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/* Copyright (c) 2010-2025. 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. */
/* This example shows how to simulate a non-linear resource sharing for
* CPUs.
*/
#include <simgrid/s4u.hpp>
namespace sg4 = simgrid::s4u;
XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_test, "Messages specific for this s4u example");
/*************************************************************************************************/
static void runner()
{
double computation_amount = sg4::this_actor::get_host()->get_speed();
int n_task = 10;
std::vector<sg4::ExecPtr> tasks;
XBT_INFO(
"Execute %d tasks of %g flops, should take %d second in a CPU without degradation. It will take the double here.",
n_task, computation_amount, n_task);
for (int i = 0; i < n_task; i++) {
tasks.emplace_back(sg4::this_actor::exec_async(computation_amount));
}
XBT_INFO("Waiting for all tasks to be done!");
for (const auto& task : tasks)
task->wait();
XBT_INFO("Finished executing. Goodbye now!");
}
/*************************************************************************************************/
/** @brief Non-linear resource sharing for CPU */
static double cpu_nonlinear(const sg4::Host* host, double capacity, int n)
{
/* emulates a degradation in CPU according to the number of tasks
* totally unrealistic but for learning purposes */
capacity = n > 1 ? capacity / 2 : capacity;
XBT_INFO("Host %s, %d concurrent tasks, new capacity %lf", host->get_cname(), n, capacity);
return capacity;
}
/** @brief Create a simple 1-host platform */
static void load_platform(sg4::Engine& e)
{
auto* zone = e.get_netzone_root();
auto* runner_host = zone->add_host("runner", 1e6);
runner_host->set_sharing_policy(sg4::Host::SharingPolicy::NONLINEAR,
std::bind(&cpu_nonlinear, runner_host, std::placeholders::_1, std::placeholders::_2));
runner_host->seal();
zone->seal();
/* create actor runner */
e.add_actor("runner", runner_host, runner);
}
/*************************************************************************************************/
int main(int argc, char* argv[])
{
sg4::Engine e(&argc, argv);
/* create platform */
load_platform(e);
/* runs the simulation */
e.run();
return 0;
}
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