check used memory

hi.
is possible check how much memory is allocated and how much memory is really used with application in linux?

i want write this info into my application.

i use this:

Code:

---

const static char StatFile[] = "/proc/self/stat";
    QScopedPointer<FILE, FileCloser> stat(::fopen(StatFile, "r"));
    if ( !stat ) {
        qWarning() << __FILE__ << __LINE__ << "Cannot open stat file";
        return -1;
    }
 
    unsigned long vmsize(0), rss(0);
    int r = ::fscanf(stat.data(),
            "%*d%*s%*s%*d%*d%*d%*d%*d%*u%*u" "%*u%*u%*u%*u%*u%*d%*d%*d%*d%*d"
            "%*d%*u%lu%lu", &vmsize, &rss);
    if ( r != 2 ) {
        qWarning() << __FILE__ << __LINE__ << "Cannot read vmsize and resident size";
        return -1;
    }
 
    const static long PageSize = ::sysconf(_SC_PAGESIZE);
 
    return (rss * PageSize) / 1024;

---

but this is only alocated memory because when i delete some object, this info of memory is not change (maybe after long time)