1 /* Copyright (c) 2019-2022. 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 #include <simgrid/s4u/Host.hpp>
8 #include "src/kernel/resource/WifiLinkImpl.hpp"
9 #include "src/surf/surf_interface.hpp"
11 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(res_network);
21 WifiLinkImpl::WifiLinkImpl(const std::string& name, const std::vector<double>& bandwidths, lmm::System* system)
22 : StandardLinkImpl(name)
24 this->set_constraint(system->constraint_new(this, 1));
25 for (auto bandwidth : bandwidths)
26 bandwidths_.push_back({bandwidth, 1.0, nullptr});
29 void WifiLinkImpl::set_host_rate(const s4u::Host* host, int rate_level)
31 host_rates_[host->get_name()] = rate_level;
33 // Each time we add a host, we refresh the decay model
34 refresh_decay_bandwidths();
37 double WifiLinkImpl::get_host_rate(const s4u::Host* host) const
39 auto host_rates_it = host_rates_.find(host->get_name());
41 if (host_rates_it == host_rates_.end())
44 int rate_id = host_rates_it->second;
45 xbt_assert(rate_id >= 0,
46 "Negative host wifi rate levels are invalid but host '%s' uses %d as a rate level on link '%s'",
47 host->get_cname(), rate_id, this->get_cname());
48 xbt_assert(rate_id < (int)bandwidths_.size(),
49 "Link '%s' only has %zu wifi rate levels, so the provided level %d is invalid for host '%s'.",
50 this->get_cname(), bandwidths_.size(), rate_id, host->get_cname());
52 Metric rate = use_decay_model_ ? decay_bandwidths_[rate_id] : bandwidths_[rate_id];
53 return rate.peak * rate.scale;
56 s4u::Link::SharingPolicy WifiLinkImpl::get_sharing_policy() const
58 return s4u::Link::SharingPolicy::WIFI;
61 size_t WifiLinkImpl::get_host_count() const
63 return host_rates_.size();
66 void WifiLinkImpl::refresh_decay_bandwidths()
68 // Compute number of STAtion on the Access Point
69 const auto nSTA_minus_1 = static_cast<double>(get_host_count() - 1);
71 std::vector<Metric> new_bandwidths;
72 for (auto const& bandwidth : bandwidths_) {
73 // Instantiate decay model relatively to the actual bandwidth
74 double max_bw = bandwidth.peak;
75 double min_bw = bandwidth.peak - (wifi_max_rate_ - wifi_min_rate_);
76 double model_rate = bandwidth.peak - (wifi_max_rate_ - model_rate_);
78 double N0 = max_bw - min_bw;
79 double lambda = (-log(model_rate - min_bw) + log(N0)) / model_n_;
80 // Since decay model start at 0 we should use (nSTA-1)
81 double new_peak = N0 * exp(-lambda * nSTA_minus_1) + min_bw;
82 new_bandwidths.push_back({new_peak, 1.0, nullptr});
84 decay_bandwidths_ = new_bandwidths;
87 bool WifiLinkImpl::toggle_decay_model()
89 use_decay_model_ = not use_decay_model_;
90 return use_decay_model_;
93 void WifiLinkImpl::set_latency(double value)
95 xbt_assert(value == 0, "Latency cannot be set for WiFi Links.");
97 } // namespace resource
99 } // namespace simgrid