RAM and Virtual Memory

[Shane Steinmetz]

I have a question about the use of RAM by Windows XP, Home Edition.

I have 256 MB of RAM. Well, I notice that Windows always insists on
using a pagefile, even if RAM is available -- however small. I thought that
virtual RAM was only used when all physical RAM was consumed. Why is
Windows choosing to use a pagefile even when there's physical RAM available?

Also, I would like some advice.

I'm using an old computer. It's an HP Pavilion 8700, which was handed
down to me by my father. There's some hardware changes, and I've installed
a non-OEM version of Windows XP, Home Edition on it. The maximum amount of
RAM my computer can take is 512 MB. (It can take SDRAM, PC100.) I have 256
MB right now. I am somewhat demanding of this computer. I use it for the
Internet and often run multiple programs at the same time, and sometimes
play some demanding games. Do you think that upgrading to 512 MB will show
noticeable performance improvements, within my operating system and within
the programs I run?

I appreciate any responses.

Shane Steinmetz

 

[Carey Frisch [MVP]]

Virtual Memory in Windows XP
http://aumha.org/win5/a/xpvm.php

--
Carey Frisch
Microsoft MVP
Windows XP - Shell/User

Be Smart! Protect your PC!
http://www.microsoft.com/security/protect/

---------------------------------------------------------------------------------------------------------------------


| I have a question about the use of RAM by Windows XP, Home Edition.
|
| I have 256 MB of RAM. Well, I notice that Windows always insists on
| using a pagefile, even if RAM is available -- however small. I thought that
| virtual RAM was only used when all physical RAM was consumed. Why is
| Windows choosing to use a pagefile even when there's physical RAM available?
|
| Also, I would like some advice.
|
| I'm using an old computer. It's an HP Pavilion 8700, which was handed
| down to me by my father. There's some hardware changes, and I've installed
| a non-OEM version of Windows XP, Home Edition on it. The maximum amount of
| RAM my computer can take is 512 MB. (It can take SDRAM, PC100.) I have 256
| MB right now. I am somewhat demanding of this computer. I use it for the
| Internet and often run multiple programs at the same time, and sometimes
| play some demanding games. Do you think that upgrading to 512 MB will show
| noticeable performance improvements, within my operating system and within
| the programs I run?
|
| I appreciate any responses.
|
| Shane Steinmetz
|
|

 

[Shane Steinmetz]

Thank you for the reference. It seems to have broadened my insight on the
subject of virtual RAM a bit.

So, I guess virtual RAM is a necessity.

Alright, then. Does anyone have any advice for my current memory
situation, which I discussed in my first post?

Shane Steinmetz

 

[Jim]

The referenced article is WRONG ( http://aumha.org/win5/a/xpvm.php ) in one
respect, you do NOT need a paging file *if* you have sufficient RAM, period.
It's just plain wrong in this one respect, and should be rewritten. The
continued reporting that the paging file is necessary is bogus. NOT if you
have sufficient RAM! The virtually memory subsystem is always *there* since
it's an integral part of the OS, but it's implementation in the form of the
paging file (pagefile.sys normally) may or may not be necessary. It all
just depends on whether you have enough RAM to make it irrelevant, and thus,
the paging file *can*, under those circumstances, be deleted.

More comments below...

I have a question about the use of RAM by Windows XP, Home Edition.

I have 256 MB of RAM. Well, I notice that Windows always insists on
using a pagefile, even if RAM is available -- however small. I thought that
virtual RAM was only used when all physical RAM was consumed. Why is
Windows choosing to use a pagefile even when there's physical RAM available?

Not exactly correct, it's more a case of Windows always using the VM
(virtual memory) subsystem, rather than the file itself.

