NoC cost weighting factors add up to 1

Author: soheilshahrouz

vpr/src/base/vpr_types.h

@@ -1496,6 +1496,7 @@ struct t_noc_opts {
     std::string noc_flows_file;               ///<name of the file that contains all the traffic flow information to be sent over the NoC in this design
     std::string noc_routing_algorithm;        ///<controls the routing algorithm used to route packets within the NoC
     double noc_placement_weighting;           ///<controls the significance of the NoC placement cost relative to the total placement cost range:[0-inf)
+    double noc_aggregate_bandwidth_weighting;
     double noc_latency_constraints_weighting; ///<controls the significance of meeting the traffic flow contraints range:[0-inf)
     double noc_latency_weighting;             ///<controls the significance of the traffic flow latencies relative to the other NoC placement costs range:[0-inf)
     double noc_congestion_weighting;          ///<controls the significance of the link congestions relative to the other NoC placement costs range:[0-inf)

vpr/src/place/noc_place_utils.cpp

@@ -586,6 +586,17 @@ double calculate_link_congestion_cost(const NocLink& link) {
     return congested_bw_ratio;
 }
 
+void normalize_noc_cost_weighting_factor(t_noc_opts& noc_opts) {
+
+    double weighting_factor_sum = noc_opts.noc_latency_weighting +
+                                  noc_opts.noc_latency_constraints_weighting +
+                                  noc_opts.noc_congestion_weighting;
+
+    VTR_ASSERT(weighting_factor_sum <= 1.0 && weighting_factor_sum >= 0.0);
+
+    noc_opts.noc_aggregate_bandwidth_weighting = 1.0 - weighting_factor_sum;
+}
+
 double calculate_noc_cost(const NocCostTerms& cost_terms,
                           const NocCostTerms& norm_factors,
                           const t_noc_opts& noc_opts) {
@@ -597,8 +608,8 @@ double calculate_noc_cost(const NocCostTerms& cost_terms,
      * 3) Link congestion costs
      */
     cost = noc_opts.noc_placement_weighting * (
-               cost_terms.aggregate_bandwidth * norm_factors.aggregate_bandwidth +
-               cost_terms.latency * norm_factors.latency * noc_opts.noc_latency_constraints_weighting +
+               cost_terms.aggregate_bandwidth * norm_factors.aggregate_bandwidth * noc_opts.noc_aggregate_bandwidth_weighting +
+               cost_terms.latency * norm_factors.latency * noc_opts.noc_latency_weighting +
                cost_terms.latency_overrun * norm_factors.latency_overrun * noc_opts.noc_latency_constraints_weighting +
                cost_terms.congestion * norm_factors.congestion * noc_opts.noc_congestion_weighting);
 

vpr/src/place/noc_place_utils.h

@@ -395,6 +395,8 @@ std::pair<double, double> calculate_traffic_flow_latency_cost(const std::vector<
  */
 double calculate_link_congestion_cost(const NocLink& link);
 
+void normalize_noc_cost_weighting_factor(t_noc_opts& noc_opts);
+
 /**
  * @brief Computes a weighted average of NoC cost term to determine
  * NoC's contribution to the total placement cost.

vpr/src/place/place.cpp

@@ -656,6 +656,10 @@ void try_place(const Netlist<>& net_list,
 
     vtr::ScopedStartFinishTimer timer("Placement");
 
+    if (noc_opts.noc) {
+        normalize_noc_cost_weighting_factor(const_cast<t_noc_opts&>(noc_opts));
+    }
+
     initial_placement(placer_opts,
                       placer_opts.constraints_file.c_str(),
                       noc_opts);