Virtual memory-XP

stevec46

Active Member
Hi,
I have a couple of questions regarding virtual memory:-

1. If you install additional RAM into a machine running XP, will it automatically change the virtual memory size or do you need to do this manually ( I do know how to change it, but just curious to know if it does it automatically)

2. As I understand it Virtual memory is an area on the hard drive used for swapping programs in and out of RAM, so why do you get Virtual Memory low messages?Is it because when you install some equipment, say a web cam, it installs a driver to memory (I think that is normal memory?), so if you get a different web cam and don't remove the original, you will have 2 device drivers taking up RAM, leaving less for programs to run in, therefore need more Virtual memory.

How can I check what Device drivers are being put into memory and remove them if not needed?

Thanks

Steve
 

stevec46

Active Member
Actually I can answer question 1:-No,XP doesn't automatically change the page file size, I suppose the question now is, should you change the page file size?
I guess if you put in more RAM then the pro grammes have more RAM to run in.

But if you have a large hard drive, with loads of room, why not just bump up the sizes anyway?

Another question, if you keep adding stuff to you hard drives (Photo's etc) when you start running out of room on your hard drive, does it reduce the page file to allow more room for storage? I don't think so, but just curious.

If any one has any thoughts on this or my questions in main post the please reply.

Thanks

Steve
 

The Dude

Distinguished Member
Virtual memory is one of the first things I turn off (ie no paging file), providing the machine has at least 512mb RAM. ;)

WinXP will run OK in 256mb with VM turned off (XP itself requires just 160mb), but if you have any hungry apps that you use then 512 is really the bare minimum, and 1024mb recommended. :)

FWIW, the machine I'm typing on now, has 512mb, no VM, and runs 24/7/365.

I run Firefox, Thunderbird, Foobar, Ableton, JRiver....... all the usual suspects, without any memory issues at all.
I do have my windows services in good order though, you can save 15mb(?) just disabling the junk that you don't use...
 

Singh400

Distinguished Member
It is highly recommended that everyone has a Virtual Page File - even people who have over 2GBs of RAM.

Why? Because Windows XP needs it. Simple as.

http://support.microsoft.com/?kbid=555223 said:
Virtual Memory is always in use, even when the memory required by all running processes does not exceed the amount of RAM installed on the system.

In modern operating systems, including Windows, application programs and many system processes always reference memory using virtual memory addresses which are automatically translated to real (RAM) addresses by the hardware. Only core parts of the operating system kernel bypass this address translation and use real memory addresses directly.

It is recommended that your page file be set at 1.5 & 3.0 times for min and max of your RAM. For example, if you have 512 Mb of RAM, your page file would be set up like this:

Min = 512 * 1.5 = 768 MB
Max = 512 * 3.0 = 1536 MB

But, you can set your page file to one size, so you can save your CPU cycles. I've got mine set to 4096 MB (4GB).
 

The Dude

Distinguished Member
No it doesn't, simple as. :)

Have you actually tried this? what happens to your PC if you disable VM?
What happens to PF useage? What happens to Physical memory useage? What happens to CPU useage?

Don't just guess/google your answers.... go find out for real. :smashin:
 

Singh400

Distinguished Member
The Dude said:
No it doesn't, simple as. :)

Have you actually tried this? what happens to your PC if you disable VM?
What happens to PF useage? What happens to Physical memory useage? What happens to CPU useage?

Don't just guess/google your answers.... go find out for real. :smashin:
:rotfl: You think you know better than Microsoft? The people who built Windows XP! You think you know better than the hundreds of MVPs who all recommend that you have a page file?

I have tried XP without a page file, and it doesn't nearly run aswell as it does with a page file. Not having a page file is just plain wreckless and could be damaging to your overall system performance.

@stevec46: You can either believe Microsoft and it's MVPs or just a small minority of people who think getting rid of the page file is a good idea. :rolleyes: Your choice.
 

The Dude

Distinguished Member
:rotfl: You think you know better than Microsoft? The people who built Windows XP! You think you know better than the hundreds of MVPs who all recommend that you have a page file?
:rolleyes:

Oooohhh... MVP!! If you know what MVP means then you must be right.... :lesson:

Funny how the 'Windows XP experts' at Microsoft have been recommending the same pagefile settings you quoted, since 1994 ;)

If you have enough RAM in your PC for the applications you are trying to run, then it doesn't make a blind bit of difference if you have a pagefile configured or not. In theory your PC should run faster without a pagefile... in reality, all it will do is maybe make your laptop battery last a bit longer.:)

People are welcome to believe whichever websites they like, I'll stick to believing my own eyes. :)
 

Steve.J.Davies

Well-known Member
Virtual memory = the logical address space in which a program is considered to run.
The physical implementation is a different question. With enough real storage (memory chips on the motherboard) the backing store (the disk space) will not be needed for Windows. Unlike some Operating Systems which must have a certain amount of page space on disk (and in some cases certain number of page spaces some dedicated for certain system uses).

