The XP Memory Manager does not use "unused(free) physical memory"

[Guest]

The XP Memory Manager does not use "unused(free) physical memory" before
using the page file on the hard drive. Is there a registry setting I can use
that will modify that?

 

[Carey Frisch [MVP]]

RAM, Virtual Memory, Pagefile and all that stuff
http://support.microsoft.com/kb/555223/en-us

 

[Glen]

You probably misunderstand how windows uses the page file.

 

[Ron Martell]

The XP Memory Manager does not use "unused(free) physical memory" before
using the page file on the hard drive. Is there a registry setting I can use
that will modify that?

Are you certain that Windows is actually *using* the page file, that
is actually moving active memory content from RAM to the page file?

Much of what is reported as "PF Usage" by Windows Task Manager is
actually phantom usage - there is nothing actually written to the page
file. What Windows is doing is using address space from the page file
for the *unused* portions of memory allocation requests.

Almost everything - Windows components, device drivers, application
programs - asks for memory allocations requests that are larger than
what is usually required under normal circumstances. By design,
Windows must provide memory address locations to satisfy all of these
allocation requests. What it does is to allocate RAM only to those
portions of the requests that are actually used, and uses locations in
the page file for the unused portions. Note that this mapping of
unused portions of memory requests to the page file does not require
any actual disk activity, all that is needed are entries in the memory
mapping tables maintained by the CPU.

If subsequent events result in a requirement to use some of the unused
portions of previously allocations then these portions will be
remapped at that time from the page file to available locations in
RAM.

Hope this explains the situation.

Good luck

Ron Martell Duncan B.C. Canada
--
Microsoft MVP (1997 - 2006)
On-Line Help Computer Service
http://onlinehelp.bc.ca

"Anyone who thinks that they are too small to make a difference
has never been in bed with a mosquito."

 

[frodo]

The XP Memory Manager does not use "unused(free) physical memory" before
using the page file on the hard drive.

I believe this is a misunderstanding; XP will always use as much real RAM
as possible, it never leaves (much) actually "unused". Note that
"available" RAM is not the same as "unused" RAM.

You may be confused by a featue in the windows programing model where an
application can ask for a large chunk of RAM that is "mapped" to the page
file. This is a common technique for pre-allocating a large amount of
temp RAM without "tieing up" real RAM until its actually needed.