Total addressable by XP....RAM+Page file=4 gigs?

[kroger]

Hi, I have one gig of hard RAM and set my page file to 4 gigs, in two
2-gig partitions, one on each of two hard drives.

I know windows XP (32 bit version) can only address 4 gigs of hard RAM.
Is that also true for memory in general such that the total of hard RAM
+ page file that the system can see is 4 gigs total? So it can only see
three gigs of my four gigs of page file?

Thanks much!

Jim

 

[DL]

Haveing posted a similar Q a few days ago, and following the replies, is
there some specific reason why you still think 4gb of page file split across
two drives is going to help?
Just wondered

 

[Mike Hall - MS MVP Windows Shell/User]

Kroger

Set your pagefile to 'Windows managed'.. you do not need a 4gb pagefile..

Anything you have seen re. Windows and 4gb relates to installed physical
memory.. 32bit XP running on 32bit hardware does not show a full 4gb RAM,
although the system does utilise 4gb..

 

[kroger]

Thanks Mike. Can I just make sure I'm clear?

WinXP can only see/use 4 gigs of hard ram, but can address more
than 4 gigs when the total of RAM plus Page File is greater than
4 gigs?

I thought memory addressing was limited by the size of number
you can fit into the size of the computer's word, so that 32 bit
address spaces can only address 2^32 addresses, which
is equal to 4,294,967,296 bytes, or 4 gigs of RAM. I hope
this is wrong. One way I can be wrong is that in 32 bit
addressing the byte may be different on different architectures.

Thanks,
Jim

 

[kroger]

Yes, because the Help in Windows XP specifically says so, and becasue
I understand that XP can access the two independently, and thus often,
in parallel.

Now I am asking about addressing space under XP.

Thanks,
Jim

 

[Richard Urban]

Don't even worry about your pagefile. Set it to system managed on each
drive.

The only way you are ever going to use 4 gig of page file is by running a
computer with 64 meg of physical RAM and then opening about 20 Photoshop
projects and editing them simultaneously. (-:

--
Regards,

Richard Urban
Microsoft MVP Windows Shell/User
(For email, remove the obvious from my address)

Quote from George Ankner:
If you knew as much as you think you know,
You would realize that you don't know what you thought you knew!

 

[Mike Hall - MS MVP Windows Shell/User]

Kroger

XP can utilize 4gb RAM, but when run 32bit on a 32bit system will not show
all of the RAM, but it is still used.. 64bit XP will all of the RAM..

Your system has 1gb fitted.. set the pagefile to 'Windows managed' and
forget about it.. in general use, your system will not peak much above a
400mb pagefile, if that even..

 

[Tim Slattery]

Thanks Mike. Can I just make sure I'm clear?

WinXP can only see/use 4 gigs of hard ram, but can address more
than 4 gigs when the total of RAM plus Page File is greater than
4 gigs?

I thought memory addressing was limited by the size of number
you can fit into the size of the computer's word, so that 32 bit
address spaces can only address 2^32 addresses, which
is equal to 4,294,967,296 bytes, or 4 gigs of RAM. I hope
this is wrong. One way I can be wrong is that in 32 bit
addressing the byte may be different on different architectures.

Each process running in WinXP has its own 4GB virtual memory space.
That's realized by the OS using whatever physical memory is installed,
as well as the swap file on disk. Less recently used parts of memory
are written to the swap file to make room for stuff that needs to be
in RAM to be accessed NOW,.

Another point: XP has a physical address space of 4GB. But if you
install 4GB of RAM (assuming your motherboard will support that much),
XP won't be able to see all of it. This document:
http://download.microsoft.com/download/e/b/a/eba1050f-a31d-436b-9281-92cdfeae4b45/mem-mgmt.doc

discusses RAM usage in XP and other MS operating systems. The fourth
paragraph on page 10 says this:

<QUOTE>
The physical address space is used to address more than just RAM. It
is also used to address all of the memory and some of the registers
presented by devices. Consequently, if a machine is configured with
the maximum amount of physical memory, some of that memory will be
unusable because some of the physical address space is mapped for
other uses.
</QUOTE>

 

[kroger]

Thanks Mike, Tim, Richard.....

This has been very helpful. I run Suse Linux on several 64 bit
machines, to use matlab to crunch data. The data files are typically 3
- 4 gigs and matlab sometimes demands up to 13 gigs to open and
translate a data file. We have 6 gigs of hard ram and set the swap to
12 gigs. Using the "free" command we can watch ram fill then swap get
filled as we work.

I want to use winXP to process some data at home (smaller parts than
above, of course), and assumed that things would work in a similar
way...set the page file to be huge to augment my 1 gig of hard ram, and
let things run overnight, using the page file. I know most
recommendations are to let the page file be equal to hard ram, just as
in the linux world, but clearly we would not be able to work in the lab
if we followed that.

I"ll look into windows managed page files. I made partitions for the
page file, and it seemed harmless to just let the page file fill the
partitions.

Thanks much,
Jim

 

[Ron Martell]

Thanks Mike, Tim, Richard.....

This has been very helpful. I run Suse Linux on several 64 bit
machines, to use matlab to crunch data. The data files are typically 3
- 4 gigs and matlab sometimes demands up to 13 gigs to open and
translate a data file. We have 6 gigs of hard ram and set the swap to
12 gigs. Using the "free" command we can watch ram fill then swap get
filled as we work.

I want to use winXP to process some data at home (smaller parts than
above, of course), and assumed that things would work in a similar
way...set the page file to be huge to augment my 1 gig of hard ram, and
let things run overnight, using the page file. I know most
recommendations are to let the page file be equal to hard ram, just as
in the linux world, but clearly we would not be able to work in the lab
if we followed that.

I"ll look into windows managed page files. I made partitions for the
page file, and it seemed harmless to just let the page file fill the
partitions.

Thanks much,
Jim

Do not make the mistake of applying Linux principles and rules to
Windows XP page file (or anything else). That is as bad as trying to
apply auto mechanics technigues to heart surgery (or vice versa).

Your idea of using two page file on two different physical drives is a
good one, as Windows XP will use whichever page file is optimal for
each paging operation.

For more information about memory management and page files in Windows
XP see the article by the late Alex Nichol MVP at
http://aumha.org/win5/a/xpvm.htm

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."