The disk space used is NOT part of virtual memory.
Virtual memory is just that - Virtual.
The paging space on disk is part of the background mechanics of the implementation - in some implentations (and Windows is one of them) enough real storage and you don't need the page space.

The Dude is correct.

For those that just listen to (single) vendor speak I suggest a read of any of the Classic Operating System design books - amongst others... I recommend Harold Lorin.
Or check out the free (and huge) on-line library of manuals on the IBM website. But just check out the general descriptions of paging systems and how virtual storage works. If you get to a manual that starts talking about all the diferent kinds of storage used in an IBM mainframe it will get hairy as there quite a few - and it is only relevant to mainframes (and the sysprogs that drive them).

-------------editted addion-----------
"It is recommended that your page file be set at 1.5 & 3.0 times for min and max of your RAM"

can't let this go un responded to.

Calculating real and backing storage requirements is a LOT more complex than this in the real world - and multiplying the amount of real by a fixed number to get a magic answer for the size of the backing store is definately NOT the way.
It doesn't help the M/S call the paging space on disk 'Virtual Memory' because it is not Virtual memory - it is just backing storage for paged out pages. Again the perils of just mimicing vendor speak - one of which is that without knowing how things actually work is that you propagate falsehoods generated by improper nomenclature and the absence of independent critical means.
 

Rygar

Well-known Member
It’s different strokes for different folks. Really depends on what the PC is being used for. Microsoft has to give very general advice to cover all the variables and novice users. More advanced users do not need to follow every bit of advice from Microsoft, as they know better than Microsoft how their own system will perform in conjunction with other applications they have running on their own machines, and their own particular hardware set up.

If the page file was such an important feature of XP, Microsoft would not make it so easy to turn off.

At the end of the day unless you are stuck for hard drive space, just let windows decide on what size of page file to have and forget about it.

If you really feel you want to turn it off, go ahead and do so. If your system becomes unstable or slow, turn it on again.

FWIW I currently have 1GB of ram and usually run my system with it switched off. I tend to keep system restore switched off as well....Not for any technical reasons, just because it saves me about 14GB of hard drive space , which is good as I'm too stingy to splash out on a bigger hard drive :D
 

MarkSS

Active Member
Singh400 this is one of those things you'll have to accept that other people know more about. Steve is 100% correct and if you had any knowledge of what actually occurs under the covers you'd be in agreement as well.

Are you running 4 instances of visual studio, 8 instances of Photoshop and several video editing applications at the same time to warrant a 4gb pagefile?

1. If you install additional RAM into a machine running XP, will it automatically change the virtual memory size or do you need to do this manually ( I do know how to change it, but just curious to know if it does it automatically)

By default windows is configured to adjust the paging file as required, the average user doesn't need to worry about it. There is a minor benefit to be had from deleting the pagefile, defragging then fixing the page file to a set size (to ensure its a contiguous block on disk) if you use lots of memory hungry applications and have limited RAM but generally, don't worry about it.

2. As I understand it Virtual memory is an area on the hard drive used for swapping programs in and out of RAM, so why do you get Virtual Memory low messages?Is it because when you install some equipment, say a web cam, it installs a driver to memory (I think that is normal memory?), so if you get a different web cam and don't remove the original, you will have 2 device drivers taking up RAM, leaving less for programs to run in, therefore need more Virtual memory.

Thats not the way drivers work so again don't worry about that one. Are you getting vm messages? If so, how much RAM and disk space do you currently have and what was running when the message appeared?
 

Singh400

Distinguished Member
Singh400 this is one of those things you'll have to accept that other people know more about.
No, everybody is entitled to thier own opinion - on if you should have a page file or not. Nobody is right or wrong. They think they know more, when they really don't at all - don't get me wrong, I'm not pretending I know either.

A lot of people agree with me that you do need a page file (not on this forum, another one).

Anyway, we've all said what we've wanted to say. Therefore I'm done & dusted with this thread.
 

stevec46

Active Member
Sorry to have caused disagreement :thumbsdow

One of the reasons for asking was to have a better understanding of VM, another is the fact that my sister in law is getting low VM message, so do I just pump up VM? I have no idea how much RAM she has (she has not brought Laptop to me yet), but as Laptop is several years old, I guess it could do with more, so if I fit more, do I adjust VM? Or leave it as it is and show her how to adjust it, my concern is that she may continuously adjust and mess with other things..

Thanks

Steve
 

Steve.J.Davies

Well-known Member
stevec46,
Micros**t calls the pageing file on disk Virtual Memory. They are wrong to do this but being wrong never stopped them.

to reduce demands on the page file you have to reduce your demands for over comitted real memory (reduce your 'working set' us propeller heads call it).
Two ways to do this -
1) make sure you are not running 'too many' apps for the amount of memory you have
2) Increase real memory. With current prices best bet is max out memory in her PC.
if you still page like crazy then you have to reduce demand by running less apps. there are some very hungry apps out there and many are written to assume they are the only real (or main) app on the PC. Windows doesn't give the user many levers to adjust these things unlike the 'real' operating systems out there.

