescheduling_comm);
-
- XBT_INFO(" - Now, let's cancel the old task and create a new task with modified comm and computation vectors:");
- XBT_INFO(" What was already done is removed, and the load of the removed host is shared between remaining ones.");
- for (int i = 0; i < 2; i++) {
- // remove what we've done so far, for both comm and compute load
- computation_amounts[i] *= remaining_ratio;
- communication_amounts[i] *= remaining_ratio;
- // The work from 1 must be shared between 2 remaining ones. 1/2=50% of extra work for each
- computation_amounts[i] *= 1.5;
- communication_amounts[i] *= 1.5;
- }
- hosts.resize(2);
- computation_amounts.resize(2);
- double remaining_comm = communication_amounts[1];
- communication_amounts = {0, remaining_comm, remaining_comm, 0}; // Resizing a linearized matrix is hairly
-
- activity->cancel();
- activity = simgrid::s4u::this_actor::exec_init(hosts, computation_amounts, communication_amounts);
-
- XBT_INFO(" - Done, let's wait for the task completion");
- activity->wait();
-
- XBT_INFO("Goodbye now!");
-}
-
-int main(int argc, char* argv[])
-{
- simgrid::s4u::Engine e(&argc, argv);
-
- xbt_assert(argc == 2, "Usage: %s <platform file>", argv[0]);
-
- e.load_platform(argv[1]);
- simgrid::s4u::Actor::create("test", simgrid::s4u::Host::by_name("MyHost1"), runner);
-
- e.run();
- XBT_INFO("Simulation done.");
- return 0;
-}