I have 1GB of RAM and have disabled the paging file completely! And yet,
Task Manager shows that at least part of the kernal remains "paged".
Physically, that's impossible, since pagefile.sys doesn't even exist under
C:\ anymore. That leads me to believe that the way virtual memory usage is
being calculated is NOT strictly on consumption of the physical paging file,
but some other factor, something more abstract in the VM. I can't be more
specific because I don't know exactly what that is, but it has to be
something else, perhaps memory management reporting the difference between
*real* vs *potential/delayed* allocations, and throwing the latter into the
VM (paging file) bucket. Something akin to how applications are loaded,
i.e., only piece-meal as they are needed.

Also, I would like some advice.

I'm using an old computer. It's an HP Pavilion 8700, which was handed
down to me by my father. There's some hardware changes, and I've installed
a non-OEM version of Windows XP, Home Edition on it. The maximum amount of
RAM my computer can take is 512 MB. (It can take SDRAM, PC100.) I have 256
MB right now. I am somewhat demanding of this computer. I use it for the
Internet and often run multiple programs at the same time, and sometimes
play some demanding games. Do you think that upgrading to 512 MB will show
noticeable performance improvements, within my operating system and within
the programs I run?

More memory only matters and is useful if you can actually use it. 256MB
is, frankly, only adequate for XP, I believe 512MB is ideal for the average
user. If you want to virtually guarantee that the paging file is NOT needed
and can in fact be disabled, you probably need to reach the 1GB level at a
minimum, obviously beyond your current capabilities.

You can easily exceed the 256MB mark w/ a few apps running concurrently, or
w/ audio/video editing apps, for example. Once you do, you hit the paging
file, and performance deteriorates rapidily. For most, the pain of
*waiting* for IO swapping to complete becomes intolerable.

So monitor your usage, if you rarely if ever come close to 256MB in usage,
more memory buys you nothing. If you do (and it's highly likely you will),
more memory is one of the best investments you can make. There's simply no
comparison in performance between a system that's constantly paging vs. one
that is not.

HTH

Jim

 

[Richard Urban]

Try running PhotoShop (extreme changes and mods to the photo) or AutoCad (a
25 layer - 52 meg drawing, that has to be redrawn due to changes) without a
pagefile!

--
Regards:

Richard Urban

aka Crusty (-: Old B@stard

 

[Jim]

Read my post carefully, if you have *sufficient* RAM, you do NOT need a
paging file! Period!

If you're running Photoshop and it *needs* more RAM than you have currently
have installed, then by definition, you do NOT have *sufficient* RAM. I
choose my words VERY carefully. For many people who do NOT do memory
intensive applications like audio/video/photo editing, they never exceed the
available RAM. If they don't, they do not need the paging file!!!

The document is plain WRONG. I have no such use for memory intensive
applications, I have 1GB of RAM, and never exceed more than 570MB under the
worst of conditions. I do not need a paging file, and have indeed, disabled
it. The system runs perfectly, and has for the past four months.

If you have *sufficient* RAM, you do NOT need a paging file.

Jim

 

[Sept1967]

Ditto.

I have 3 PCs running XP Pro, 2 have 1 Gig each, and my main P4 has 2Gig. I
have never used a paging file.

One PC has been running XP Pro for almost 2 years now, 1Gig, NO page file.

What's the use. Why slow your PC down when you can run everything in memory.

 

[Nick Burns]

I have ran without one with no problems sept photohop7 bitched for not
having a page file. 1Gig ram

 

[Shane Steinmetz]

I guess the person was writing with the presumption that not many people
stock up highly on RAM. Just how much RAM does the average user have? 256
MB or less, from what -I've- seen.

Shane Steinmetz

 

[Shane Steinmetz]

RAM access is much faster than hard disk access, so using virtual RAM when
physical RAM could be used would probably only slow the computer down.

Shane Steinmetz

 

[Shane Steinmetz]

Wow. The program actually told you that you needed to having a paging file?

Shane Steinmetz

 

[Jim]

Yes, a great example of "not getting it".

Photoshop has no business looking at the paging file. The virtual memory
subsystem is suppose to be *hidden* from applications, indeed, it's even
worse in this case, Photoshop is actually looking for the *implementation*
(in the form of pagefile.sys)!

