Merge pull request #3161 from AlexandreSinger/feature-lookahead-profile-report

[RouterLookahead] Router Lookahead Report

Author: AlexandreSinger

doc/src/vpr/command_line_usage.rst

@@ -1840,6 +1840,17 @@ The following options are only valid when the router is in timing-driven mode (t
 
      **Default:** ``map``
 
+.. option:: --generate_router_lookahead_report {on | off}
+
+   If turned on, generates a detailed report on the router lookahead: report_router_lookahead.rpt
+
+   This report contains information on how accurate the router lookahead is and
+   if and when it overestimates the cost from a node to a target node. It does
+   this by doing a set of trial routes and comparing the estimated cost from the
+   router lookahead to the actual cost of the route path.
+
+   **Default:** ``off``
+
 .. option:: --router_initial_acc_cost_chan_congestion_threshold <float>
 
     Utilization threshold above which initial accumulated routing cost (acc_cost) is increased to penalize congested channels.

libs/librrgraph/src/base/rr_node_types.h

@@ -36,6 +36,10 @@ enum class e_rr_type : unsigned char {
 constexpr std::array<e_rr_type, (size_t)e_rr_type::NUM_RR_TYPES> RR_TYPES = {{e_rr_type::SOURCE, e_rr_type::SINK, e_rr_type::IPIN,
                                                                       e_rr_type::OPIN, e_rr_type::CHANX, e_rr_type::CHANY}};
 
+/**
+ * @brief Lookup for the string representation of the given node type. This is useful
+ *        for logging the type of an RR node.
+ */
 constexpr vtr::array<e_rr_type, const char*, (size_t)e_rr_type::NUM_RR_TYPES> rr_node_typename {"SOURCE", "SINK", "IPIN", "OPIN", "CHANX", "CHANY"};
 
 /**

vpr/src/base/SetupVPR.cpp

@@ -516,6 +516,8 @@ static void SetupRouterOpts(const t_options& Options, t_router_opts* RouterOpts)
     RouterOpts->has_choke_point = Options.router_opt_choke_points;
     RouterOpts->custom_3d_sb_fanin_fanout = Options.custom_3d_sb_fanin_fanout;
     RouterOpts->with_timing_analysis = Options.timing_analysis;
+
+    RouterOpts->generate_router_lookahead_report = Options.generate_router_lookahead_report.value();
 }
 
 static void SetupAnnealSched(const t_options& Options,

vpr/src/base/ShowSetup.cpp

@@ -383,7 +383,7 @@ static void ShowRouterOpts(const t_router_opts& RouterOpts) {
         VTR_LOG("RouterOpts.router_profiler_astar_fac: %f\n", RouterOpts.router_profiler_astar_fac);
         VTR_LOG("RouterOpts.enable_parallel_connection_router: %s\n", RouterOpts.enable_parallel_connection_router ? "true" : "false");
         VTR_LOG("RouterOpts.post_target_prune_fac: %f\n", RouterOpts.post_target_prune_fac);
-        VTR_LOG("RouterOpts.post_target_prune_offset: %f\n", RouterOpts.post_target_prune_offset);
+        VTR_LOG("RouterOpts.post_target_prune_offset: %g\n", RouterOpts.post_target_prune_offset);
         VTR_LOG("RouterOpts.multi_queue_num_threads: %d\n", RouterOpts.multi_queue_num_threads);
         VTR_LOG("RouterOpts.multi_queue_num_queues: %d\n", RouterOpts.multi_queue_num_queues);
         VTR_LOG("RouterOpts.multi_queue_direct_draining: %s\n", RouterOpts.multi_queue_direct_draining ? "true" : "false");

vpr/src/base/read_options.cpp

@@ -2936,6 +2936,16 @@ argparse::ArgumentParser create_arg_parser(const std::string& prog_name, t_optio
         .default_value("map")
         .show_in(argparse::ShowIn::HELP_ONLY);
 
+    route_timing_grp.add_argument<bool, ParseOnOff>(args.generate_router_lookahead_report, "--generate_router_lookahead_report")
+        .help("If turned on, generates a detailed report on the router lookahead: report_router_lookahead.rpt\n"
+              "\n"
+              "This report contains information on how accurate the router lookahead is and "
+              "if and when it overestimates the cost from a node to a target node. It does "
+              "this by doing a set of trial routes and comparing the estimated cost from the "
+              "router lookahead to the actual cost of the route path.")
+        .default_value("off")
+        .show_in(argparse::ShowIn::HELP_ONLY);
+
     route_timing_grp.add_argument<double>(args.router_initial_acc_cost_chan_congestion_threshold, "--router_initial_acc_cost_chan_congestion_threshold")
         .help("Utilization threshold above which initial accumulated routing cost (acc_cost) "
               "is increased to penalize congested channels. Used to bias routing away from "

vpr/src/base/read_options.h

@@ -256,6 +256,7 @@ struct t_options {
     argparse::ArgValue<int> router_debug_sink_rr;
     argparse::ArgValue<int> router_debug_iteration;
     argparse::ArgValue<e_router_lookahead> router_lookahead_type;
+    argparse::ArgValue<bool> generate_router_lookahead_report;
     argparse::ArgValue<double> router_initial_acc_cost_chan_congestion_threshold;
     argparse::ArgValue<double> router_initial_acc_cost_chan_congestion_weight;
     argparse::ArgValue<int> router_max_convergence_count;

vpr/src/base/vpr_types.h

@@ -1347,6 +1347,8 @@ struct t_router_opts {
     e_rr_node_reorder_algorithm reorder_rr_graph_nodes_algorithm = DONT_REORDER;
     int reorder_rr_graph_nodes_threshold = 0;
     int reorder_rr_graph_nodes_seed = 1;
+
+    bool generate_router_lookahead_report;
 };
 
 struct t_analysis_opts {

vpr/src/route/route.cpp

@@ -10,6 +10,7 @@
 #include "route_profiling.h"
 #include "route_utils.h"
 #include "rr_graph.h"
+#include "router_lookahead_report.h"
 #include "vtr_time.h"
 
 bool route(const Netlist<>& net_list,
@@ -152,6 +153,12 @@ bool route(const Netlist<>& net_list,
 
     VTR_ASSERT(router_lookahead != nullptr);
 
+    // After the router lookahead has been fully created, generate the router
+    // lookahead report if requested.
+    if (router_opts.generate_router_lookahead_report) {
+        generate_router_lookahead_report(router_lookahead, router_opts);
+    }
+
     /* Routing parameters */
     float pres_fac = router_opts.first_iter_pres_fac;
     update_draw_pres_fac(pres_fac); /* Typically 0 -> ignore cong. */