From d95035ee637e7d69104e76cfb8515c0bece10160 Mon Sep 17 00:00:00 2001
From: Saveliy Yusufov <sy2685@columbia.edu>
Date: Fri, 9 Feb 2024 11:18:55 -0500
Subject: [PATCH] Fix FFTW benchmark to use wall time

---
 benches/main.c | 27 +++++++++++++++++++++------
 profile.sh     | 10 +++++++++-
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/benches/main.c b/benches/main.c
index ac97c06..f0a2dcc 100644
--- a/benches/main.c
+++ b/benches/main.c
@@ -2,17 +2,29 @@
 #include <math.h>
 #include <fftw3.h>
 #include <time.h>
+#include <stdint.h>	// uint64
+#include <time.h>	// clock_gettime
+
+#define BILLION 1000000000L
+
 
 int main(int argc, char** argv) {
     if (argc != 2) {
         fprintf(stderr, "Usage: %s <n>\n", argv[0]);
         return EXIT_FAILURE;
     }
+
     long n = strtol(argv[1], NULL, 0);
-    printf("%ld\n", n);
 
     int N = 1 << n;
+
+    uint64_t diff1;
+	struct timespec start, end;
+    clock_gettime(CLOCK_MONOTONIC, &start);
     fftw_complex* in = fftw_alloc_complex(N);
+    fftw_plan p = fftw_plan_dft_1d(N, in, in, FFTW_FORWARD, FFTW_ESTIMATE);
+    clock_gettime(CLOCK_MONOTONIC, &end);
+	diff1 = BILLION * (end.tv_sec - start.tv_sec) + end.tv_nsec - start.tv_nsec;
 
     double a = 1.0;
     for (int i = 0; i < N; i++) {
@@ -20,13 +32,16 @@ int main(int argc, char** argv) {
         in[i][1] = ((double)rand()/(double)(RAND_MAX)) * a;
     }
 
-    double tic = clock();
-    fftw_plan p = fftw_plan_dft_1d(N, in, in, FFTW_FORWARD, FFTW_ESTIMATE);
+    uint64_t diff2;
+	struct timespec start1, end1;
+    clock_gettime(CLOCK_MONOTONIC, &start1);
     fftw_execute(p);
-    double toc = clock();
-    double elapsed = ((double)(toc - tic) / CLOCKS_PER_SEC) * 1000000;
+    clock_gettime(CLOCK_MONOTONIC, &end1);	/* mark the end1 time */
+	diff2 = BILLION * (end1.tv_sec - start1.tv_sec) + end1.tv_nsec - start1.tv_nsec;
+
+    uint64_t diff = diff1 + diff2;
+	printf("%llu\n", (long long unsigned int) diff / 1000);
 
-    printf("%f\n", elapsed);
     fftw_free(in);
     fftw_destroy_plan(p);
     fftw_cleanup();
diff --git a/profile.sh b/profile.sh
index e3cc9c0..81f7573 100755
--- a/profile.sh
+++ b/profile.sh
@@ -1,7 +1,15 @@
 #!/usr/bin/env bash
 
+set -Eeuo pipefail
+
+if [[ "$#" -ne 1 ]]
+then
+    echo "Usage: $0 <n>"
+    exit 1
+fi
+
 RUSTFLAGS='-Ctarget-cpu=native' cargo +nightly build --release --examples
 
-sudo perf record --call-graph=dwarf ./target/release/examples/profile && sudo perf script -f -F +pid > processed_result.perf
+sudo perf record --call-graph=dwarf ./target/release/examples/profile $1 && sudo perf script -f -F +pid > processed_result.perf
 
 echo "done! results in process_result.perf"