The application has no business delving into the VM or its implementation.
It should only be inquiring the OS about available memory. In response, the
OS should be calculating the available memory as RAM + VM (potential), or
whatever else Windows decides to use to emulate memory, perhaps NOTHING. If
the paging file is disabled, then naturally the result of RAM + VM = RAM.
That's *all* Photoshop or any other application need concern itself about.
If the call to return available memory is reported, for example, as 1GB, and
Photoshop doesn't like it, fine, it can scream its head off. If the OS
reports 16GB (4GB RAM + 12GB of *potential* maximum VM), and Photoshop
*still* doesn't like, it can scream it's head off, AGAIN. In the end, if
Photoshop is not happy, then it should inform the user there is insufficient
memory (not complain about the lack of a paging file). It might then
*suggest* (ONE TIME!) increasing RAM and/or offer additional information
that Windows can extend *physical* RAM through the VM subsystem and perhaps
provide some guidance how to achieve this through references to Windows
help.

Btw, it's not as if using VM that memory can't be exhausted! Suppose the
maximum limits on VM (pagefile.sys expansion) are still too low?! Photoshop
is still wrong, it would be much better off consulting the OS which will
then consider the true potential for expansion, NOT just the mere presensce
and/or current allocation of pagefile.sys. So now the application whines
ceaselessly because it's has foolishly built in a dependence on the memory
system implementation. Incredibly dumb, this is programming 101 stuff.

Jim

 

[Nick Burns]

I do forget the error, but Adobe told me it was from no page file. Turned it
back on and error went away. That was the only problem I encountered.

 

[Ron Martell]

The referenced article is WRONG ( http://aumha.org/win5/a/xpvm.php ) in one
respect, you do NOT need a paging file *if* you have sufficient RAM, period.

That is wrong.

You may not need a paging file if you have an *excessive* amount of
RAM; enough so that you can afford to waste a portion of that RAM
satisfying the memory address space requirements of the *unused*
portions of memory allocation requests. These unused portions can
easily aggregate to several hundred megabytes on a heavily used
system.

And in order to run without a paging file you *must* also accept that
fast user switching will not be available (the paging file is used to
roll out the RAM contents of previous users) and also *must* accept
that system failure memory dumps will not be available because these
are saved to the paging file on the boot drive, which is then renamed.


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

"The reason computer chips are so small is computers don't eat much."

 

[Ron Martell]

RAM access is much faster than hard disk access, so using virtual RAM when
physical RAM could be used would probably only slow the computer down.

Windows will not actually use the paging file - that is it will not
move active memory pages from RAM to the paging file - while there is
still unused RAM available.

What it will do is to use the space in the paging file to satisfy the
memory address space requirements of the *unused* portion of memory
allocation requests thereby allowing RAM to be used only for those
portions that are actually used.


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

"The reason computer chips are so small is computers don't eat much."

 

[cquirke (MVP Win9x)]

"Shane Steinmetz" <revieweroftime{REMOVETHIS}@silverinterlocution.org> wrote

I have 1GB of RAM and have disabled the paging file completely! And yet,
Task Manager shows that at least part of the kernal remains "paged".
Physically, that's impossible, since pagefile.sys doesn't even exist

Not really; it may be that parts of the kernel are paged out. They
don't have to paged out to disk, given that the original content
hasn't changed and can thus be paged in directly from the files that
the code was originally loaded from in the first place.

What's the rest of the PC's spec?

It may do; hard to say, given we don't know what your load is.

More memory only matters and is useful if you can actually use it. 256MB
is, frankly, only adequate for XP,

128M works OK too

But if you want to run apps as well as the OS, well...

I believe 512MB is ideal for the average user.

512M's nice. Right now I build with 256M or 512M, but with no less
than 120G HD space; processor typically Celeron-2.4

So monitor your usage, if you rarely if ever come close to 256MB in usage,
more memory buys you nothing. If you do (and it's highly likely you will),
more memory is one of the best investments you can make.

Only one caveat; don't add old RAM to an old PC you plan to abandon
soon, as you can't use that RAM in your new replacement.

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