8800GTX breaks 2GB memory barrier in vista?

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8800GTX breaks 2GB memory barrier in vista?

Postposted on Thu Jul 19, 2007 3:13 pm

I just purchased an 8800GTX last weekend, and it arrived last night. I'm loving every bit of it. Except for something I just read about today on Anandtech. Read This and as a follow up, Read This.

So basically what this is saying is that with new video games, if you have an 8800GTX and Vista, you are going to be seeing a lot of crashes either now or in the near future with no current, desirable, fix.

I have Vista because its asinine to have a DX10 card and not have DX10.

I read TR a lot, and hardly ever read Anand. Wish I would have heard about this prior to my purchase. I probably would have just bought the 320MB 8800gts. I would love to hear what the TR guys have to say about it.
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Postposted on Thu Jul 19, 2007 4:00 pm

The article does say that by opting for 64bit Vista you can effectively double the size of the virtual address space (4GB), so you can avoid issues plaguing 32bit games. 32bit games will not be designed to use more than 2 GB of virtual memory, and for 64bit games it is not an issue.
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Postposted on Thu Jul 19, 2007 4:00 pm

I don't have the greatest tech level, so while I'm still trying to make sense of the first link, am I correct in my understanding that the follow-up suggests that Vista uses VRAM more efficiently?
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Postposted on Thu Jul 19, 2007 4:02 pm

I frequently get the "ran out of memory" error in Vista all the time with 2GB's.. :-?
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Postposted on Thu Jul 19, 2007 4:04 pm

M3ZCL4N wrote:I don't have the greatest tech level, so while I'm still trying to make sense of the first link, am I correct in my understanding that the follow-up suggests that Vista uses VRAM more efficiently?
Nope, only that XP uses significanly less virtual address space, cause unknown but speculated it has (at least partially) to do with virtualization of video ram in Vista.

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Postposted on Thu Jul 19, 2007 4:07 pm

I guess I need to go 64-bit now, even tho I only have to 2GB of ram, heh. Then I need to hope that all the games that cause this problem have that special code flag that will allow it to use more than 2GB of address space. *sigh* 64bit support is just not mature enough yet, and I'm dredding going to it, but I guess this is basically saying that if I want full eye candy with my cool video card than I need a 64bit OS.... :(
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Postposted on Thu Jul 19, 2007 4:08 pm

M3ZCL4N wrote:I don't have the greatest tech level, so while I'm still trying to make sense of the first link, am I correct in my understanding that the follow-up suggests that Vista uses VRAM more efficiently?


You have to remember that DX10 incorporates a type of hypermemory/turbocache with the installed graphics card.

Virtual memory is also required by DX10, meaning that the GPU can now page data out to system memory if it runs out of memory on the graphics card



When I had an 8600GT (256) installed in my rig (A64 X2 4600+, 2GB DDR2-800) dxdiag reported the available video memory at 1GB (256MB dedicated, ~700 shared). From the chart, it looks like the less video ram you have onboard your graphics card, the lesser the load of the overall system memory.
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Postposted on Thu Jul 19, 2007 4:50 pm

Going to 64bit doesn't double it. If you went from 32bit to 33bit, that'd double it.

2^32 = 4294967296 bytes
4294967296/1024 = 4194304 kB
4194304/1024 = 4096 mB
4096/1024 = 4gB
4294967296/1073741824 = 4GB

2^64 = 18446744073709552000
18446744073709552000/1073741824 = 17,179,869,184 gB.
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Postposted on Thu Jul 19, 2007 11:31 pm

I have Vista because its asinine to have a DX10 card and not have DX10.

Is it also asinine to have a bitchin' fast DX9 card?
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Postposted on Thu Jul 19, 2007 11:38 pm

heruur wrote:I frequently get the "ran out of memory" error in Vista all the time with 2GB's.. :-?

Really? Doing what?
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Postposted on Thu Jul 19, 2007 11:48 pm

I took a cursory glance over the article and it seems their only real complaint is that games in 32bit Vista will crash frequently, well, I have 2GB of memory and a Geforce 8800GTX 768MB, which is the hardware they were testing, and I don't have any games that crash, at least since Nvidia released that big driver fix back in March. Prior to that it was touch and go for a while.

But let it be said that for the past couple of months I've had a rock solid stable 32bit Vista system.
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Postposted on Fri Jul 20, 2007 12:08 am

Nitrodist wrote:Going to 64bit doesn't double it. If you went from 32bit to 33bit, that'd double it.

