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 auto insert_done = host_rates_.insert(std::make_pair(host->get_name(), rate_level));
32 if (not insert_done.second)
33 insert_done.first->second = rate_level;
35 // Each time we add a host, we refresh the decay model
36 refresh_decay_bandwidths();
39 double WifiLinkImpl::get_host_rate(const s4u::Host* host) const
41 auto host_rates_it = host_rates_.find(host->get_name());
43 if (host_rates_it == host_rates_.end())
46 int rate_id = host_rates_it->second;
47 xbt_assert(rate_id >= 0,
48 "Negative host wifi rate levels are invalid but host '%s' uses %d as a rate level on link '%s'",
49 host->get_cname(), rate_id, this->get_cname());
50 xbt_assert(rate_id < (int)bandwidths_.size(),
51 "Link '%s' only has %zu wifi rate levels, so the provided level %d is invalid for host '%s'.",
52 this->get_cname(), bandwidths_.size(), rate_id, host->get_cname());
54 Metric rate = use_decay_model_ ? decay_bandwidths_[rate_id] : bandwidths_[rate_id];
55 return rate.peak * rate.scale;
58 s4u::Link::SharingPolicy WifiLinkImpl::get_sharing_policy() const
60 return s4u::Link::SharingPolicy::WIFI;
63 size_t WifiLinkImpl::get_host_count() const
65 return host_rates_.size();
68 void WifiLinkImpl::refresh_decay_bandwidths()
70 // Compute number of STAtion on the Access Point
71 size_t nSTA = get_host_count();
73 std::vector<Metric> new_bandwidths;
74 for (auto const& bandwidth : bandwidths_) {
75 // Instantiate decay model relatively to the actual bandwidth
76 double max_bw = bandwidth.peak;
77 double min_bw = bandwidth.peak - (wifi_max_rate_ - wifi_min_rate_);
78 double model_rate = bandwidth.peak - (wifi_max_rate_ - model_rate_);
80 double N0 = max_bw - min_bw;
81 double lambda = (-log(model_rate - min_bw) + log(N0)) / model_n_;
82 // Since decay model start at 0 we should use (nSTA-1)
83 double new_peak = N0 * exp(-lambda * (nSTA - 1)) + min_bw;
84 new_bandwidths.push_back({new_peak, 1.0, nullptr});
86 decay_bandwidths_ = new_bandwidths;
89 bool WifiLinkImpl::toggle_decay_model()
91 use_decay_model_ = not use_decay_model_;
92 return use_decay_model_;
95 void WifiLinkImpl::set_latency(double value)
97 xbt_assert(value == 0, "Latency cannot be set for WiFi Links.");
99 } // namespace resource
100 } // namespace kernel
101 } // namespace simgrid