fix for the two main files

Makefile

@@ -63,11 +63,21 @@ endif
 
 VARIANT_SRC := ./variants/variant_$(VARIANT).cpp
 
+# symmetry variants do half the pairwise work, so they use their own main with the
+# halved flop-count formula. float_ symmetry variants use the float symmetry main.
 ifneq ($(filter float_%,$(VARIANT)),)
+ifneq ($(findstring symmetry,$(VARIANT)),)
+MAIN_SRC := main-float_symmetry.cpp
+else
 MAIN_SRC := main-float.cpp
+endif
+else
+ifneq ($(findstring symmetry,$(VARIANT)),)
+MAIN_SRC := main-symmetry.cpp
 else
 MAIN_SRC := main.cpp
 endif
+endif
 
 SRC := $(MAIN_SRC) $(VARIANT_SRC)
 HEADERS := ./headers/board.hpp ./headers/pedestrian.hpp ./headers/vector2d.hpp ./headers/constants.hpp ./headers/util.hpp
@@ -186,7 +196,7 @@ test: clean
 
 # make asm : compile and generate assembly files.
 
-ASM_CPP_SRCS := main.cpp main-float.cpp $(VARIANT_SRC)
+ASM_CPP_SRCS := main.cpp main-float.cpp main-symmetry.cpp main-float_symmetry.cpp $(VARIANT_SRC)
 ASM_HPP_SRCS := ./headers/util.hpp
 ASM_SRCS := $(ASM_CPP_SRCS) $(ASM_HPP_SRCS)
 

