gistfile1.txt

/* When mallocing a huge amount of data, you will be put directly in mmap */
/* however, if you manage to alloc and desalloc blocks of data under 0x80000 */
/* you will be able to change the threshold and have bigger blocks of data */
/* alloced in the brk() heap. */
aris@ubuntu1204-32:$ cat mesures.c 
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main(){
  int i;
	int len = 0x20000 * 4 - 10 * 4096 - 8;
	char *ptr;
	for(i=0;i<20;++i){
		malloc(i*100);
	}
	printf("Mallocing %d bytes\n", len);
	for(i=0;i<3;++i){
		ptr=malloc(len);
		printf("p: %p\n",ptr);
		free(ptr);
	}
	len = 0x20000 * 4 - 8;
	printf("Mallocing %d bytes\n", len);
	for(i=0;i<3;++i){
		ptr=malloc(len);
		printf("p: %p\n",ptr);
		free(ptr);
	}
	len = 0x20000 * 4 + 10;
	printf("Mallocing %d bytes\n", len);
	for(i=0;i<3;++i){
		ptr=malloc(len);
		printf("p: %p\n",ptr);
		free(ptr);
	}
	return 0;
}
/*
aris@ubuntu1204-32:$ ./mesures 
Mallocing 483320 bytes
p: 0xb74c8008
p: 0x8c10ac0
p: 0x8c10ac0
Mallocing 524280 bytes
p: 0x8c10ac0
p: 0x8c10ac0
p: 0x8c10ac0
Mallocing 524298 bytes
p: 0x8c10ac0
p: 0x8c10ac0
p: 0x8c10ac0
*/