From 2f19e94b0ce78d6ccc9eedbf04b8a3460fd05565 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Mon, 29 Apr 2024 21:59:51 +0200
Subject: Sort benchmarks

---
 sort-benchmark/integers/Makefile          | 20 ++++++++++++++++++++
 sort-benchmark/integers/notes.txt         | 11 +++++++++++
 sort-benchmark/integers/sort.c            | 29 +++++++++++++++++++++++++++++
 sort-benchmark/integers/sort.cpp          | 25 +++++++++++++++++++++++++
 sort-benchmark/integers/sort_parallel.cpp | 28 ++++++++++++++++++++++++++++
 5 files changed, 113 insertions(+)
 create mode 100644 sort-benchmark/integers/Makefile
 create mode 100644 sort-benchmark/integers/notes.txt
 create mode 100644 sort-benchmark/integers/sort.c
 create mode 100644 sort-benchmark/integers/sort.cpp
 create mode 100644 sort-benchmark/integers/sort_parallel.cpp

(limited to 'sort-benchmark/integers')

diff --git a/sort-benchmark/integers/Makefile b/sort-benchmark/integers/Makefile
new file mode 100644
index 0000000..56a37ee
--- /dev/null
+++ b/sort-benchmark/integers/Makefile
@@ -0,0 +1,20 @@
+CC = gcc
+CPP = g++
+OPT = -O3
+VAR = -DARRAYSIZE=100000000
+
+all: sort_c sort_cpp sort_parallel_cpp
+
+sort_c:
+	${CC} ${OPT} ${VAR} -std=c11 -o sort sort.c
+	./sort
+
+sort_cpp:
+	${CPP} ${OPT} ${VAR} -std=c++20 -o sort sort.cpp 
+	./sort
+
+sort_parallel_cpp:
+	${CPP} ${OPT} ${VAR} -std=c++20 -o sort sort_parallel.cpp -ltbb
+	./sort
+
+.PHONY: sort_c sort_cpp sort_parallel_cpp
diff --git a/sort-benchmark/integers/notes.txt b/sort-benchmark/integers/notes.txt
new file mode 100644
index 0000000..7984803
--- /dev/null
+++ b/sort-benchmark/integers/notes.txt
@@ -0,0 +1,11 @@
+- Getting the parallel version to work was a pain. Two major gotchas:
+	(1) -ltbb had to be added *at the end* of the command line
+	(2) clang requires a libstdc++ option to make this work
+  of course everything was terrible to decipher with C++ compile errors
+  being the mess they are.
+- For measuring time I could also use
+	clock_t begin = clock();
+	...
+	clock_t end = clock();
+	double time = (dobule)(end - begin) / CLOCKS_PER_SEC;
+  but it does not work with the parallel version (it meausres CPU clocks).
diff --git a/sort-benchmark/integers/sort.c b/sort-benchmark/integers/sort.c
new file mode 100644
index 0000000..2a23d9d
--- /dev/null
+++ b/sort-benchmark/integers/sort.c
@@ -0,0 +1,29 @@
+#define _POSIX_C_SOURCE 200809L /* Required to use clock_gettime */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+int a[ARRAYSIZE];
+
+int compar(const void *x, const void *y) { return *(int *)x - *(int *)y; }
+
+int main() {
+	srand(time(NULL));
+	for (int i = 0; i < ARRAYSIZE; i++) a[i] = rand() % 1000000000;
+
+	struct timespec begin;
+	clock_gettime(CLOCK_MONOTONIC, &begin);
+
+	qsort(a, ARRAYSIZE, sizeof(int), compar);
+
+	struct timespec end;
+	clock_gettime(CLOCK_MONOTONIC, &end);
+	double time = end.tv_sec - begin.tv_sec +
+		(end.tv_nsec - begin.tv_nsec) / 1000000000.0;
+
+	printf("(%d) C time for %d numbers: %lfs\n",
+		a[ARRAYSIZE/2], ARRAYSIZE, time);
+
+	return 0;
+}
diff --git a/sort-benchmark/integers/sort.cpp b/sort-benchmark/integers/sort.cpp
new file mode 100644
index 0000000..3434d7f
--- /dev/null
+++ b/sort-benchmark/integers/sort.cpp
@@ -0,0 +1,25 @@
+#include <algorithm>
+#include <cstdlib>
+#include <ctime>
+#include <iostream>
+
+int a[ARRAYSIZE];
+
+int main(void) {
+	srand(time(NULL));
+	for (auto &x : a) x = rand() % 1000000000;
+
+	struct timespec begin;
+	clock_gettime(CLOCK_MONOTONIC, &begin);
+
+	std::sort(a, a+ARRAYSIZE,
+		[](const int &x, const int &y) { return x < y; });
+
+	struct timespec end;
+	clock_gettime(CLOCK_MONOTONIC, &end);
+	double time = end.tv_sec - begin.tv_sec +
+		(end.tv_nsec - begin.tv_nsec) / 1000000000.0;
+
+	std::cout << "(" << a[ARRAYSIZE/2] << ") C++ time for " << ARRAYSIZE
+		<< " numbers: " << time << "s\n";
+}
diff --git a/sort-benchmark/integers/sort_parallel.cpp b/sort-benchmark/integers/sort_parallel.cpp
new file mode 100644
index 0000000..5de4158
--- /dev/null
+++ b/sort-benchmark/integers/sort_parallel.cpp
@@ -0,0 +1,28 @@
+/* Requires Thread Building Blocks (libtbb-dev on Debian) */
+
+#include <algorithm>
+#include <cstdlib>
+#include <ctime>
+#include <execution>
+#include <iostream>
+
+int a[ARRAYSIZE];
+
+int main(void) {
+	srand(time(NULL));
+	for (auto &x : a) x = rand() % 1000000000;
+
+	struct timespec begin;
+	clock_gettime(CLOCK_MONOTONIC, &begin);
+
+	std::sort(std::execution::par, a, a+ARRAYSIZE,
+		[](const int &x, const int &y) { return x < y; });
+
+	struct timespec end;
+	clock_gettime(CLOCK_MONOTONIC, &end);
+	double time = end.tv_sec - begin.tv_sec +
+		(end.tv_nsec - begin.tv_nsec) / 1000000000.0;
+
+	std::cout << "(" << a[ARRAYSIZE/2] << ") C++ time for " << ARRAYSIZE
+		<< " numbers (parallel): " << time << "s\n";
+}
-- 
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