Virtual Memory ... worth to modify ?

[Cov]

As you may know, our HDDs (SATA/150) have transfer speeds of approx 118 MB/s.

My DDR2-800 Memory is significant faster ...




When I check under ...

Start › system › advanced system settings › performance › settings › advance › virtual memory › change

... how much virtual memory has been assigned in my system, I get the following info:

• By default, “Automatically manage paging file size for all drives” setting is selected so that Windows Vista system can manage the paging file without user’s interruption.
• If you want change the paging file size, move the pagefile.sys to another drive, or disable virtual memory paging, uncheck the check box of Automatically manage paging file size for all drives.
• Select and highlight the appropriate drive that users want to change the paging file settings under the box of “Drive [Volume Label]“.

• To fix a permanent size for the paging file, click on Custom size button, and set the values of Initial Size (MB) and Maximum Size (MB).
• Both values can be of same size to make the size of pagefile.sys static.
• Then click on Set button.

• System managed size is useful for users who do not want pagefile.sys to locate on system drive root and want to move its storage location to another drive, but still want Vista to dynamically manage and allocate the drive space for the paging usage.
  
• To move the paging file to another drive, click on No paging file radio button, and click on Set button. Then select a different drive to set a new pagefile.sys with custom size or system managed size.
  
• To disable paging file or virtual memory, simply set no paging files on all drives.

At the moment I have 4 GB physical RAM (Vista x86) and I'm aware that the more RAM you have, the more Window assigns as paging file.

If we consider about 4 to 5 GB memory to be reserved for the swap file and I had 8 GB RAM (Vista x64), couldn't I make Windows use my RAM instead of the HDD ?

According to Everest are only about 25% of my RAM used after Vista has booted up.

3.25 GB - 25% would mean up to 2.5 GB unused RAM

Has anyone tried this out yet ?

[Blaineoliver]

Some games refuse to run without pagefile. Try some see if you get a performance increase.

[Tonka777]

Bear in mind that each game/app is limited in address space by Windows, this is usually less than 3Gb, as there is a 3Gb switch for xp and Vista to allow it to use more.

Also, i know that Windows likes to keep a large proportion of your Ram free just in case you are thinking about launching something else, i cant remember the specifics, hopefully someone else will!

[Cov]

Was just thinking about Vista's Ready Boost but that is limited to max 4 GB additional memory from a USB device.
Then I thought about using the whole of my 8 GB USB stick instead of the HDD, but looking at the transfer speed it seems as a no-brainer:

USB 2.0 has a raw data rate at 480Mbps = 60 MB/s.
Besides this, doesn't flash memory "wear out" ?

[WhiteGiant]

I've been trying to think of something to do with my 8gb, will watch closely.

[Mblaster]

I have 4gb of RAM on Vista x64, and I removed the page file.

Had no problems at all, although didn't really do any benchmarking to test if it improved performance.

[Singh400]

The pagefile is there for a reason. Windows won't operate correctly without it. I've got tons of HDD space so I've got a 6GB static pagefile.

[shbris]

yep necessary evil

[digit]

If you want to make a slight performance difference to your page file, having it on a different drive to the one windows is installed on is a good plan. If you really wanted faster performance on your primary hdd, switch to an SSD. Provided its using the newest chipset it would make a difference to access times.

[Cov]

You can indeed turn off the paging file 100%.
And no, Windows will not just enable it again, which is why Windows/applications crash in funny ways, if all memory gets eaten up.

Mark Russinovich, if you trust him as a source, writes this in his Windows internals books.
There are also many others trustworthy sources that say the same.
And if you investigate your own system, you'll see that it is the truth.

My window Vista Ultimate 64 bit with 4 gigs of RAM runs perfect without paging files.
I run 3ds Max 9, and Adobe Master Collection as my primary software to perform my work.
Games Microsoft Flight X, and spiderman 3.
I just concluded that with 4 gig why have a need of paging files, and my programs at least seem to open faster.

Read this for specifics: http://support.microsoft.com/kb/889654

Important line:
"When no page file exists, or the page file is insufficient, the system reserves some virtual memory in the physical memory for its paging needs."

In translation, if you don't have page file paging memory will be still used in physical memory which is surely faster then on HDD.
And due to fact that paging is done even if there is a LOT of free memory there are some gains when working without PF.

Which applications need PF to work I really don't know and as a programmer I would really like to see the problem which can't be solved without using PF.

Anyway, I work with 4GB XPx64 and without PF.
I have one Linux VM (with 1GB reserved) working almost all time except when playing games.
And I tend to play high load games like Crysis or COD4 in 1680×1050 on ultra high settings…

Disabling PF gives no visible performance increase generally, for example in some rare occasions you will spare your self waiting to copy large file when Windows suddenly decides to write large chunk of data to PF.
Or after long inactivity without you will not need to wait for windows to restore PF data from disk as it will do instantly from memory.

