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Virtual RAM Page file: how much? Needed?

Last response: in Windows 7
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December 1, 2011 2:55:52 AM

Hi. I got win 7 64 bit, 8 GB RAM on an Extreme mobo and a i7 960 chip running an 128GB SSD with two XfX black editions 5970s. I would like to know how much of virtual memory dedicated page file is best for speed in flight sim games, such as DCS A-10. How much should I allocated fr best performance? Is it a problem to have too much? The reason I ask is that when in A-10 DCS flight sim, every now and then the framertate drops disgnificabntly...for a minute or so, then goes back to normal. Doesn't seem to be a cause for this immediately apparent, but I'm wondering if it is the system shiftinf large amounts of data out of a lage sway page virtual memory file. Grateful any advice on the best size of virtual memory page swap files on hard disks. Thank you.

apoll

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a b $ Windows 7
December 1, 2011 3:01:12 AM

Use 3-4GB, its enough for most users : ) Leave it on the SSD.
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December 1, 2011 3:07:01 AM

Ok. 4 GB is how many MB? 400MB? Thanks.

t
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a b $ Windows 7
December 1, 2011 3:08:23 AM

Set it to min 2048MB to 4096MB
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a b $ Windows 7
December 1, 2011 3:09:10 AM

And leave it on the SSD!
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December 1, 2011 3:09:37 AM

Each GB is 102 mb so that is 4096 mb.
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December 1, 2011 3:11:40 AM

Ok. Great. Thanks very much guys! Much appreciated.

apoll
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a b $ Windows 7
December 1, 2011 3:13:19 AM

What andrewcarr meant, is that 1GB = 1024MB
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a b $ Windows 7
December 1, 2011 3:13:54 AM

apoll said:
Ok. Great. Thanks very much guys! Much appreciated.

apoll

Good luck apoll : )
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December 1, 2011 4:16:34 AM

NO NO NO!
Just disabled virtual memory, windows won't use the pagefile much as long as you got enough memory.
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a b $ Windows 7
December 1, 2011 5:11:01 AM

faxserverplus said:
NO NO NO!
Just disabled virtual memory, windows won't use the pagefile much as long as you got enough memory.

Not quite the truth for most people. W7 loves page file and will take advantage of it. Any Adobe program take advantage too. I would run out of 8GB of RAM in no time, sometimes I go out of 16GB of RAM when things get busy.

http://www.tweakhound.com/2011/10/10/the-windows-7-page...
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a b $ Windows 7
December 1, 2011 5:32:42 AM

first question is how much is needed and how much is allocated ? and how much is there to tap ?............ I run 8gigs of memory and set the max and minimum to 10000.
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December 1, 2011 7:32:45 AM

apoll,
The general rule that you use in this case is one and a half times your installed physical memory. In your circumstances, in which you have 8GB of RAM, you should set the page file to 12GB. All of this may not be needed, however this is a general rule that is used throughout systems. As for the best place to put the page file, it would be best to keep it on the SSD, since SSD's have faster access times and usually better read and write times.
Hope this helps.
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December 1, 2011 9:12:30 AM

it is recommented that your page file is 1.5x the amount in the computer. so it would be wise to have your page file at 12GB RAM
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December 1, 2011 10:11:36 AM

Recommended system requirements for all DCS series is 4GB ram. So with 8GB ram you should not be worry about virtual memory settings. If you are feeling uncomfortable with it, let windows decide which paging files to set automaticaly.

If you want to learn more about virtual memory, I recomend you to have a look at "Pushing the Limits of Windows: Virtual Memory", by Mark Russinovich at http://blogs.technet.com/b/markrussinovich/archive/2008...

The problem you are experimenting might be not be related to paging file, tough its symptoms are quite similar.







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December 1, 2011 8:23:13 PM

Thanks to all who hve replied. ost helpful.

apoll
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December 2, 2011 11:25:56 AM

nikorr said:
What about it?


