From:	jlrubin AT NO_MEAT_BYPRODUCTS DOT bway DOT net (Josh Rubin)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Why is malloc allocating every other page?
Date:	Tue, 07 Oct 1997 06:56:05 GMT
Message-ID:	<3439dc3c.165049@news2.bway.net>
NNTP-Posting-Host:	205.198.117.34
Lines:	36
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

The test program below allocates blocks of 4000 bytes,
which should fit easily in a page even with the malloc
overhead.
--> malloc allocates *every other* page! <--
(the same thing happens with smaller blocks, like 3000 bytes)

--------------
#include <stdio.h>
#include <stdlib.h>

int main()
{
  int n;
  void *p;
  for (n=0;n<10;++n) {
    p = malloc(4000);    /* should fit in 1 page, even with overhead
*/
    printf(" %x\n",(int)p);
  }
  return 0;
}
--------------

 52000
 59000
 5b000
 5d000
 5f000
 61000
 63000
 65000
 67000
 69000

Strip the all-caps text from my address before replying by email.
 Josh Rubin

- Raw text -