-/* Copyright (c) 2017-2019. The SimGrid Team. All rights reserved. */
+/* Copyright (c) 2017-2020. 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 tasks are convenient abstractions of parallel computational kernels that span over several machines.
+/* 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 task will execute
+ * - 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)
*
auto hosts = simgrid::s4u::Engine::get_instance()->get_all_hosts();
size_t hosts_count = hosts.size();
- XBT_INFO("First, build a classical parallel task, with 1 Gflop to execute on each node, "
- "and 10MB to exchange between each pair");
-
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++)
}
/* ------[ test 3 ]----------------- */
- XBT_INFO("Then, build a parallel task involving only computations (of different amounts) and no communication");
- computation_amounts = {3e8, 6e8, 1e9}; // 300Mflop, 6Mflop, 1Gflop
+ 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 task with no computation nor communication (synchro only)");
+ 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!");
}