main-float_symmetry.cpp

@@ -0,0 +1,294 @@
+#include "./headers/board_float.hpp"
+#include "./headers/constants_float.hpp"
+#include "./headers/pedestrian_float.hpp"
+#include "./headers/social_force_float.hpp"
+
+#include <algorithm>
+#include <cstdio>
+#include <cstdlib>
+#include <vector>
+
+#ifndef BENCHMARK
+#define BENCHMARK 0
+#endif
+
+#ifndef ROOFLINE
+#define ROOFLINE 0
+#endif
+
+#ifdef __x86_64__
+#include "./headers/tsc_x86.h"
+#include <immintrin.h>
+#define TRASH_BUFFER_SIZE (16ULL * 1024 * 1024 * 2) // 2x L3 (~16MB) on the x86 machine we use for measurements
+#define PAGE_SIZE 4096
+#endif
+
+#ifdef __aarch64__
+#include "./headers/kperf.h"
+#include <arm_acle.h>
+#define TRASH_BUFFER_SIZE (1502838784ULL * 2) // 2x SLC (~1.5GB) on M3 Pro
+#define PAGE_SIZE 16384
+#endif
+
+#define N_OBSTACLES 2
+
+// Benchmark parameters (mostly copied from mvm.c in hw1)
+#define WARMUP_ITERS 3
+#define NUM_REPS 15
+#define NUM_RUNS 1
+#define CYCLES_REQUIRED 1e8
+#define MAX_NUM_RUNS (1 << 14)
+
+// Flushes caches by streaming reads through a large persistent buffer.
+long long flush_cache() {
+  static volatile char *trash_buffer = nullptr;
+  static bool initialized = false;
+
+  if (!initialized) {
+    trash_buffer = new volatile char[TRASH_BUFFER_SIZE];
+
+    // Touch one byte per page once so pages are physically mapped. And we avoid paying the cost of page faults during cache trashing below.
+    for (size_t i = 0; i < TRASH_BUFFER_SIZE; i += PAGE_SIZE) {
+      trash_buffer[i] = 1;
+    }
+
+    initialized = true;
+  }
+
+  long long acc = 0;
+
+  for (size_t i = 0; i < TRASH_BUFFER_SIZE; i += CACHE_BLOCK_SIZE) {
+    // Access one byte per cache block is enough to populate the entire block
+    acc += trash_buffer[i];
+  }
+
+#ifdef __x86_64__
+  _mm_lfence();
+#endif
+
+#ifdef __aarch64__
+  __isb(0xF);
+#endif
+
+  asm volatile("" ::: "memory");
+
+  return acc;
+}
+
+int main(int argc, const char *argv[]) {
+#ifdef __x86_64__
+  // flush denormals to zero via MXCSR. one-time, per thread.
+  // any subnormal in the j-loop chain stalls fma for 100+ cycles, this kills that.
+  _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
+  _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);
+#endif
+
+  // Check that the correct number of arguments has been passed.
+  //
+  // Expected usage:
+  //
+  //   ./main <number_of_pedestrians> <number_of_iterations> [csv_output_path]
+  //
+  // The optional third argument enables CSV dumping for visualization.
+  if (argc < 3) {
+    printf("Usage: ./main <number_of_pedestrians> <number_of_iterations> [csv_output_path]\n");
+    printf("Each iteration takes %.2f seconds in the simulation.\n", dt);
+    return 1;
+  }
+
+  // Parse command-line arguments.
+  int n_p = atoi(argv[1]);
+  int n_iter = atoi(argv[2]);
+
+  if (n_p <= 0) {
+    printf("Error: <number_of_pedestrians> must be a positive integer, got '%s'\n", argv[1]);
+    return 1;
+  }
+  if (n_iter <= 0) {