Well you say you run out of 8gb in no time if you have no pagefile. But that article (though old) says a system rarely needs more than 6gb unless you are a power user, with 8gb and 12gb only needed in very extreme cases.
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a b $ Windows 7
December 2, 2011 3:11:17 PM

Dandalf said:
Well you say you run out of 8gb in no time if you have no pagefile. But that article (though old) says a system rarely needs more than 6gb unless you are a power user, with 8gb and 12gb only needed in very extreme cases.

I didn't say, that. I run out of it with the page file and if u have no page and get busy, RAM is going AWOL even quicker.

If people just browse and listen music and email, they are fine all the time with 4GB of RAM, that is most of the PC users, like my mom and sisters and most neighbors and people u work with, unless u are a PC technician : )

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a b $ Windows 7
December 2, 2011 3:13:42 PM

BTW, I have 16GB now and I am pleased to see that RAM $$$ are going down, because I can see how easy it would be to use 32GB.
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December 2, 2011 3:38:11 PM

I am of the opinion that one can never have enough ram, because even if you have 60gb you could just install your OS on it ;) 
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a b $ Windows 7
December 2, 2011 3:54:29 PM

Did u try the RAM disc? That's super SSD on steroids!
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a b $ Windows 7
December 2, 2011 5:01:48 PM

1: Leave the page file on system managed. Unless you are going to be working with a huge dataset, there is no reason to edit it in any way. Failing that, assuming sufficient HDD space, I set it to 2x the size of your main memory.

2: Be VERY careful when you go without a pagefile. Even without one, you are still going through the Virtual Memory subsystem, the only difference being every virtual address will be mapped to exactly one physical address.

Thus, even if something that is allocated is not being used, it is still taking up space in RAM, making it far easier to run out of room. [With a pagefile, those pages would be moved out to disk instead]. As a result, you will be using more RAM without a pagefile then with.
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December 5, 2011 10:19:51 PM

Hey guys...just to round off this very useful discussion...Itried a number of different configurations with pagefile for running the flight sim DCS A10. Findings were:

1) No swap file: simulation would not even run: got the back screen of death and had to manually boot back in.

2) A minimal swap file of 4096 or so: sim ran but REALLY choppy and like a slide show.

3) So I upped the swap file to something ridiculous: 60 000...and guess what: the sime runs very well with that. Seems to go against all the advice about swap files twice the suize of physical RAM, but go figure. That is what works for me.

FYI.

apoll
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a b $ Windows 7
December 5, 2011 10:23:01 PM

apoll said:
Hey guys...just to round off this very useful discussion...Itried a number of different configurations with pagefile for running the flight sim DCS A10. Findings were:

1) No swap file: simulation would not even run: got the back screen of death and had to manually boot back in.

2) A minimal swap file of 4096 or so: sim ran but REALLY choppy and like a slide show.

3) So I upped the swap file to something ridiculous: 60 000...and guess what: the sime runs very well with that. Seems to go against all the advice about swap files twice the suize of physical RAM, but go figure. That is what works for me.

FYI.

apoll

Nothing wrong with having plenty of swap file : )
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December 6, 2011 12:41:40 AM

Clearly not. But it seems the bigger the better. I do find that interesting. It seem this sim uses a HUGE amount of memory, including virtual. Thanks for you help in particular, nikorr.

apoll
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a b $ Windows 7
December 6, 2011 1:01:39 AM

Like I said, W7 loves it. Both, the RAM and the page.
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December 6, 2011 6:20:12 AM

I don't know too much about ram, but I do like playing video games and with 8 GBs of RAM, I believe you have enough to run your game fine. You may be more interested in checking if your box is properly cooled and if there are applications in the background hogging up your system's resources (security, browsers, music players). sometimes anti-virus/firewall updating/quickscanning can really slow a computer down.

EDIT:
I see you found a solution, but I personally doubt that the main reason why your game was lagging is because of a lack of virtual ram... 8gbs is quite alot already.
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a b $ Windows 7
December 6, 2011 8:05:40 AM

apoll said:
Hey guys...just to round off this very useful discussion...Itried a number of different configurations with pagefile for running the flight sim DCS A10. Findings were:

1) No swap file: simulation would not even run: got the back screen of death and had to manually boot back in.

2) A minimal swap file of 4096 or so: sim ran but REALLY choppy and like a slide show.

