Re: max heap usage of a Linux process

["Christ, Bryan" <bryan.christ@hp.com>]

If you want to know how much you are using, look at uordblks not
ordblks.  The allocator dishes out memory in chunks (not the same has
bytes requested via malloc() so there will most often be some
difference).  

See the GNU documentation at:
http://www.gnu.org/software/libc/manual/html_node/Statistics-of-Malloc.html#Statistics-of-Malloc

BTW, I think the chunk size will always be a multiple of page size (see
the man pages for getpagesize() -- but I haven't give it any thorough
investigation).  Perhaps someone on this list can confirm.

On Mon, 2006-11-13 at 16:59 +0100, Markus Rechberger wrote:
> Hi,
> 
> On 11/13/06, Dan Gary <funkychunkymunky@gmail.com> wrote:
> > unless parent is asking about malloc'd space, then mallinfo() or
> > malloc_stats() might be what they're looking for, memory profiling the
> > manual way, gotta love it
> >
> 
> interesting didn't know that..
> 
> though now I have a question about it ..
> 
> #include <malloc.h>
> #include <stdio.h>
> #include <stdlib.h>
> 
> int main(){
>         char *foo;
>         printf("total free space: %d\n",mallinfo().fordblks);
>         foo=malloc(500000);
>         if(foo){
>                 printf("successfully allocated!\n");
>         } else {
>                 printf("error allocating!\n");
>         }
>         printf("arena: %d\n",mallinfo().arena);
>         printf("ordblks: %d\n",mallinfo().ordblks);
>         printf("max total allocated space: %d\n",mallinfo().usmblks);
>         printf("total allocated space: %d\n",mallinfo().uordblks);
>         printf("total free space: %d\n",mallinfo().fordblks);
> 
>         return 0;
> }
> 
> outputs:
> total free space: 0
> successfully allocated!
> arena: 0
> ordblks: 1
> max total allocated space: 0
> total allocated space: 0
> total free space: 0
> 
> If I allocate 50000bytes then it outputs:
> total free space: 0
> successfully allocated!
> arena: 184320
> ordblks: 1
> max total allocated space: 0
> total allocated space: 50008
> total free space: 134312
> 
> does anyone have an explanation for that?
> 
> Markus
> -
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