64 bit memory usage

[Ian Kelly]

On 12/8/2010 11:42 PM, Dennis Lee Bieber wrote:
> 	The page file can be larger than physical memory because it contains
> memory "images" for multiple processes. However, all those "images" have
> to map into the physically addressable memory -- so a process is likely
> limited to physical memory, but you can have multiple processes adding
> up to physical + pagefile in total.

Only those pages that are currently paged in need be mapped to physical 
memory.  The rest are not mapped to anything at all (other than a 
location in the page file) -- once a page is paged out, it need not be 
put back in its original page frame when it is paged in again.

Since a process need not have all its pages in physical memory 
simultaneously, there is no reason to suppose that a single process 
could not consume the entirety of the available virtual memory (minus 
what is used by the operating system) on a 64-bit system (the same 
cannot be said of a 32-bit system, where the total virtual memory 
available may well be larger than the addressable space).