How to return GC-d memory back to OS

[Serg Kovrov]

* Oskar Linde:
> For a long time, even linux malloc()/free() would not return memory to 
> the OS. Usually, memory is allocated from the OS using brk() or similar 
> system calls and an application can only return memory from the end of 
> the virtual address range the application has been allocated. In 
> general, this requires a relocating/compacting GC, as even a single 
> allocated byte at the top end of your virtual address space will prevent 
> the OS from shrinking it.
> 
> But apart from needing much swap space, there are no draw backs of using 
> much virtual memory. The memory you don't use (but exists in your 
> virtual address range) will not map to physical memory and will not 
> affect your computers performance.
> 
> /Oskar

I'm not sure, Oskar, as I am not an expert in that matter...

But... I'm not tried on linux but on Windows (my target OS is 2000/XP 
family so far) 'delete' do exactly what I want.

For example, in C++ (GCC/mingw) I could allocate with 'new' 50Mb, and 
see in task manager or performance monitor that my "private bytes" are 
increased about that size. When I 'delete' it, I see that "private 
bytes" count is dropped to the same level it was before. Nice.

As I understand "private bytes" are amount of memory my process uses 
exclusively and can not be used by anyone else. And that I define for 
myself as memory footprint - correct me if I wrong.

Same example in D show that GC greedily hold everything it get from OS. 
  And that is definitely what I do not want.