+    printf("Error: <number_of_iterations> must be a positive integer, got '%s'\n", argv[2]);
+    return 1;
+  }
+
+  // If provided, dump_path is used to write simulation states to CSV.
+  // In benchmark mode, this path is intentionally ignored to avoid measuring
+  // file I/O overhead.
+  const char *dump_path = (argc >= 4) ? argv[3] : nullptr;
+
+#if BENCHMARK
+
+#if ROOFLINE
+  volatile long long trash_value;
+#endif
+
+#ifdef __aarch64__
+  // Initialize ARM performance counters.
+  kperf_init();
+  struct performance_counters startperf, endperf;
+#endif
+
+  // Warmup runs, to bring caches, predictors, frequency to steady state. These are not measured.
+  // Each run gets a fresh initialized state because run_simulation mutates the
+  // pedestrians and board state.
+  for (int i = 0; i < WARMUP_ITERS; i++) {
+    Pedestrian *P = init_pedestrians(n_p);
+    Board board = init_board_without_obstacles();
+    run_simulation(P, board, n_p, n_iter, nullptr);
+    delete[] P;
+  }
+
+  // Calibration: finds num_runs such that one batch runs for at least
+  // CYCLES_REQUIRED cycles. A long batch keeps makes the timer and other
+  // noise overhead, negligible relative to the kernel execution cost we're
+  // actually trying to measure.
+  //
+  // Skipped when ROOFLINE is enabled: cold-cache measurements need
+  // exactly one timed simulation per batch, otherwise only the first
+  // call starts cold and subsequent calls measure warm-cache behavior.
+  // We can use large enough inputs so a single call already exceeds CYCLES_REQUIRED,
+  // when measuring for roofline plot.
+  // Note: we implemented the calibration exactly as it is done in mvm.c from hw1, we also
+  // used the same values for NUM_RUNS, etc
+  int num_runs = NUM_RUNS;
+#if !ROOFLINE
+  while (num_runs < MAX_NUM_RUNS) {
+    Pedestrian *P = init_pedestrians(n_p);
+    Board board = init_board_without_obstacles();
+
+    float cycles;
+
+#ifdef __x86_64__
+    myInt64 start = start_tsc();
+#endif
+
+#ifdef __aarch64__
+    startperf = kperf_get_counters();
+#endif
+
+    for (int j = 0; j < num_runs; j++) {
+      run_simulation(P, board, n_p, n_iter, nullptr);
+    }
+
+#ifdef __x86_64__
+    cycles = (float)stop_tsc(start);
+#endif
+
+#ifdef __aarch64__
+    endperf = kperf_get_counters();
+    cycles = (float)(endperf.cycles - startperf.cycles);
+#endif
+
+    delete[] P;
+
+    if (cycles >= CYCLES_REQUIRED)
+      break;
+    num_runs *= 2;
+  }
+#endif
+
+  // Store the cycle count of each measured repetition.
+  // The median is then used as the final timing result.
+  std::vector<float> cycles_v;
+  cycles_v.reserve(NUM_REPS);
+
+  // Measurement phase
+  for (int i = 0; i < NUM_REPS; i++) {
+    Pedestrian *P = init_pedestrians(n_p);
+    Board board = init_board_without_obstacles();
+
+#if ROOFLINE
+    trash_value = flush_cache();
+#endif
+
+#ifdef __x86_64__
+    myInt64 start = start_tsc();
+#endif
+#ifdef __aarch64__
+    startperf = kperf_get_counters();
+#endif
+
+    for (int j = 0; j < num_runs; j++) {
