[ParallelRouter] Added Timing Code for SSSP

Added code to measure the time that is spent in the SSSP loop. The
overhead added by this code should be quite small and should provide
data on how much time we are actually saving.

Author: AlexandreSinger

vpr/src/route/parallel_connection_router.cpp

@@ -1,5 +1,6 @@
 #include "parallel_connection_router.h"
 #include <algorithm>
+#include <chrono>
 #include <tuple>
 #include "router_lookahead.h"
 #include "rr_graph.h"
@@ -338,6 +339,9 @@ void ParallelConnectionRouter::timing_driven_route_connection_from_heap(RRNodeId
     this->cost_params_ = const_cast<t_conn_cost_params*>(&cost_params);
     this->bounding_box_ = const_cast<t_bb*>(&bounding_box);
 
+    // Start measuring time before the barrier
+    std::chrono::steady_clock::time_point begin_time = std::chrono::steady_clock::now();
+
     thread_barrier_.wait();
     this->timing_driven_route_connection_from_heap_thread_func(*this->sink_node_, *this->cost_params_, *this->bounding_box_, 0);
     thread_barrier_.wait();
@@ -348,6 +352,10 @@ void ParallelConnectionRouter::timing_driven_route_connection_from_heap(RRNodeId
     // Reset the heap for the next connection
     heap_.reset();
 
+    // Stop measuring time after the barrier and the heap is reset.
+    std::chrono::steady_clock::time_point end_time = std::chrono::steady_clock::now();
+    this->sssp_total_time += std::chrono::duration_cast<std::chrono::microseconds>(end_time - begin_time);
+
     // if (router_debug_) {
     //     //Update known path costs for nodes pushed but not popped, useful for debugging
     //     empty_heap_annotating_node_route_inf();

vpr/src/route/parallel_connection_router.h

@@ -1,6 +1,7 @@
 #ifndef _PARALLEL_CONNECTION_ROUTER_H
 #define _PARALLEL_CONNECTION_ROUTER_H
 
+#include <chrono>
 #include "connection_router_interface.h"
 #include "rr_graph_storage.h"
 #include "route_common.h"
@@ -162,6 +163,8 @@ class ParallelConnectionRouter : public ConnectionRouterInterface {
     ~ParallelConnectionRouter() {
         is_router_destroying_ = true;
         thread_barrier_.wait();
+
+        VTR_LOG("Parallel Connection Router is being destroyed. Time spent computing SSSP: %g seconds\n.", this->sssp_total_time.count() / 1000000.0);
     }
 
     // Clear's the modified list.  Should be called after reset_path_costs
@@ -418,6 +421,9 @@ class ParallelConnectionRouter : public ConnectionRouterInterface {
     std::atomic<RRNodeId*> sink_node_;
     std::atomic<t_conn_cost_params*> cost_params_;
     std::atomic<t_bb*> bounding_box_;
+
+    // Timing
+    std::chrono::microseconds sssp_total_time{0};
 };
 
 #endif /* _PARALLEL_CONNECTION_ROUTER_H */