Question about memory taken by list structur.
Hi,
I need to use a list structure in my program. I don't use STL list but my own (very simple one, I don't need very sophisticated functions):
Code:
class element
{
public:
int i;
element *next;
element()
{
i=0;
next=NULL;
}
};
class _list
{
public:
element *start,
*last;
_list()
{
start=NULL;
last=NULL;
}
int add(int);
};
int _list::add(int i)
{
element *new_;
new_=new element;
new_->i=i;
new_->next=NULL;
if(last==NULL)
{
start=new_;
last=new_;
}
else
{
last->next=new_;
last=new_;
}
return 0;
}
And then I have such short code:
Code:
_list L[1000000];
int main()
{
for(int i = 0; i < 1000000; i++)
L[i].add(i);
return 0;
}
So I have an array of 10^6 lists. And then to each list L[x] I add one element. So the memory taken by that structure should be something like 19 mb (main list class - 2 pointers each 4 bytes, so it's 8 *10^6/1024/1024 = 7.6 Mb; then we have 10^6 elements, each one has a 1 pointer (4b) and integer number (8b) so it's 12*10^6/1024/1024 = 11.4Mb, to if we sum it up to should be ~ 19 Mb). But when I add sleep(1000) before returning the main function and run ps aux I have:
Quote:
$ ps aux
USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND
apacz 3431 22.4 9.8 25780 24716 p0 S+ 10:36PM 0:00.72 ./my_program
25780Kb? 25Mb? How? Can any one explain me that?
Regards,
apacz
