Change FFT benchmark to use static allocated temporary arrays.

app/benchmark_fft/main.cpp

 #include "pls/internal/scheduling/scheduler.h"
 #include "pls/internal/scheduling/static_scheduler_memory.h"
-#include "pls/internal/helpers/profiler.h"
 
 using namespace pls::internal::scheduling;
 
-#include <iostream>
-#include <complex>
-#include <vector>
-
 #include "benchmark_runner.h"
 #include "benchmark_base/fft.h"
 
 using namespace comparison_benchmarks::base;
 
-void conquer(fft::complex_vector::iterator data, int n) {
+void pls_conquer(fft::complex_vector::iterator data, fft::complex_vector::iterator swap_array, int n) {
   if (n < 2) {
     return;
   }
 
-  fft::divide(data, n);
+  fft::divide(data, swap_array, n);
   if (n <= fft::RECURSIVE_CUTOFF) {
-    fft::conquer(data, n / 2);
-    fft::conquer(data + n / 2, n / 2);
+    fft::conquer(data, swap_array, n / 2);
+    fft::conquer(data + n / 2, swap_array + n / 2, n / 2);
   } else {
-    scheduler::spawn([data, n]() {
-      conquer(data, n / 2);
+    scheduler::spawn([data, n, swap_array]() {
+      pls_conquer(data, swap_array, n / 2);
     });
-    scheduler::spawn([data, n]() {
-      conquer(data + n / 2, n / 2);
+    scheduler::spawn([data, n, swap_array]() {
+      pls_conquer(data + n / 2, swap_array + n / 2, n / 2);
     });
     scheduler::sync();
   }
@@ -37,11 +32,7 @@ void conquer(fft::complex_vector::iterator data, int n) {
 
 constexpr int MAX_NUM_THREADS = 8;
 constexpr int MAX_NUM_TASKS = 32;
-constexpr int MAX_STACK_SIZE = 1024 * 32;
-
-static_scheduler_memory<MAX_NUM_THREADS,
-                        MAX_NUM_TASKS,
-                        MAX_STACK_SIZE> global_scheduler_memory;
+constexpr int MAX_STACK_SIZE = 1024 * 8;
 
 int main(int argc, char **argv) {
   int num_threads;
@@ -53,12 +44,16 @@ int main(int argc, char **argv) {
   benchmark_runner runner{full_directory, test_name};
 
   fft::complex_vector data = fft::generate_input();
+  fft::complex_vector swap_array(data.size());
 
+  static_scheduler_memory<MAX_NUM_THREADS,
+                          MAX_NUM_TASKS,
+                          MAX_STACK_SIZE> global_scheduler_memory;
   scheduler scheduler{global_scheduler_memory, (unsigned) num_threads};
 
   runner.run_iterations(fft::NUM_ITERATIONS, [&]() {
     scheduler.perform_work([&]() {
-      conquer(data.begin(), fft::SIZE);;
+      pls_conquer(data.begin(), swap_array.begin(), fft::SIZE);;
     });
   }, fft::NUM_WARMUP_ITERATIONS);
   runner.commit_results(true);

extern/benchmark_base/include/benchmark_base/fft.h

@@ -18,8 +18,8 @@ typedef std::vector<std::complex<double>> complex_vector;
 
 complex_vector generate_input();
 
-void divide(complex_vector::iterator data, int n);
-void conquer(complex_vector::iterator data, int n);
+void divide(complex_vector::iterator data, complex_vector::iterator swap_array, int n);
+void conquer(complex_vector::iterator data, complex_vector::iterator swap_array, int n);
 void combine(complex_vector::iterator data, int n);
 
 }

extern/benchmark_base/src/fft.cpp

@@ -19,8 +19,7 @@ complex_vector generate_input() {
   return data;
 }
 
-void divide(complex_vector::iterator data, int n) {
-  complex_vector tmp_odd_elements(n / 2);
+void divide(complex_vector::iterator data, complex_vector::iterator tmp_odd_elements, int n) {
   for (int i = 0; i < n / 2; i++) {
     tmp_odd_elements[i] = data[i * 2 + 1];
   }
@@ -47,14 +46,14 @@ void combine(complex_vector::iterator data, int n) {
   }
 }
 
-void conquer(complex_vector::iterator data, int n) {
+void conquer(complex_vector::iterator data, complex_vector::iterator swap_array, int n) {
   if (n < 2) {
     return;
   }
 
-  divide(data, n);
-  conquer(data, n / 2);
-  conquer(data + n / 2, n / 2);
+  divide(data, swap_array, n);
+  conquer(data, swap_array, n / 2);
+  conquer(data + n / 2, swap_array + n / 2, n / 2);
   combine(data, n);
 }