+      // Disable CSV dumping during benchmarking to avoid measuring file I/O
+      // overhead. Initialization is also excluded from the measured region.
+
+      run_simulation(P, board, n_p, n_iter, nullptr);
+    }
+
+#ifdef __x86_64__
+    float cycles = (float)stop_tsc(start) / num_runs;
+#endif
+#ifdef __aarch64__
+    endperf = kperf_get_counters();
+    float cycles = (float)(endperf.cycles - startperf.cycles) / num_runs;
+#endif
+
+    delete[] P;
+    cycles_v.push_back(cycles);
+  }
+
+  std::sort(cycles_v.begin(), cycles_v.end());
+  // Use the median cycle count to reduce the effect of noisy measurements.
+  float T = cycles_v[NUM_REPS / 2];
+
+#else
+
+  // Normal execution mode. If dump_path is provided, the simulation writes a CSV
+  // file that can later be used to generate a video of the simulation.
+  Pedestrian *P = init_pedestrians(n_p);
+  Board board = init_board_without_obstacles();
+  run_simulation(P, board, n_p, n_iter, dump_path);
+
+  delete[] P;
+
+#endif
+
+#if BENCHMARK
+
+  // Flop-count per simulation iteration.
+  //
+  // The total work W(n) is estimated from the number of additions,
+  // multiplications, divisions, square roots, and exponentials performed by the
+  // simulation kernels.
+
+  // symmetry: each pedestrian-pedestrian pair is computed once instead of twice,
+  // so the pairwise (n_p - 1) terms get halved -> n_p * (n_p - 1) / 2 pairs total.
+  // the self-driving force, obstacle force and update pass are untouched.
+  long long pairs = (long long)n_p * (n_p - 1) / 2;
+
+  long long add_count_per_iter = n_p * (2 + N_OBSTACLES * 10 + 2) + n_p * 7 + pairs * 14;
+  long long mult_count_per_iter = n_p * (4 + N_OBSTACLES * 13) + n_p * 16 + pairs * 24;
+  long long div_count_per_iter = n_p * (N_OBSTACLES * 1) + n_p * 2 + pairs * 1;
+  long long sqrt_count_per_iter = n_p * (N_OBSTACLES * 1) + n_p * 3 + pairs * 3;
+  long long exp_count_per_iter = n_p * (N_OBSTACLES * 1) + pairs * 1;
+
+  float W_per_iter = add_count_per_iter * cost_add + mult_count_per_iter * cost_mult + div_count_per_iter * cost_div + sqrt_count_per_iter * cost_sqrt + exp_count_per_iter * cost_exp;
+
+  // Estimated memory traffic per iteration.
+  // TODO: refine this model to account for actual memory accesses, cache reuse,
+  // and the full interaction loop.
+
+  long long Q_per_iter = sizeof(Pedestrian) * n_p + sizeof(Obstacle) * N_OBSTACLES;
+
+  // Operational intensity:
+  //
+  //   I(n) = W(n) / Q(n)
+  //
+  // where W is estimated work in flops and Q is estimated memory traffic in
+  // bytes.
+
+  float I = W_per_iter / Q_per_iter;
+  float W = W_per_iter * n_iter;
+
+  // Performance in estimated flops per cycle.
+  float P = W / T;
+
+  printf("W(n) per iteration: %.2f flops\n", W_per_iter);
+  printf("Q(n) per iteration: %lld bytes\n", Q_per_iter);
+  printf("I(n): %.2f flops/byte\n", I);
+  printf("W(n): %.2f flops\n", W);
+  printf("T(n): %.2f cycles\n", T);
+  printf("P(n): %.2f flops/cycle\n", P);
+
+#endif
+
+  return 0;
+}

