malloc_test.c

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/time.h>

static int64_t get_time_usec() {
	struct timeval time;
	gettimeofday(&time, NULL);
	return (int64_t)time.tv_sec * 1000000 + time.tv_usec;
}

int main(int argc, char **argv) {
	int i, j; int64_t t1, t2, t3, t4;

	for (i = 0; i < 3; i++) {
		int n = 100 << 20; char *p;
		t1 = get_time_usec();
		p = malloc(n);
		t2 = get_time_usec();
		for (j = 0; j < n; j += 0x1000) p[j] = 12;
		t3 = get_time_usec();
		for (j = 0; j < n; j += 0x1000) p[j] = 34;
		t4 = get_time_usec();
		free(p);
		printf("alloc = %.3fms, touch1 = %.3fms, touch2 = %.3fms\n", (t2-t1) * 0.001, (t3-t2) * 0.001, (t4-t3) * 0.001);
	}

	return 0;
}