"nos1eep" <notme@420,com> wrote:
>An MVP strikes again. How 'bout looking in Task Manager\Performance. It
>tells you the pf usage and the pf usage history.
>
>-nos1eep
>
You have to know the definitions behind the reported values.
Task Manager includes the unused portions of memory allocation
requests (which are always mapped to locations in the page file) in
its reported value for pf usage.
For example on this computer at the present moment, with 768 mb of
RAM, Task Manager reports PF Usage of 264 mb. The page file usage
monitor, on the other hand, reports 30 mb.
This means that I have 30 mb of active RAM content that has been moved
to the page file (that is the relevant consideration in terms of
assessing the potential benefit of addding more RAM) and 234 mb (264
minus 30) of RAM has been requested but never actually used.
Memory allocation requests are issued by application programs, device
drivers, and windows components; and they all invariably ask for
larger allocations than they actually use under normal circumstances.
So Windows, by design, allocates locations in RAM only to those
portions that are actually used, and allocates locations in the page
file to the unused portions. Note that this mapping of the unused
portions to the page file does not require any actual disk activity,
just entries in the memory mapping tables maintained by the CPU.
And if for some reason a previously requested but unused portion of a
RAM allocation should now be required then the memory manage will
instantaneously remap that portion to available locations in RAM. It
may be necessary to move some other RAM content that is idle out to
the page file in order to free up the required RAM.
This mapping of unused allocation requests to the page file is one
very good reason why people should never disable the page file in
Windows XP, even if they have a vast amount of RAM.
Hope this clarifies the situation.
Good luck
Ron Martell Duncan B.C. Canada
--
Microsoft MVP
On-Line Help Computer Service
http://onlinehelp.bc.ca
In memory of a dear friend Alex Nichol MVP
http://aumha.org/alex.htm