I assume you are replying to my post. Going to 64bit allows Windows to use the virtual address space beyond 4GB to do a lot of the stuff it would normally be forced to do between the 2GB and 4GB mark in 32bit windows. This frees up more of the virtual memory between the 2GB and 4GB for application use. Perhaps "doubling' is an exaggeration, but a 64bit OS should resolve the memory issue for someone playing a memory demanding 32bit game with a big memory GFX card like the 8800GLX. As I said, for 64bit games virtual memory is not an issue.
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Re: 8800GTX breaks 2GB memory barrier in vista?

Postposted on Fri Jul 20, 2007 12:10 am

Shinare wrote:I have Vista because its asinine to have a DX10 card and not have DX10.

By that logic, it would also be asinine to have a 64-bit capable CPU and not run a 64-bit OS and applications. (Never mind the fact that x86-64 capable CPUs are also excellent at running 32-bit OSes and code.)

At this point, what does DX10 really add to the end user experience? I'd say... not a whole lot, in the grand scheme of things. Give it another year or two, and maybe I'll start to consider DX10 a "must have" feature. Or maybe not (time will tell).
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Postposted on Fri Jul 20, 2007 12:21 am

It's worth noting that the WoW64 that exists in XP64 and Vista64 behave the same as 32bit Windows. Assigning 2GB of virtual space for the application.

If the 32bit application under WoW64 has the Large_Address_Aware, then 4GB of virtual address space becomes available to the application. In 32bit Windows the Large_Address_Aware limits to a maximum of 3GB to the application and 1GB to the system.

Large_Address_Aware is not without caveats even under WoW64. It should not be considered a fix.

http://blogs.msdn.com/slavao/archive/20 ... 50096.aspx
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Postposted on Fri Jul 20, 2007 12:35 am

If a game was written in such a way that address pointers above 2GB would cause problems, then it would not need more than 2GB of virtual address space. Otherwise, the bug would have been caught. If the unusually large memory of a GFX causes a problem in a badly written 32bit game, then the 32bit game should be patched by the developer.

In a 32bit game that was written to possibly use more than 2GB of virtual memory, Large_Address_Aware should not be a problem, and any bugs not caught in testing are very unfortunate and should be patched.

Large_Address_Aware is mainly a problem with older games that never foresaw the possibility that more than 2GB may be required. Large_Address_Aware is not required and should not be enabled for those games.
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Postposted on Wed Jul 25, 2007 8:23 am

I have read both articles. Basically if you Vista, go Vista 64, because Vista 32 has a problem where it eats your address space, nothing to do with installed memory this is the 2GB user address range. You will hit the same problem with 512mb or 4 G of memory installed. The problem is that Vista is mapping video memory into user space. The bigger your Video ram, the more address space you lose in Vista.

The results with CoH with different amounts of video card memory(on some resource intensive mission):

Vista:
256MB - 1.7G (Safe)
512MB - 1.9G ( on the edge)
768MB - 2.1G ( Potential Crash).

XP:
256MB - 1.3G ( Safe)
512MB - 1.3G ( Safe)
768MB - 1.3G ( Safe).

I say potential crash because they moved 2GB barrier (which can cause its own problmes) so it didn't actually crash. They actually did crash Supreme Commander this way even with the moved barrier.

As you can see XP doesn't map in your video ram, so you don't run out of address space. Vista does and you potentially run into problems on certain resource intensive games like SupCom and CoH.

While Vista 64 wasn't tested it likely does the same thing and Supreme Commander will crash just as quick as it is not Large Address aware, you need to hack the EXE to flag Large Address Aware, then it would be OK in Vista 64.

My thoughts, don't rush to Vista, if you must, go Vista 64.
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Postposted on Wed Jul 25, 2007 1:12 pm

snowdog wrote:I have read both articles. Basically if you Vista, go Vista 64, because Vista 32 has a problem where it eats your address space, nothing to do with installed memory this is the 2GB user address range. You will hit the same problem with 512mb or 4 G of memory installed. The problem is that Vista is mapping video memory into user space. The bigger your Video ram, the more address space you lose in Vista.

A game is unlikely to allocate more than 2GB of virtual address space if you have only 512MB physical memory. It would mean that you have almost 1.5GB swapped out to disk. Your biggest problem here is performance, as the computer struggles to swap memory pages in and out of disk storage. A game that manages to do this without degrading performance is probably suffering from a serious memory leak. If the system requirement for your game is 2GB, you would do well to invest in 2GB of physical memory. If you have 2GB, an 8800 GFX and a game that requires 2GB and it crashes, the Large_Address_Aware solution and 64bits should be considered.
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Postposted on Wed Jul 25, 2007 2:53 pm

murfn wrote:A game is unlikely to allocate more than 2GB of virtual address space if you have only 512MB physical memory. It would mean that you have almost 1.5GB swapped out to disk. Your biggest problem here is performance, as the computer struggles to swap memory pages in and out of disk storage. A game that manages to do this without degrading performance is probably suffering from a serious memory leak. If the system requirement for your game is 2GB, you would do well to invest in 2GB of physical memory. If you have 2GB, an 8800 GFX and a game that requires 2GB and it crashes, the Large_Address_Aware solution and 64bits should be considered.


