X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/84402e8e2ee2a2d0bef25fdceb0a263ed8b471f6..2dab73b61a6ad4feb7d2d267bf5621c7b95926b3:/src/surf/network_wifi.cpp

diff --git a/src/surf/network_wifi.cpp b/src/surf/network_wifi.cpp
index 7a0896ee61..29d1c5f330 100644
--- a/src/surf/network_wifi.cpp
+++ b/src/surf/network_wifi.cpp
@@ -32,6 +32,9 @@ void NetworkWifiLink::set_host_rate(const s4u::Host* host, int rate_level)
   auto insert_done = host_rates_.insert(std::make_pair(host->get_name(), rate_level));
   if (insert_done.second == false)
     insert_done.first->second = rate_level;
+
+  // Each time we add a host, we refresh the decay model
+  refresh_decay_bandwidths();
 }
 
 double NetworkWifiLink::get_host_rate(const s4u::Host* host)
@@ -46,7 +49,7 @@ double NetworkWifiLink::get_host_rate(const s4u::Host* host)
   xbt_assert(rate_id >= 0 && rate_id < (int)bandwidths_.size(), "Host '%s' has an invalid rate '%d' on wifi link '%s'",
              host->get_name().c_str(), rate_id, this->get_cname());
 
-  Metric rate = bandwidths_[rate_id];
+  Metric rate = use_decay_model_ ? decay_bandwidths_[rate_id] : bandwidths_[rate_id];
   return rate.peak * rate.scale;
 }
 
@@ -55,6 +58,35 @@ s4u::Link::SharingPolicy NetworkWifiLink::get_sharing_policy()
   return s4u::Link::SharingPolicy::WIFI;
 }
 
+void NetworkWifiLink::refresh_decay_bandwidths(){
+  // Compute number of STAtion on the Access Point
+  int nSTA=host_rates_.size();
+    
+  std::vector<Metric> new_bandwidths;
+  for (auto bandwidth : bandwidths_){
+    // Instanciate decay model relatively to the actual bandwidth
+    double max_bw=bandwidth.peak;
+    double min_bw=bandwidth.peak-(wifi_max_rate_-wifi_min_rate_);
+    double model_rate=bandwidth.peak-(wifi_max_rate_-model_rate_);
+
+    xbt_assert(min_bw > 0, "Your WIFI link is using bandwidth(s) which is too low for the decay model.");
+
+    double N0=max_bw-min_bw;
+    double lambda=(-log(model_rate-min_bw)+log(N0))/model_n_;
+    // Since decay model start at 0 we should use (nSTA-1)
+    double new_peak=N0*exp(-lambda*(nSTA-1))+min_bw;
+    new_bandwidths.push_back({new_peak, 1.0, nullptr});
+
+  }
+  decay_bandwidths_=new_bandwidths;
+}
+
+bool NetworkWifiLink::toggle_decay_model(){
+  use_decay_model_=!use_decay_model_;
+  return(use_decay_model_);
+}
+
+  
 } // namespace resource
 } // namespace kernel
 } // namespace simgrid