The most important reason I don't use PF is because my HDD is a LOT LOT quieter without it.

Anyway gains and risks for disabling PF are minor, so I recommend disabling it and if after 1month (which is generally the time to populate your system with mostly used applications) you don't experience any problems leave it disabled. In this period save often

Regards..

Another consideration is security.

With paging file, Windows can potentially save your files to disk.
These files on HDD can be recoverable. Without paging files, anything in memory will basically not be "logged".
That is why for some security programs, they also recommend turning paging off to prevent having a copy of your sensitive document/data to be saved on a HDD.

Virtual memory is FAR slower than physical memory.
If something gets move into the virtual memory, and you have to use it, you'll notice a delay in accessing whatever application got moved.
Windows will move things to virtual memory (WHETHER OR NOT YOU HAVE PLENTY OF PHYSICAL MEMORY FREE) simply because it hasn't been active for X amount of time.

Virtual Memory is a great safe guard against memory leaks, however, Windows' behavior on moving application to virtual memory even before the physical memory is reaching capacity is really annoying and a performance hit.

If you are one of the few that have frequent FBI visits or do REALLY REALLY private stuff on your computer, you can set the paging file to empty out during shutdown, however, this significantly increases shutdown time and isn't recommended.
It's also easily possible that the FBI would be able to access it even after it has been deleted (even after a secure "shred-style" delete), so it is likely not worth the trouble.

ect ect ...

[cheesemp]

I've found real performance improvements spanning my page file over two disks on my work machine. Its only got 2Gb of RAM but putting the swap onto both drives resulted in visual studio almost doubling in responsiveness - It was almost unusable otherwise.

I doubt you'd see any real gains taking it away although I would recommend setting it to a sensible static size so it doesn't fragment to much.

[DDY]

I've turned the page file off to re size a partition under Vista but forgot to turn it back on after. I'd constantly get windows notifications that my memory is running critically low, save work and close applications. Ignoring this (deliberately) I fired up another application and the machine locked up. Even with 2GB RAM, page file is essential.

[Singh400]

ect ect ...

Fascinating that Mark says that. Mark is like God of Windows. His word is Law.

I'm gonna disable the page file tonight and see what happens...

Oh and it's etc etc..., not ect ect

[Mblaster]

Fascinating that Mark says that. Mark is like God of Windows. His word is Law.

I'm gonna disable the page file tonight and see what happens...

Oh and it's etc etc..., not ect ect

It's not going to be all that exciting, unless you don't have much memory and your PC crashes

Would be interesting if someone (someone less lazy than me) benchmarked it to see if theres actually any performance gains, and where/how much etc.

[CaptainCrash]

Fascinating that Mark says that. Mark is like God of Windows. His word is Law.

I'm gonna disable the page file tonight and see what happens...

I think he just said it was *possible* to completely disable the pagefile without Windows automatically re-enabling it - he didn't necessarily say it was a good idea, unless I've misunderstood something.

[H]ard|Forum willy-waving if anyone's interested...

[Paul Adams]

You are unlikely to see significant benefits from resizing, removing or relocating the pagefile(s) on Windows clients, I could maybe see a reason for tuning it on servers but even then after baselining to ensure it actually makes a positive difference.

By having no pagefile you can prevent some apps from launching at all.

By relocating the pagefile to a drive other than the system drive you may gain a tiny bit of performance for app loading times or under heavy memory pressure, but at the cost of being able to produce a memory dump if a bluescreen occurs.

Resizing the page file on the system drive to less than ~1GB can also make a memory dump impossible if a bluescreen occurs - this is where the populated contents of physical RAM get dumped.


Understanding why paging occurs can be useful - it is a natural housekeeping job done by the kernel to free up limited resources (physical RAM) which is in use but has not been used recently (or tagged as "lock in physical memory" by the developer using APIs).

Where XP used to free up pages of physical memory and have a large list of empty pages, Vista would rather use these empty pages for caching - to prevent the need for accessing the page file to pull virtual memory contents back from disk.

If physical memory used hits a threshold, this cache can be reduced to satisfy memory requests from apps, so it's not preventing anything from working as intended.


Also, on the ReadyBoost topic - this is pure for file caching and not a replacement for the pagefile.
The pagefile contains "valid data mapped in the system virtual address space" and so if it suddenly vanished then it will likely cause a bluescreen.
USB memory sticks are intended to be removable - even without warning - so by using them only as a fast version of files read from disk it does not matter if it gets ejected suddenly as the data can still be obtained from its original source.


From personal experience (not measured benchmarks) I have found much more perceptible performance gains from using suspend-to-RAM instead of startup/shutdown - as the cache isn't flushed so when you resume it still contains valid, usable data without needing to go to the disk.

I have not seen any empirical evidence that removing, resizing or relocating the pagefile helps under "normal circumstances" - only synthetic lab stress tests which don't help in the real world.
There will be people that will argue with that, of course