free() does not call sbrk()
Martin Walter
martin.walter@gmail.com
Tue Sep 15 21:06:00 GMT 2009
> ...
> For a discussion on the design see: http://g.oswego.edu/dl/html/malloc.html
> which is referenced in libc/stdlib/mallocr.c
Thanks for clarification!
> My simple test of mallocing a block of 4000 and freeing it back again in an
> infinite loop results in the same pointer being given back each time and no
> increment in memory usage. I do not know why you are not seeing similar
> behavior for your test. Is there something else in your loop other than
> malloc/free? (mine has a printf as well)
Actually no. Please take a look at my code:
#include "UART.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static void alloc (int size)
{
char buf[128];
int len;
char *ptr = malloc (size);
if (ptr != NULL)
{
len = sprintf (buf, "ptr: %d\r\n", (int)ptr);
UART_write(0, buf, len);
free (ptr);
}
}
int main (int argc, char *argv[])
{
register int i;
for (i = 0; i < 10; ++i)
alloc (4000);
return 0;
}
And the output:
ptr: 2016
ptr: 6024
ptr: 10032
ptr: 14040
ptr: 18048
ptr: 22056
ptr: 26064
ptr: 30072
ptr: 34080
ptr: 38088
Kind regards,
Martin
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