Are there any downfalls to allocating the maximum amount of virtual memory?  Is there any reason why I should not? 

I found out that my laptop might be able to run FS better than my desktop if I can max out the virtual memory.

Virtual Memory is just space on your hard drive reserved for or containing program data which is used instead of RAM.

Either the programmer wishes to free system ram by using virtual memory (page file) or the program simply stores too much data to fit comfortably in RAM.

The program's access time for data stored on the hard disk is very slow compared to data held in memory, So critical functions are carried out in RAM while non time critical functions can be written to and accessed from the page file.

I think that's kinda how it works....

I think maxing out the page file (virtual memory) is not what you would call it. You simply need a page file reserve on your HDD large enough to hold all the paged data in a multi tasking environment.

You can also set the minimum and maximum size the same, say, 1.5 gb, that way, windows doesn't try to constantly alter the size of virtual memory as it does under windows management. I've never actually measured the benefit of this tweak.

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Why would think that? Virtual Memory is Vitual Memory, ie...... Page File. Allocating shared system RAM for an onboard video processor has nothing to do with virtual memory.

Windows automatically controls the "Virtual Memory" size, it constantly re-sizes the page file to what ever size it's contents are if you have the default setting of "System Managed"
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It doesn't work like that, it works as I explained above.

The only way to double your RAM is to add RAM modules to your mainboard. You can however, double your Virtual RAM, or Virtual Memory, or delete it all for that matter, (not recommended). Just remember that Virtual Memory is not virtual at all, it is real data taking up space on your hard disk.




 

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That is ok for systems with 512MB or less.  Once above that you need to use 2.5GB minus system RAM, or 2GB minus system RAM, depending on preference.

Well if youve got a raptor or a SATA drive it wouln't make that much difference.

Cheers
Cameron

Exactly, if you want to spend the money, a nice SATA/RAID solution helps a LOT by offering greater bandwidth for disk I/O. In addition, you could put the swapfile (pagefile) on a dedicated partition. A word of caution though, WinX platform doesn't always work as advertised when you "move" the Swapfile (Virt mem file).  This is especially true with XPSP2 and above.

BTW.. I find the forums here awesome! It's a pleasure to find so many so many folks that know what's going on and are willing to help!

You tell 'em Nick!

So, how well does windows manage the page file, and is there truly a benefit in setting a fixed page file size, has anyone measured or documented it?

I will answer and then drop this subject:


1.
It is very much possible to run XP and most programs with 2GB RAM and very little pagefile.  Some programs require a pagefile and won't work without it.

A:
I never said it was not possible… what I indicated is that it is not advised to do that because of those programs that need chunks of page file available to them. To give someone advice without knowing EXACTLY what is on their system and how they use their system is like doctor prescribing a medication and treatment without an examination, lab tests and observations, therefore it is best to NOT suggest something that can and WILL crash someone’s computer and to stick with what will not cause crashes, poor performance or other intermittent problems.



2.
To get absolute max performance and to stop XP using the hdd for memory you must turn pagefile off.  This elimates all jerkiness and loading lag.  XP will try and use only the system RAM and will be much quicker.  However because XP can't function very well without atleast a small amout of pagefile it is recommended that 200MB is set aside.

A:
Wrong… if you wish to run without the page file, the minimum to set aside is based on how much information you need in your memory dump for diagnostics. (System properties, Advanced, Startup and Recovery) for a minimal memory dump a 2mb page file is required. The page file space is needed for memory dumps based on your individual needs. a “minimal memory dump requires 2mb of page file space. If you want a kernel memory dump, a page file the size of the PM is needed, a full memory dump, PM x 1.5 page file is recommended. That is where Microsoft gets the PMx1.5 recommend page file size from.. but that is NOT set in stone, only a starting point

Next, please post the MSKB that states that a zero page file should be used for games or to increase windows performance. In fact MSKB’s say the opposite.



3.
XP uses 1.5xRAM to calculate its pagefile, this was based on an average system for the time which was about 256MB-512MB RAM.    

A:
Wrong… Microsoft set that because it is impossible for Microsoft Windows to analyze a system and determine the correct page file size for an individual use so it is based on a full memory dump for diagnostics and not based on “the good-old-days”



4.
2-3xRAM is not a very precise figure to use.  What about systems that have 128MB, giving 256MB-384MB virtual memory, that is not enough for that system.  Why does a system with more RAM need more pagefile?  A system with 2GB RAM would need 4GB-6GB pagefile!!!  That is way too much!  Any figure between 200MB and 500MB would be more than enough for that system and todays games.  