If you go into task manager you can get it to show you what apps are sufferring the most page faults. Upgrade memory, increase the pageing dataset size and if prob still persists look in taks manager and tell us who the victims of paging are.

laptops (and PCs often supplied with low memory to achieve price point so investigate this first.
if you have probs post back with model name etc and we will get you there.

no apologies needed from you BTW

HTH
 

drummerjohn

Well-known Member
My experience is simple. I do not use a paging file on any of my PCs and the result is a faster system. My PCs below...

HTPC - 512Mb
Media Server - 512Mb
Games PC - 2Gb
Laptop - 512MB
Wifes PC - 512MB
Sons PC - 512MB

Been doing it this way for 3 years. No problems so far.
 

Steve.J.Davies

Well-known Member
yep it will be. ther are real reasons for this, all about the way Operating systems and virtual memory work. Less interrupts, less overhead = more CPU for your apps.
the best paging operation you can do is not to do one. as long as you got enough memory.
i run with 1Gb and although I have spare memory nearly all the time i can still suffer page faults. trouble is the odd occassion ehen I know I am going to max out memory - generally will into some large processing run which will then abend.. - I forget to activate the page file in windows first. so I run with a page file on all the time just for these odd occasions. Nothing wrong at with your policy, if it wasn't for my occasional needs I would run the same way.
 

The Dude

Distinguished Member
To think.... just how much money we must earn between us, and not one of us knows the first bleedin' thing about how Windows XP works :(


I knew I should have gone on that MCSE bootcamp.... :lesson:
 

MarkSS

Active Member
Similar here:

Old laptop (used to stream media): 512mb
Dev laptop: 1gb
HTPC: 1gb

Development laptop is the only one I occasionally have to enable the pagefile for. Today running two VS instances, SQL EM + QA, MSDN, Outlook, Firefox etc etc and I hit a total of 850mb, no problems at all.

HTPC (running SageTV) quite happily runs Doom3 or Far Cry while recording 4 channels in the background, again no problem at all.
 

DoktorAvalanche

Active Member
stevec46 said:
One of the reasons for asking was to have a better understanding of VM, another is the fact that my sister in law is getting low VM message, so do I just pump up VM?

Just ask her how much space is left on the hard drive.
I have experienced this (on an ancient p3 with only a 5gig drive); it could be that your sister in laws drive is too full.
The error occurs when the only space left to write to the hard drive is the chunk allocated for the VM.

In-laws, bain of my life...:rolleyes:
 

stevec46

Active Member
Thanks for all the replies :thumbsup:

I will have a look at my sister in laws laptop next time I see her (could be some time yet..) and go from there, will re-post if I need to.


Steve
 

springtide

Distinguished Member
Windows does have a tendency to use VM when it's not required, but there is registry key that can be modified to keep more of the Core system in RAM - this came from a MS TechNet article......(but I've now lost the number!).

Obviously removing the page file completely will stop all un-necessary VM usage, but for those of you who'd still like to keep it - just in case!

Does (or should I say did) seem to do this trick - fixed my "dropped frames" issue a number of years ago while I was trying to do DVI Capture with only a single HD.

----------------------------
Keep the core system in RAM
----------------------------
Windows XP takes portions of the operating system, applications, and data files that aren't currently needed in RAM and temporarily stores the data on the hard disk in the paging file. During a normal computing session, Windows regularly moves data back and forth from RAM and the paging file.

If you have a considerable amount of RAM in your system--512 MB or more--you can improve system performance by preventing the OS from sending user-mode and kernel-mode drivers, as well as kernel-mode system code, to the paging file.

You can do so by changing a setting in the registry. Here's how:

Launch the Registry Editor (Regedit.exe).
Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\
Session Manager\Memory Management.
Double-click DisablePagingExecutive DWORD value.
Change the value in the Value Data text box from 0 to 1, and click OK.
Close the Registry Editor.
You may need to restart the system or log out of Windows XP for the change to take effect.

Note: Editing the registry is risky, so be sure you have a verified backup before making any change!
----------------------------
 

Steve.J.Davies

Well-known Member
The Dude said:
To think.... just how much money we must earn between us, and not one of us knows the first bleedin' thing about how Windows XP works :(


I knew I should have gone on that MCSE bootcamp.... :lesson:

That may be a 'because' rather than a 'despite'.

As for how Windows works, its actuall quite simple. Badly.

When M/S had to write their first Operating System on their own they couldn't do it and had to bring in expertese from the people that wrote VMS (a DEC system).

Hands up what version of windows that was ?
 

Steve.J.Davies

Well-known Member
MarkSS said:
Similar here:

Old laptop (used to stream media): 512mb
Dev laptop: 1gb
HTPC: 1gb

Development laptop is the only one I occasionally have to enable the pagefile for. Today running two VS instances, SQL EM + QA, MSDN, Outlook, Firefox etc etc and I hit a total of 850mb, no problems at all.

HTPC (running SageTV) quite happily runs Doom3 or Far Cry while recording 4 channels in the background, again no problem at all.

Would it be worth posting your HTPC system setup in the Forum ?
 

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