Util hpp

Makefile

@@ -50,7 +50,7 @@ VARIANT ?= baseline
 VARIANT_SRC := variant_$(VARIANT).cpp
 
 SRC := main.cpp $(VARIANT_SRC)
-HEADERS := board.hpp forces.hpp pedestrian.hpp vector2d.hpp constants.hpp social_force.hpp
+HEADERS := board.hpp forces.hpp pedestrian.hpp vector2d.hpp constants.hpp social_force.hpp util.hpp
 
 TEST_SRC := test_vector2d.cpp test_board.cpp test_forces.cpp $(VARIANT_SRC)
 TEST_TARGET := run_tests
@@ -72,6 +72,14 @@ MP4 ?= simulation.mp4  # Default visualization video output file.
 # Use RANDOM_SEED=1 to seed from std::random_device.
 RANDOM_SEED ?= 0
 
+# flopcounter enabled/disabled, no impact on runtime when running with 0
+# default = 0 = disabled
+# 1 = enabled
+# if set to 0 --> compiler will swap all function calls with ((void)0)
+# using -O3 will remove all ((void)0)
+FLOPCOUNT ?= 0
+CXXFLAGS += -DFLOPCOUNT=$(FLOPCOUNT)
+
 # Pass random-seeding mode to the C++ code.
 CXXFLAGS += -DRANDOM_SEED=$(RANDOM_SEED)
 

util.hpp

@@ -0,0 +1,116 @@
+#pragma once
+
+// This function exactly tracks the flop count for each function
+// Usage
+// compile, e.g.:
+//      make run-bench FLOPCOUNT=1 N_P=60 N_ITER=4000
+//      if not compiled with FLOPCOUNT all associated function are written as ((void)0) and removed when using -O3 flag
+// In code:
+//      FLOP_RECORD(flop_counter::<FUNC_NAME>, int add, int mult, int div, int sqrt, int exp)
+//      <FUNC_NAME> see FunctionId in util.hpp
+// Print out metrics:
+//      flop_counter::report();
+//      flop_counter::report_csv();
+// Additonal remarks:
+//      make sure to call flop_counter::reset(); after the warmup phase, because else counting flops double
+//      make sure to import util.hpp #include "util.hpp"
+
+// get the cycles count per flop
+#include "constants.hpp"   // cost_add, cost_mult, cost_div, cost_sqrt, cost_exp
+
+#include <array>
+#include <cstdint>
+#include <cstdio>
+
+#ifndef FLOPCOUNT
+#define FLOPCOUNT 0
+#endif
+
+namespace flop_counter {
+
+// defined functions, add new one if needed
+// create enumeration, which must be in sync with kFunctionNames
+enum FunctionId : int {
+  FN_W,
+  FN_ACCELERATION,
+  FN_PEDESTRIAN_REPULSION,
+  FN_OBSTACLE_REPULSION,
+  FN_NEAREST_OBSTACLE_POINT,
+  FN_UPDATE,
+  FN_OTHER,
+  FN_COUNT
+};
+
+// track the flop count for each function separately
+// add more functions, do not mix up the order
+inline constexpr std::array<const char *, FN_COUNT> kFunctionNames = {
+    "w",
+    "acceleration_term_dt",
+    "pedestrian_repulsion_dt",
+    "obstacle_repulsion_dt",
+    "find_nearest_obstacle_point",
+    "update_pass",
+    "other",
+};
+
+#if FLOPCOUNT
+
+// for each function store add, mult, div, sqrt, exp
+inline std::uint64_t counters[FN_COUNT][5]{};
+
+// update
+inline void record(FunctionId fn, std::uint64_t add, std::uint64_t mult,
+                   std::uint64_t div, std::uint64_t sqrt_n,
+                   std::uint64_t exp_n) {
+  counters[fn][0] += add;
+  counters[fn][1] += mult;
+  counters[fn][2] += div;
+  counters[fn][3] += sqrt_n;
+  counters[fn][4] += exp_n;
+}
+
+// set all metrics to 0
+inline void reset() {
+  for (int f = 0; f < FN_COUNT; ++f)
+    for (int o = 0; o < 5; ++o)
+      counters[f][o] = 0;
+}
+
+inline void report() {
+  std::printf("\n=== flop count ===\n");
+  std::printf("%-30s %12s %12s %12s %12s %12s %16s\n",
+              "function", "add", "mult", "div", "sqrt", "exp", "per function");
+  long double total = 0;
+  for (int f = 0; f < FN_COUNT; ++f) {
+    auto a = counters[f][0], m = counters[f][1], d = counters[f][2],
+         s = counters[f][3], e = counters[f][4];
+    long double w = a * (long double)cost_add  + m * (long double)cost_mult
+                  + d * (long double)cost_div  + s * (long double)cost_sqrt
+                  + e * (long double)cost_exp;
+    total += w;
+    if ((a | m | d | s | e) == 0) continue;
+    std::printf("%-30s %12llu %12llu %12llu %12llu %12llu %16.2Lf\n",
+                kFunctionNames[f],
+                (unsigned long long)a, (unsigned long long)m,
+                (unsigned long long)d, (unsigned long long)s,
+                (unsigned long long)e, w);
+  }
+  std::printf("%-30s %12s %12s %12s %12s %12s %16.2Lf\n",
+              "TOTAL", "", "", "", "", "", total);
+}
+
+#define FLOP_RECORD(fn, a, m, d, s, e) \
+  ::flop_counter::record((fn), (a), (m), (d), (s), (e))
+
+#else  // FLOPCOUNT == 0 -> no-op, removed by -O3
+
+inline void record(FunctionId, std::uint64_t, std::uint64_t, std::uint64_t,
+                   std::uint64_t, std::uint64_t) {}
+inline void reset() {}
+inline void report() {}
+
+#define FLOP_RECORD(fn, a, m, d, s, e) ((void)0)
+
+#endif
+
+}  // namespace flop_counter