main-symmetry.cpp

@@ -0,0 +1,287 @@
+#include "./headers/board.hpp"
+#include "./headers/constants.hpp"
+#include "./headers/pedestrian.hpp"
+#include "./headers/social_force.hpp"
+
+#include <algorithm>
+#include <cstdio>
+#include <cstdlib>
+#include <vector>
+
+#ifndef BENCHMARK
+#define BENCHMARK 0
+#endif
+
+#ifndef ROOFLINE
+#define ROOFLINE 0
+#endif
+
+#ifdef __x86_64__
+#include "./headers/tsc_x86.h"
+#include <immintrin.h>
+#define TRASH_BUFFER_SIZE (16ULL * 1024 * 1024 * 2) // 2x L3 (~16MB) on the x86 machine we use for measurements
+#define PAGE_SIZE 4096
+#endif
+
+#ifdef __aarch64__
+#include "./headers/kperf.h"
+#include <arm_acle.h>
+#define TRASH_BUFFER_SIZE (1502838784ULL * 2) // 2x SLC (~1.5GB) on M3 Pro
+#define PAGE_SIZE 16384
+#endif
+
+#define N_OBSTACLES 2
+
+// Benchmark parameters (mostly copied from mvm.c in hw1)
+#define WARMUP_ITERS 3
+#define NUM_REPS 15
+#define NUM_RUNS 1
+#define CYCLES_REQUIRED 1e8
+#define MAX_NUM_RUNS (1 << 14)
+
+// Flushes caches by streaming reads through a large persistent buffer.
+long long flush_cache() {
+  static volatile char *trash_buffer = nullptr;
+  static bool initialized = false;
+
+  if (!initialized) {
+    trash_buffer = new volatile char[TRASH_BUFFER_SIZE];
+
+    // Touch one byte per page once so pages are physically mapped. And we avoid paying the cost of page faults during cache trashing below.
+    for (size_t i = 0; i < TRASH_BUFFER_SIZE; i += PAGE_SIZE) {
+      trash_buffer[i] = 1;
+    }
+
+    initialized = true;
+  }
+
+  long long acc = 0;
+
+  for (size_t i = 0; i < TRASH_BUFFER_SIZE; i += CACHE_BLOCK_SIZE) {
+    // Access one byte per cache block is enough to populate the entire block
+    acc += trash_buffer[i];
+  }
+
+#ifdef __x86_64__
+  _mm_lfence();
+#endif
+
+#ifdef __aarch64__
+  __isb(0xF);
+#endif
+
+  asm volatile("" ::: "memory");
+
+  return acc;
+}
+
+int main(int argc, const char *argv[]) {
+  // Check that the correct number of arguments has been passed.
+  //
+  // Expected usage:
+  //
+  //   ./main <number_of_pedestrians> <number_of_iterations> [csv_output_path]
+  //
+  // The optional third argument enables CSV dumping for visualization.
+  if (argc < 3) {
+    printf("Usage: ./main <number_of_pedestrians> <number_of_iterations> [csv_output_path]\n");
+    printf("Each iteration takes %.2f seconds in the simulation.\n", dt);
+    return 1;
+  }
+
+  // Parse command-line arguments.
+  int n_p = atoi(argv[1]);
+  int n_iter = atoi(argv[2]);
+
+  if (n_p <= 0) {
+    printf("Error: <number_of_pedestrians> must be a positive integer, got '%s'\n", argv[1]);
+    return 1;
+  }
+  if (n_iter <= 0) {
+    printf("Error: <number_of_iterations> must be a positive integer, got '%s'\n", argv[2]);
+    return 1;
+  }
+
+  // If provided, dump_path is used to write simulation states to CSV.
+  // In benchmark mode, this path is intentionally ignored to avoid measuring
+  // file I/O overhead.
+  const char *dump_path = (argc >= 4) ? argv[3] : nullptr;
+
+#if BENCHMARK
+
+#if ROOFLINE
+  volatile long long trash_value;
+#endif
+
+#ifdef __aarch64__
+  // Initialize ARM performance counters.
+  kperf_init();
+  struct performance_counters startperf, endperf;
+#endif
+
+  // Warmup runs, to bring caches, predictors, frequency to steady state. These are not measured.
+  // Each run gets a fresh initialized state because run_simulation mutates the
+  // pedestrians and board state.
+  for (int i = 0; i < WARMUP_ITERS; i++) {
+    Pedestrian *P = init_pedestrians(n_p);
+    Board board = init_board_without_obstacles();
+    run_simulation(P, board, n_p, n_iter, nullptr);
+    delete[] P;
+  }
+
+  // Calibration: finds num_runs such that one batch runs for at least
+  // CYCLES_REQUIRED cycles. A long batch keeps makes the timer and other
+  // noise overhead, negligible relative to the kernel execution cost we're
+  // actually trying to measure.
+  //
+  // Skipped when ROOFLINE is enabled: cold-cache measurements need
+  // exactly one timed simulation per batch, otherwise only the first
+  // call starts cold and subsequent calls measure warm-cache behavior.
+  // We can use large enough inputs so a single call already exceeds CYCLES_REQUIRED,
+  // when measuring for roofline plot.
+  // Note: we implemented the calibration exactly as it is done in mvm.c from hw1, we also
+  // used the same values for NUM_RUNS, etc
