sbrk() on Linux

sbrk() on Linux

[Qingshan Bie]

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Hi,

I got a problem on reporting mem usage on linux. We use sbrk
to report mem usage on SUN and HP. It works well. But it doesn't give
correct data on linux. The problem is if I allocate a memory > 133000
bytes, the sbrk() doesn't work as expected. Can someone help?

attached is my test code

Thanks,

Qingshan

[-- Attachment #2: testsbrk.c --]
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#include <unistd.h>
#include <iostream.h>

double sysMemory(void)
{
  static char *offs = NULL;
  char *th = (char*)sbrk(0);

  if (offs != NULL)
    return (double) ((unsigned int) (th - offs));

  offs = th;

  return 0.0;
}


int main()
{
  double memUsage = sysMemory();
  char * pChar = new char[131000];
  memUsage = sysMemory();
  cout << "mem usage is " << memUsage << endl;
  delete [] pChar;
  return 0;
}

Re: sbrk() on Linux

[Qingshan Bie]

Could anyone help me on this?

Thanks

Qingshan

Qingshan Bie wrote:
> 
> Hi,
> 
> I got a problem on reporting mem usage on linux. We use sbrk
> to report mem usage on SUN and HP. It works well. But it doesn't give
> correct data on linux. The problem is if I allocate a memory > 133000
> bytes, the sbrk() doesn't work as expected. Can someone help?
> 
> attached is my test code
> 
> Thanks,
> 
> Qingshan
> 
>   ------------------------------------------------------------------------
> #include <unistd.h>
> #include <iostream.h>
> 
> double sysMemory(void)
> {
>   static char *offs = NULL;
>   char *th = (char*)sbrk(0);
> 
>   if (offs != NULL)
>     return (double) ((unsigned int) (th - offs));
> 
>   offs = th;
> 
>   return 0.0;
> }
> 
> int main()
> {
>   double memUsage = sysMemory();
>   char * pChar = new char[131000];
>   memUsage = sysMemory();
>   cout << "mem usage is " << memUsage << endl;
>   delete [] pChar;
>   return 0;
> }

-- 
----------------------------------------------------------
Qingshan Bie
Avant! Corporation
46871 Bayside Parkway   Phone: (510) 413-7267 (work)
Fremont, CA 94538       Email: Qingshan_Bie@avanticorp.com