Re: malloc on 64 AMD64

[Kurt Roeckx <Q@ping.be>]

On Thu, Apr 15, 2004 at 11:24:52AM -0700, Sebastian Haase wrote:
> Hi,
> We are planning to by an Athlon64 (or Opteron) system and since I like debian 
> I am posting this "request":
> What output can I expect from this c program:
> <code>
> #include <stdio.h>
> int main()  {  size_t n;  void *p;  double gb;
>   for(gb=10;gb>.3;gb-=.5) {
> 	n= 1024L * 1024L * 1024L * gb; 
> 	p = malloc( n );
> 	printf("%12lu %4.1lfGb %p\n",n,n/1024./1024./1024.,p);
> 	free(p); }  return 0;  }
> </code>
> 
> BTW: I get this on my Pentium 4
> <terminal>
> haase@baboon:~: make test64 && ./test64
> cc     test64.c   -o test64
> test64.c: In function `main':
> test64.c:5: warning: assignment makes pointer from integer without a cast

Note that you have to include stdlib.h to get the proper
prototype of malloc else you'll corrupt the pointer you get back
and get a segmentation fault in free().

I get:
 10737418240 10.000Gb 0x2a958a5010
 10200547328 9.500Gb 0x2a958a5010
  9663676416 9.000Gb 0x2a958a5010
  9126805504 8.500Gb 0x2a958a5010
  8589934592 8.000Gb 0x2a958a5010
  8053063680 7.500Gb 0x2a958a5010
  7516192768 7.000Gb 0x2a958a5010
  6979321856 6.500Gb 0x2a958a5010
  6442450944 6.000Gb 0x2a958a5010
  5905580032 5.500Gb 0x2a958a5010
  5368709120 5.000Gb 0x2a958a5010
  4831838208 4.500Gb 0x2a958a5010
  4294967296 4.000Gb 0x2a958a5010
  3758096384 3.500Gb 0x2a958a5010
  3221225472 3.000Gb 0x2a958a5010
  2684354560 2.500Gb 0x2a958a5010
  2147483648 2.000Gb 0x2a958a5010
  1610612736 1.500Gb 0x2a958a5010
  1073741824 1.000Gb 0x2a958a5010
   536870912 0.500Gb 0x2a958a5010

Note that that pointer is more than 32 bit.


Kurt