+  int num_runs = NUM_RUNS;
+#if !ROOFLINE
+  while (num_runs < MAX_NUM_RUNS) {
+    Pedestrian *P = init_pedestrians(n_p);
+    Board board = init_board_without_obstacles();
+
+    long double cycles;
+
+#ifdef __x86_64__
+    myInt64 start = start_tsc();
+#endif
+
+#ifdef __aarch64__
+    startperf = kperf_get_counters();
+#endif
+
+    for (int j = 0; j < num_runs; j++) {
+      run_simulation(P, board, n_p, n_iter, nullptr);
+    }
+
+#ifdef __x86_64__
+    cycles = (long double)stop_tsc(start);
+#endif
+
+#ifdef __aarch64__
+    endperf = kperf_get_counters();
+    cycles = (long double)(endperf.cycles - startperf.cycles);
+#endif
+
+    delete[] P;
+
+    if (cycles >= CYCLES_REQUIRED)
+      break;
+    num_runs *= 2;
+  }
+#endif
+
+  // Store the cycle count of each measured repetition.
+  // The median is then used as the final timing result.
+  std::vector<long double> cycles_v;
+  cycles_v.reserve(NUM_REPS);
+
+  // Measurement phase
+  for (int i = 0; i < NUM_REPS; i++) {
+    Pedestrian *P = init_pedestrians(n_p);
+    Board board = init_board_without_obstacles();
+
+#if ROOFLINE
+    trash_value = flush_cache();
+#endif
+
+#ifdef __x86_64__
+    myInt64 start = start_tsc();
+#endif
+#ifdef __aarch64__
+    startperf = kperf_get_counters();
+#endif
+
+    for (int j = 0; j < num_runs; j++) {
+      // Disable CSV dumping during benchmarking to avoid measuring file I/O
+      // overhead. Initialization is also excluded from the measured region.
+
+      run_simulation(P, board, n_p, n_iter, nullptr);
+    }
+
+#ifdef __x86_64__
+    long double cycles = (long double)stop_tsc(start) / num_runs;
+#endif
+#ifdef __aarch64__
+    endperf = kperf_get_counters();
+    long double cycles = (long double)(endperf.cycles - startperf.cycles) / num_runs;
+#endif
+
+    delete[] P;
+    cycles_v.push_back(cycles);
+  }
+
+  std::sort(cycles_v.begin(), cycles_v.end());
+  // Use the median cycle count to reduce the effect of noisy measurements.
+  long double T = cycles_v[NUM_REPS / 2];
+
+#else
+
+  // Normal execution mode. If dump_path is provided, the simulation writes a CSV
+  // file that can later be used to generate a video of the simulation.
+  Pedestrian *P = init_pedestrians(n_p);
+  Board board = init_board_without_obstacles();
+  run_simulation(P, board, n_p, n_iter, dump_path);
+
+  delete[] P;
+
+#endif
+
+#if BENCHMARK
+
+  // Flop-count per simulation iteration.
+  //
+  // The total work W(n) is estimated from the number of additions,
+  // multiplications, divisions, square roots, and exponentials performed by the
+  // simulation kernels.
+
+  // symmetry: each pedestrian-pedestrian pair is computed once instead of twice,
+  // so the pairwise (n_p - 1) terms get halved -> n_p * (n_p - 1) / 2 pairs total.
+  // the self-driving force, obstacle force and update pass are untouched.
+  long long pairs = (long long)n_p * (n_p - 1) / 2;
+
+  long long add_count_per_iter = n_p * (2 + N_OBSTACLES * 10 + 2) + n_p * 7 + pairs * 14;
+  long long mult_count_per_iter = n_p * (4 + N_OBSTACLES * 13) + n_p * 16 + pairs * 24;
+  long long div_count_per_iter = n_p * (N_OBSTACLES * 1) + n_p * 2 + pairs * 1;
+  long long sqrt_count_per_iter = n_p * (N_OBSTACLES * 1) + n_p * 3 + pairs * 3;
+  long long exp_count_per_iter = n_p * (N_OBSTACLES * 1) + pairs * 1;
+
+  long double W_per_iter = add_count_per_iter * cost_add + mult_count_per_iter * cost_mult + div_count_per_iter * cost_div + sqrt_count_per_iter * cost_sqrt + exp_count_per_iter * cost_exp;
+
+  // Estimated memory traffic per iteration.
+  // TODO: refine this model to account for actual memory accesses, cache reuse,
+  // and the full interaction loop.
+
+  long long Q_per_iter = sizeof(Pedestrian) * n_p + sizeof(Obstacle) * N_OBSTACLES;
+
+  // Operational intensity:
+  //
+  //   I(n) = W(n) / Q(n)
+  //
+  // where W is estimated work in flops and Q is estimated memory traffic in
+  // bytes.
+
+  long double I = W_per_iter / Q_per_iter;
+  long double W = W_per_iter * n_iter;
+
+  // Performance in estimated flops per cycle.
+  long double P = W / T;
+
+  printf("W(n) per iteration: %.2Lf flops\n", W_per_iter);
+  printf("Q(n) per iteration: %lld bytes\n", Q_per_iter);
+  printf("I(n): %.2Lf flops/byte\n", I);
+  printf("W(n): %.2Lf flops\n", W);
+  printf("T(n): %.2Lf cycles\n", T);
+  printf("P(n): %.2Lf flops/cycle\n", P);
+
+#endif
+
+  return 0;
+}