A:
You are again assuming everyone who asks the page file question is doing nothing but gaming. Also my recommendation covers everyone. Assuming someone runs 256mb PM and they use the 2-3x method, a static 500mb to 768mb page file covers them. Why? Because anyone running Windows and games or video content with only 256mb of PM will never see any performance gain from more than 500-768 static page file size… on the other hand they WILL most likely crash and burn on a zero or 200mb page file. If Windows needs more pagefile, it will let the user know in a message box. At that point they can increase the size again. http://support.microsoft.com/kb/315270/en-us

BTW.. I serously doubt anyone is booting WindowsXP and running FS9 or 128mb of memory.. even 256mb is silly to use with FS9, but anything is possible.


5.
Not too many people that have typical systems (for games etc...) do graphics editing too.  Most have a separate system for that stuff and that requires a different set-up like you said.  

A:
And that is why I do not recommend silly, internet fantasy, page file settings… because I do not know what the person uses their system for and I do not assume it either.



6.
Memory dumps are stored in C:\WINDOWS\Minidump not pagefile.

A:
Yes, it is written to the hard drive but that is why the settings for the page file are recommended in item #2 above, you said it yourself… you need the space for the memory dump which goes to the page file FIRST before it is written to the hard drive in “minidump” or the system will crash again when trying to write the minidump file.

If you wish to get right down to the hard line technical aspects of how to set a gauge pagefile size, it is done by using the performance counters and monitoring the memory I/O of a system… YES, you can run a small page file: IF you know for a FACT system does not need it. A  large page file (which is based on 2-3x PM) does NOT make Windows doggy or slow it down, that is a an internet MYTH, all it does is take up space However it ALSO functions as a prefetch and stores memory items from the PM which have not been paged in a period of time, therefore it does help performance by having those memory blocks ready for direct reload without looking all over the HDD for the separate chunks. That INCLUDES 3D Games (see next post)

Awesome Nick N! You covered ALL the bases on that one! Nice..  ;)  BTW, I'd hate to ask what that system of yours set you back (well, I can always dream of a system like that!)  :o ;D

Congo, to answer your question, the difference between static and dynamic page file should be determined by disk I/O. If your system is slow, and very fragmented, a static pagefile might make sense, but with todays powerfull systems, it's not such a concern. Here is a link to tweaking the pagefile if you wish. But if your not running a server where space and disk I/O is a premium, it's not worth the headaches that Win~ can throw at you.

http://support.microsoft.com/kb/314482/en-us

Changing the pagefile can wreak havoc with some imaging programs as well. So make sure you do a total restore and not incremental from an image file or you'll find issues.

Hope this helps guys,
Mick
PS: I love these forums cause it's a pleasure to chat with folks who KNOW their stuff and are willing to help others.  Thanks

Thanks Nick N, I wondered how FS9 would behave if moved to a dedicated partition, now I know. Sounds like you built one awesome server! I've built similar systems that were used in Assistive Technology Applications (home and office control / ECU) for customers with certain disabilities (IE speech in and out interfaces) linked to home control devices. Most of what I do with PC's is functional, gaming is new to me. You could use that unit to control your entire house, alarm, lights, intercom, phone system, whatever with a (relatively cheap) add on and it would still never hickup! Nice! 
Mick

Thankyou for your input gentlemen, I hope you don't mind if I cut and paste this for later reference.

I've seen the witchdoctors casting their curses too Nick N, seems they vasty outnumber PHD's.

Intriguing, informative. Good stuff.

Under memory dump settings, I've always set it to NONE, just because, no reason............ did I do bad?

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That memory dump is the reason Microsoft defaults to OS to a dynamic 1.5xPM. That amount is designed to cover all the bases and is not set in stone, it’s just a starting point. If you do not need diagnostic information the dump is not needed.

No matter how large or small the pagefile, Windows will always use PM first, meaning, the existence of the pagefile makes no difference in performance. The pagefile acts as:

1. An extension of PM (only if needed)
2 as a repository for chunks of memory (even if PM is not full) which have not been accessed in a period of time or to make room in PM (if it is full) for new chunks as they are called up.