You are mixing and matching unrelated issues here:

On the likelihood of allocation and installed memory, I disagree. I doubt most (if any) games check the physical memory and then decide how much to allocate. I am an experienced programmer (employed as software developer since early 1990's) and I have never seen a program of any complexity/size that didn't dynamically allocate memory on the fly as the situation changes by doing new on structures/objects as they are needed. There are no checks before hand on available physical memory. We live in a virtual world and address space is our memory limitation.

It is up to the user to improve his experience by adding more ram if he has too much swapping. While I agree that if your game is using 2GB of virtual memory, you would be wise to install 2GB of Physical memory to minimize swapping. This has nothing to do with the issue at hand.

The issue is Vista using over 2GB of address space for CoH while XP only uses 1.3GB. There is massive resource wastage happening in VISTA.

Insanely massive. We are not talking 5% or 10% extra here. We are talking 60% extra wasted with Vista.

Also note the GAME didn't require 2GB, it required 1.3GB (in XP), Vista burned about 800 MB and put it over the limit.

Now if Microsoft fixes Vista and you still blow the 2GB limit it is time to rag on the game developer, get Vista64 etc. But that is not the case. The only reason CoH is anywhere near the 2GB limit is because of Vista chowing down 800MB, or nearly half the available address range.
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Postposted on Wed Jul 25, 2007 3:56 pm

A 32bit process has 4GB of virtual address space. Of those, only the bottom 2GB are available for allocation (assuming no Large_Address_Aware). The system uses the top 2GB. The bulk of the virtual address space held by the video card would be in the top 2GB. If I understand it correctly, with the 8800GTS the top 2GB is not enough for the system, and hence a portion of the bottom 2GB is usurped by the system. A machine with 2GB of physical memory, running a game requiring 2GB of memory, would not be able to map the whole 2GB into the less than 2GB of available virtual address space.

If it had 1GB of memory and 1GB in swap space it would also have a problem mapping the sum into the smaller address space. But even if you succeeded in mapping 2GB of memory in such a machine, half your memory would be on disk, and the game would be virtually unplayable.

Therefore, the real problem is with machines that have the physical memory to fill 2GB worth of virtual address space, but cannot do it because the 8800GTX is eating a chunk of the bottom half of the virtual address space, and doing so on games that require 2GB of memory (not 1GB games).
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Postposted on Wed Jul 25, 2007 4:08 pm

You think it's bad with Vista mapping your 1*768MB 8800GTX? Try 7950GX2 at 2*512MB. Gord forbid, you could drop in two and vista would be snatching 4*512MB of address space away. When I ran Vista on quad SLI, even though it was Vista 64, I still had tons of apps crashing out with out-of-memory notes in the system log.


I suppose things will be better once we get to 4 or 8GB being standard, and most folks running Vista 64, but that day may be very, very far away.

In the mean time, XP64 is still the best option for the >2GB crowd.
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Postposted on Wed Jul 25, 2007 4:09 pm

murfn wrote:A 32bit process has 4GB of virtual address space. Of those, only the bottom 2GB are available for allocation (assuming no Large_Address_Aware). The system uses the top 2GB. The bulk of the virtual address space held by the video card would be in the top 2GB. If I understand it correctly, with the 8800GTS the top 2GB is not enough for the system, and hence a portion of the bottom 2GB is usurped by the system. A machine with 2GB of physical memory, running a game requiring 2GB of memory, would not be able to map the whole 2GB into the less than 2GB of available virtual address space.


Uh no. The top half is kernel space, there would be seriously no point mapping the VRam into kernal space.

The problem is VISTA is remapping the whole of the VRAM into the user space. XP doesnt do this, There is no need to do this, it is just done for DRM.

Note the size difference between Vista and XP memory usage. 800MB almost identical to the size of the VRAM on the video card.

And again. Physical memory is irrelevant to this problem and again the game is taking up 1.3GB on XP, 2+GB on Vista. Has this escaped your notice.

Why do you keep trying to defend Vista when it is chewing up all the address space?
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Postposted on Wed Jul 25, 2007 4:42 pm

Forge wrote:
In the mean time, XP64 is still the best option for the >2GB crowd.