3) So I upped the swap file to something ridiculous: 60 000...and guess what: the sime runs very well with that. Seems to go against all the advice about swap files twice the suize of physical RAM, but go figure. That is what works for me.

FYI.

apoll



does that mean I hit the nail on the head ?
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a b $ Windows 7
December 6, 2011 2:50:35 PM

zircle said:

I see you found a solution, but I personally doubt that the main reason why your game was lagging is because of a lack of virtual ram... 8gbs is quite alot already.


Remember the swap file is for ALL programs that are currently running. Even if they are not activly doing anything, their resources still need to be mapped to the swap file, which can result in it getting very large. I've seen mine reach upwards of 12GB or so...[I have 8GB Physical RAM installed]

Just to go back to basics:

Win32: A single application can use up to 2GB of its Address Space [lower 2GB of Virtual Address is reserved]; System RAM limit is 4GB.
Win32 + 3GB Switch + Large Address Aware: A single application can use up to 3GB of its Virtaul Address Space [lower 1GB of Virtual Address is reserved]; System RAM limit is 4GB.
Win32 + PAE + Large Address Aware Application: A single application can use its entire 4GB Virtual Address Space; system RAM limit is 64GB.

Win64 + 32-bit EXE w/o Large Address Aware: A single application can use up to 2GB of its Virtual Address Space; System RAM limit is 192GB [limited by OS]
Win64 + 32-bit EXE + Large Address Aware Application: A single application can use its entire 4GB Virtual Address Space; System RAM limit is 192GB [limited by OS]
Win64 + 64-bit EXE: A single application can use up its entire 64-bit Virtual Address Space; System RAM limit is 192GB [limited by OS]

Most apps are 32-bit, so depending on the setting of the Large Address Aware flag, even on Win64, 32-bit applications are limited to either 2GB [Not LAA] or 4GB [LAA], regardless of installed RAM.

Without a pagefile, all Virtual Addresses must be mapped to a single Physical Address. So if you have 8GB installed, all your applications combined can never use more then this amount at any one time, or the application that next asks for more space allocated will crash [due to an unhandled error when malloc fails...].

With a pagefile, Virtual Address will be mapped to RAM only when the data stored in those address needs to be read/written to. As a result, teh amount of RAM in use at any one time is actually very, very small [Avaliable RAM], even though the majority of RAM has been used at one point or another [Free RAM]. In other words: Avaliable RAM is RAM that is able to be used, Free RAM is RAM that have never been used by any application.

For example, if I created a 1GB buffer, and I don't use it, with a pagefile, none of that 1GB gets mapped into active memory. The Virtual Addresses are reserved, but not mapped into physical addresses. Without a pagefile, each of those 1GB of Virtual Address MUST be mapped to a PHysical Address, costing you 1GB of RAM even though you haven't populated a single bit in the buffer.

Point being, sicne you are going to go through the Windows Virtual Memory subsystem no matter what you do with the pagefile, you may as well leave it on. And the majority of the time, "System Managed" is good enough, since the pagefile will grow as needed. [I usually set the maximum size to 16GB, which is a "sane" limit for running no more then one heavy app at a time].

Edited to clean up some statements and remove general confusion
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December 15, 2011 12:09:10 PM

gamerk316, you got the basics wrong :) 
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a b $ Windows 7
December 15, 2011 4:18:13 PM

^^ Nope. I'm referring to a singular application, not the amount of maximum memory avaliable to the system as a whole, though I did make a correction to the 3GB switch (forgot you still need the LAA flag to use the extra GB of Address Space). (I'm also ignoring AWE, for simplicity)
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December 15, 2011 6:18:45 PM

Not a big deal, but it is the upper 2 GB that is reserved to the kernel, and pae doesn't grant access to more virtual address space. The user space is still 2 or 3 GB.
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December 16, 2011 12:27:53 AM

Best answer selected by apoll.
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a b $ Windows 7
December 16, 2011 12:42:18 AM

Thanks for the vote apoll : )
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a b $ Windows 7
December 16, 2011 12:42:36 AM

This topic has been closed by Nikorr.
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