Re: Array and memory usage

[mheaney@on2.com (Matthew Heaney)]

Robert A Duff <bobduff@shell01.TheWorld.com> wrote in message news:<wccfzpuajbg.fsf@shell01.TheWorld.com>...
> 
> I thought it happened automatically.  That is, if I say:
> 
>     X: array (1..100_000_000) of Integer;
> 
> it would allocate 400,000,000 bytes of virtual memory, but only allocate
> physical pages on demand.  I believe that much works on Windows (without
> calling windows-specific stuff like SEH).  (Windows 2000, Windows XP.)
> The problem I found was that it allocated 400,000,000 bytes of backing
> store, which was annoying.
> 
> Am I misinformed?

Windows is going to commit all that memory up front, which (as Randy
pointed out) will indeed allocate backing store.

The solution is to "reserve" that range of virtual memory, without
actually "committing" the pages (to physical memory).  Then use SEH to
"commit" the pages as necessary, when a page fault occurs.