It seems that in the meantime XP32 may be the best option for the <=2GB crowd. Either way I am happy to let others do the beta testing on Vista.

I am staying with XP until there is something I absolutely must run on Vista. So far nothing is even on the horizon.
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Postposted on Wed Jul 25, 2007 4:55 pm

The more I read about stuff like this, the more I'm convinced that my current gaming computer with an E6400 CPU, 2GB of RAM, 7950 GT and Windows XP might be my last gaming box. I think I will ride this system out for two or three years and then go the console route. Hopefully the successor to the Xbox 360 is out by then.
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Postposted on Wed Jul 25, 2007 11:11 pm

I hate to say it, but I'm starting to agree with that statement, even after just spending close to $1,400 on this computer.

I just watched the DX10 lovin in the beta World in Conflict earlier today and just finished playing some of the open beta. Looks really nice.

I've got Vista x64 and I guess I will wait and see if there are hacked EXEs for the games that I want to play that aren't already "aware". Now I just need to decide if I need to up my physical memory from 2GB to 4GB.
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Postposted on Thu Jul 26, 2007 12:30 am

snowdog wrote:Uh no. The top half is kernel space, there would be seriously no point mapping the VRam into kernal space.

Take a look at the tables on the first page of AnandTech's article at http://www.anandtech.com/showdoc.aspx?i=3044. The virtual address space at game start is consistently well below your VRAM size. Vista uses the GFX card in a different way to XP. The Aero interface is 3D, which means that the only limit on video memory used by the API is the whole VRAM. To ensure stability, Vista requires the ability to swap out video memory. To do this the video memory has to be mapped to virtual address space. And there is no reason why that cannot be above the 2GB mark.

snowdog wrote:The problem is VISTA is remapping the whole of the VRAM into the user space. XP doesnt do this, There is no need to do this, it is just done for DRM.

Where did you get this little gem from?

snowdog wrote:Note the size difference between Vista and XP memory usage. 800MB almost identical to the size of the VRAM on the video card.

I am not sure what your original numbers represent exactly.

snowdog wrote:And again. Physical memory is irrelevant to this problem and again the game is taking up 1.3GB on XP, 2+GB on Vista. Has this escaped your notice.

Code: Select all
user_virtual_address space = min(2GB,4GB - system_reserved_address_space)
if (physical_memory > user_virtual_address_space)
  max_usable_physical_memory = user_virtual_address_space
else
  max_usable_physical_memory = physical_memory


Why do you keep trying to defend Vista when it is chewing up all the address space?

I am explaining the issues to this forum. That is all.
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Postposted on Thu Jul 26, 2007 8:59 am

murfn wrote:
Why do you keep trying to defend Vista when it is chewing up all the address space?

I am explaining the issues to this forum. That is all.


I can only speak to my own understanding, but you made everything as clear as mud.

The core issue here is that Vista is chewing up all of the 2GB of system address space and continuing in on the user address space in many, possibly most configurations. This is a critically bad thing. Why it is doing it is tangential, the point that is being made, and that is so very upsetting, is that Vista is breaking something fundamental that worked in every other OS, and nobody has promoted a good explanation as to why.
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Postposted on Thu Jul 26, 2007 9:18 am

murfn wrote:Take a look at the tables on the first page of AnandTech's article at http://www.anandtech.com/showdoc.aspx?i=3044. The virtual address space at game start is consistently well below your VRAM size. Vista uses the GFX card in a different way to XP. The Aero interface is 3D, which means that the only limit on video memory used by the API is the whole VRAM. To ensure stability, Vista requires the ability to swap out video memory. To do this the video memory has to be mapped to virtual address space. And there is no reason why that cannot be above the 2GB mark.


I am reminded strongly of the phrase: "A little knowledge is a dangerous thing". Again you make extraneous connections that are completely unrelated to the issue at hand. Aero isn't involved in gaming. Aero has nothing to do with mapping Vram into user space. You can turn off Aero and it will have the same effect.

Mapping Video memory into the Kernel address space is indeed the problem. Yes there are big reasons why it can't be done above the 2GB mark.

The reason you map into user space is because this because your only way of accessing the graphics card. If you put it in Kernel space you LOSE that access. You don't have access to kernel memory.
Further to that it is clear They are not mapping it to kernel space.

snowdog wrote:The problem is VISTA is remapping the whole of the VRAM into the user space. XP doesnt do this, There is no need to do this, it is just done for DRM.
Where did you get this little gem from?


http://msdn2.microsoft.com/en-us/librar ... ctx_topic3
"Memory allocations are limited to the application address space primarily for security reasons. WDDM provides increased security by isolating applications and their resources from each other."

