benchmark

compile.sh

#!/bin/sh

gcc -c -fpic lib.c
gcc -shared -o libfoo.so lib.o
gcc -L`pwd` -O3 -o test test.c -lfoo
echo "Before calling ./test, please do export LD_LIBRARY_PATH=`pwd`:\$LD_LIBRARY_PATH"

lib.c

#include "lib.h"
void do_something(float i) { /* lol, nothing XD */ }

lib.h

void do_something(float i);

test.c

#include <stdio.h>
#include <time.h>
#include <stdint.h>
#include "lib.h"

int main() {
	clock_t t1, t2, t3, t4, t5, t6;
	clock_t e;
	t1 = clock();
	uint64_t i;
	uint64_t num_it = 1000 * 1000 * 10;
	float inv1000 = 1/1000.0;
	float inv1024 = 1/1024.0;
	float t = 157963;
	for (i = 0; i < num_it; i++) {
		do_something(i * inv1000);
	}
	t2 = clock();
	for (i = 0; i < num_it; i++) {
		do_something(i / 1000.0);
	}
	t3 = clock();
	for (i = 0; i < num_it; i++) {
		do_something(i * inv1024);
	}
	t4 = clock();
	for (i = 0; i < num_it; i++) {
		do_something(i / 1024.0);
	}
	t5 = clock();
	for (i = 0; i < num_it; i++) {
		do_something(i);
	}
	t6 = clock();
	e = t6 - t5;
	printf("Not accounting for overhead: %f\n", (float)e / CLOCKS_PER_SEC);
	printf("%f %f %f %f\n",
		(float)(t2 - t1 - e) / CLOCKS_PER_SEC, (float)(t3 - t2 - e) / CLOCKS_PER_SEC,
		(float)(t4 - t3 - e) / CLOCKS_PER_SEC, (float)(t5 - t4 - e) / CLOCKS_PER_SEC);
	return 0;
}