Virtual Memory

[The Ruptured Duck]

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.

[ctjoyce]

Well it gives more memory to your video card, but takes it away from system tasks. So you may have a 256mb gfx card, but only 256 system. I would only recomend this is you have a gig or more.

Cheers
Cameron

[congo]

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.

[ctjoyce]

Ahhh congo I think hes talking about setting his video card memory in his BIOS. If so thats not the page file This is just running system memory for your video card. However once your in windows you can use the pageing file to get you dubble the RAM.

Cheers
Cameron

[congo]

Ahhh congo I think hes talking about setting his video card memory in his BIOS.

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"

However once your in windows you can use the pageing file to get you dubble the RAM.

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.

[NicksFXHouse]

Best bet is to set Virtual memory to a static size 2 or 3 times the physical memory... and if you are running Windows x64, set it to a static size 4 times the physical memory.

Run an offline defragment of the system files after making the change

[Delta_]

Best bet is to set Virtual memory to a static size 2 or 3 times the physical memory... and if you are running Windows x64, set it to a static size 4 times the physical memory.

Run an offline defragment of the system files after making the change

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.

[Mick_C]

Nick N and Congo give excellent advice here. and I agree with them and the formulas. Just remember that "Virtual Memory" is just that "Virtual". IE... it uses physical HD real estate to mimick RAM.

[ctjoyce]

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

Cheers
Cameron

[congo]

SATA drives are barely any faster than an ATA-IDE drive in real usage. Raptors are a step up, but they are still a HDD, absolutely no substitute for RAM.

What's the difference between whether a HDD is 200 or 250 times slower than a RAM data access/write? HDD's are a huge bottleneck, now more than ever.

I'm guessing that programmers can run everything in memory, but they must cater to the realities of the average user's RAM capacity. So, you are always going to get Bottlenecking from HDD access until/if we ever see programs/sims/games running totally in RAM, (I'm thinking that 4gb of ram may not be enough for new games.)

This is possibly why those who have tried to shut off the page file end up with problems. The programmers are calling up page file access routines so they don't crash everyone's RAM limited systems, and when the system reports no page file, the program dies or shuts down with an error.

[Mick_C]

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).

[NicksFXHouse]

[quote]

That is ok for systems with 512MB or less.

[congo]

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?

[Delta_]

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.

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.

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

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.

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.

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

[NicksFXHouse]

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.