....In other words if I (at 2gb PM, WindowsXP x64) am eating up 1.6gb  of PM booting a flight (not uncommon for my setup with PMDG 747, UT-USA/Canada, BEV, FlyTampa KSEA, lots of other extras + 100% on all sliders, etc, etc, etc) and during that flight I am accessing an estimated 2gb+ of additional scenery,... Each block of PM which is cleared to make room for more scenery files will get moved to the pagefile in a non fragmented complete set of files (at that point it is a swapfile). The advantage is that the blocks or chunks of stored scenery are waiting to be recalled (if needed) and since the system does not need to search the HDD for all the individual files the chunks (if needed) are reloaded with less I/O and therefore much better performance in the sim. It may ony need 250-500mb of that prefecthed information, but none the less it is faster (much less I/O) to retrieve it from a properly set up pagefile than it is to scower the HDD for all the individual files again. Even with the best HDD defrag the recalled files are 10x better organized for recall on a properly set up pagefile.

That happens if you have 128, 256, 512, 1024, 2048, etc, of physical memory installed and an established pagefile. The pagefile is not a waste, a performance dog, nor is it ignored. It is used as a swapfile no matter how much PM is installed.

WindowsXP x32 maxes out at 4GB PM and will allow a pagefile size up to 16 Terabytes in size.

WindowsXP x64 maxes out at 16 Terabytes PM   and will allow a pagefile size of 512 terabytes  


Being WindowsXP x64 memory access is different it is recommended the pagefile be much, much larger to do the same work as an XPx32 system.

Games do not run any faster with or without a pagefile however the pagefile can cut down on stutters from scenery loads. It depends on the game and the use.

Not everyone needs a large pagefile. The size of the pagefile is determined by individual system use, however, there is no harm or performance loss in setting the file to a 1-2 or 3gb size unless there is restricted disk space. It does nothing but take up space until needed.


After reading what I posted yesterday I realize I may have come off a bit harsh... it was not my intention to do so and I apologize if I offended anyone.  

One last item I did not address…

I understand the theory behind why it is said the PF can cause slow performance and shutting it down (if you have allot of PM) or reducing its size will fix the issue… The thought is by reducing disk I/O the system has more resources, however, all that does is put a finger in a hole of a leaky dam. It does not resolve the issue or make the system ‘truly’ faster. It creates a temporary placebo performance increase which is seen as an immediate improvement and therefore was considered good to do.

A few years ago I was having some stutter problems and experimented with pagefile size, including setting the system to ‘no pagefile’, which immediatly solved most of the stutter issues but caused other problems when the PF was needed, including intermittent stutters (not as bad as the original stutter issue) and other I/O slowdowns. Back then I was using a dynamic pagefile. With the help of an MS engineer who lived in my neighborhood (and the cost of a a few rum-and-cokes) I learned how to use the system performance counters to monitor where the I/O problems (disk and memory) were occurring. I learned that by setting a static size pagefile, then running an offline defrag on it was the key to resolving all the disk I/O issues. Moving the PF to another I/O on its own HDD further reduced I/O.

The fact of the matter is that if the PF is fragmented and dynamically changing the disk I/O is greatly increased. All of a sudden the blocks of stored memory chunks are 10x more fragmented and take more I/O to retrieve than simply recalling the files back up from their original location on the HDD. Over time as the PF becomes severely fragmented the system will start to really bog down. I defrag the PF once a month and also delete the PF every 90 days, reboot and rebuild it, and defrag it offline. Regular monthly maintenance is critical for proper PF performance.

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A good disk defrag software such as O&O v8 or Perfectdisk v7 will have that option. Once set you reboot the system and as it boots back up it will default to an offline defrag screen. It is also good to run a Windows disk check offline before defrags are run. This is done by:

My Computer,
Right click the boot drive, select properties
Select Tools
On the Error Checking window, click 'check now'
Put a check in 'Automatically correct errors' leave the 'scan and recover bad sectors' unchecked
click Start

Windows will prompt for a disk check at next reboot, select OK

reboot

the rest is automatic





As a side note, if you shut down the memory dump completely I do not think you will get an error blue screen which displays the file and memory address where the error occurred. I have always set mine to "small memory dump" just in case a BSOD decides to pop up. By doing I get the BSOD error message which can definitely help determine what caused the crash. A small memory dump only requires a 2mb pagefile be present on the boot directory. That is why I posted the need for the 2mb PF on the boot drive if you should decide to move the main PF to another HDD.

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Yep... it sure will!

That is another way to defrag a pagefile

Hey Guys,
     I wish to thank each of you for the time and effort in sharing your knowledge of this subject with me.     I am so pleased with this matirial that I printed the eleven pages for future reference .   My present PC is a real slow poke - - -but that will change this fall when the new FSX and Vista comes out.   [A PC special for FSX]      As I work on my "slow-poke" it educates me how to get the MOST out of what I have - - NOW and FUTURE.         AGAIN  I thank each of you.          caveman