This is talking about the new video driver. Vram access is now in user address space primarily for "Security" reasons. That is to keep one application from peeking at the protected video streams, AKA DRM.


snowdog wrote:Note the size difference between Vista and XP memory usage. 800MB almost identical to the size of the VRAM on the video card.
I am not sure what your original numbers represent exactly.


Did you even read the articles the original poster linked?

Vista:
256MB - 1.7G ~400MB more than XP
512MB - 1.9G ~600MB more than XP
768MB - 2.1G ~800MB more than XP

XP:
256MB - 1.3G
512MB - 1.3G
768MB - 1.3G

It should be totally clear that Vista is burning Address space by remapping the video memory into to. None of it is going into Kernal. This might be a good idea in pure 64bit Vista, but in 32bit Vista this is a major issues that is chewing up the address space.


Code: Select all
user_virtual_address space = min(2GB,4GB - system_reserved_address_space)
if (physical_memory > user_virtual_address_space)
  max_usable_physical_memory = user_virtual_address_space
else
  max_usable_physical_memory = physical_memory



This pseudo code is an example of high school programming intro course thinking. So first of all where do you get these values? How do you determine how much of address spaces is going to be gobbled up by Vista vs XP? Even if you did get a handle on that number, what do you do next? Are you going to keep a running total of every "new" that you do, subtracting for every "delete". How are you going to account for static allocations, how are you going account for kernel allocations?

Even if you lived in some kind of fairy tale world where you could accurately track all of this, what do you do with it, when you see you are running out? You just stop the game? You are no farther ahead than merely checking return from "new" and finding out that you are out of memory.



Why do you keep trying to defend Vista when it is chewing up all the address space?
I am explaining the issues to this forum. That is all.


That might be fine if you actually knew what you are talking about.
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Postposted on Thu Jul 26, 2007 9:26 am

Forge wrote:
murfn wrote:
Why do you keep trying to defend Vista when it is chewing up all the address space?

I am explaining the issues to this forum. That is all.


I can only speak to my own understanding, but you made everything as clear as mud.

The core issue here is that Vista is chewing up all of the 2GB of system address space and continuing in on the user address space in many, possibly most configurations. This is a critically bad thing. Why it is doing it is tangential, the point that is being made, and that is so very upsetting, is that Vista is breaking something fundamental that worked in every other OS, and nobody has promoted a good explanation as to why.



Actually ignore him. He is completely incorrect about Vista using Kernel/system space and continuing into user space. The issue according to Microsoft own documents is that VRAM is now mapped into User address space for "security" reason. These are facts.

If you wish, ignore my interpretation that this "security" is DRM, because I agree with you, the reasons are largely tangential. They are doing it, their documents say they are, we can see the loss of address space, and we are stuck with the fallout. This is a major negative change from a user perspective because of the massive loss of resource (address space) that did not happen in XP, a lot more game crashes are happening as a result.

Avoid Vista32 like the plague, Use Vista64 with great care, you may need to make games Large Address aware just to get XP32 levels of address space.
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Postposted on Thu Jul 26, 2007 9:30 am

Forge wrote:The core issue here is that Vista is chewing up all of the 2GB of system address space and continuing in on the user address space in many, possibly most configurations. This is a critically bad thing. Why it is doing it is tangential, the point that is being made, and that is so very upsetting, is that Vista is breaking something fundamental that worked in every other OS, and nobody has promoted a good explanation as to why.


It's not that Vista is "using" the upper 2GBs of the 32-bit virtual address space, it's that the application doesn't know to use it. If the application is compiled with the large address aware switch, and doesn't play any games with pointers under the false assumption that virtual addresses above 2GB (or above 1GB) are invalid, then the application can use ALL 4GBs of 32bit virtual address space in Vista 64 bit.

The problem is that Vista evidentally throws the VRAM of the videocard into the userspace of the process. This means that there is less virtual address space available for the application itself. This, with only than 2GB total available to a non-large address space aware application, creates problems with a lot of newer games.
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Postposted on Thu Jul 26, 2007 9:41 am

snowdog wrote:This is talking about the new video driver. Vram access is now in user address space primarily for "Security" reasons. That is to keep one application from peeking at the protected video streams, AKA DRM.


That's undoubtedly a very important reason, but it's certainly not the only reason. The virtualization of videocard memory in userspace is generally just a good idea. Aero wouldn't be able to play well, if at all, with windowed 3d programs, if this aspect (and others) of WDDM didn't exist.
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