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Video Memory Virtualization - A Brief Guide
stormy13
Published by stormy13
04 Jun 2010
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 Published by |
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This is a brief guide on how graphics memory works and is reported in Windows 7. There has been much confusion here and elsewhere with this due to how things are worded when looking at the detailed report from a WEI score for example,
Looking at the numbers above it would appear that there is a total of 2303 MB of video memory, however that isn't the case. To break it down and make it easier to understand you need to realize what the three variables listed are,
Dedicated graphics memory
This is the actual amount of physical memory that the video card will have, whether it is onboard or a dedicated video card. For most onboard video this value is what is allocated in the bios and deducted from the total of the system ram, and cannot be changed from within Windows. For a dedicated card this is physical ram on the card and cannot be upgraded like system ram can.
Dedicated system memory
This is mainly seen on Intel graphics solutions as seen here,
Another thing with the current generations of Intel graphics is that the amount of graphics memory is dynamic, meaning that the graphics run on the base amount as shown above but will increase as needed (and also lower the amount of available system ram at the same time).
Shared system memory
This is the number that throws a lot of people off. It is more like a pagefile for the video card, also known as "Virtualized video memory",
Windows Display Driver Model - Wikipedia, the free encyclopedia
and is a total of graphics memory and total system ram. What it doesn't do is take anything from system memory unless the full amount of graphics memory has been used, and then will only use what is required and release it once it is no longer needed.
This is what Microsoft has to say about it,
Graphics Memory Reporting through WDDM
Quote:
The new Microsoft Windows Vista Display Driver Model (WDDM) brings fundamental changes to the management of graphics memory in a system.
Prior to Windows Vista, graphics memory was reported by the graphics driver as a single number through the Display applet in the control panel. Some legacy APIs exposed two types of memory: local and non-local. However, these numbers were selected by the driver and were mostly inaccurate.
With the introduction of Windows Vista, the operating system is putting a much heavier load on the GPU than ever before. Overall system performance is now closely associated with the graphics subsystem performance and is directly affected by the amount of graphics memory available. Microsoft is enhancing how graphics memory is reported, so that end users can better understand the factors that directly impact the system performance. With WDDM, Windows Vista can accurately account for each of the graphics memory contributors and report available memory precisely through new APIs.
It's important for software running on Windows Vista to be able to accurately determine the amount of available graphics memory. WDDM manages the virtualization of graphics memory in itself and also ensures accurate reporting of various aspects of graphics memory. Application developers and software vendors are encouraged to take advantage of the DirectX 10 API for retrieving the accurate set of graphics memory values on systems that have WDDM drivers.
There is also a white paper on the above link for those interested in exactly how this number is determined. There is more about the changes made to how video memory works in Windows 7 here,
Engineering Windows 7 Graphics Performance - Engineering Windows 7 - Site Home - MSDN Blogs
Hopefully this will help clear up some of the confusion some have when looking at those numbers when they look at their WEI results.
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04 Jun 2010
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#1
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great explanation. Thumbs up 
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My System Specs |
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OS window's 7
CPU core 2 quad
Motherboard gigabyte
Memory 2gb corsair
Graphics Card ati hd4850
Monitor(s) Displays lg
Screen Resolution 1600 X 900
Case power logic
Other Info none of the spec above is accurate
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04 Jun 2010
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#2
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Very well done, Stormy. I have little knowledge of graphics cards and I followed this and learned.
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| My System Specs |
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System Manufacturer/Model Number Home built
OS Windows 7 Ultimate 32 bit
CPU Intel(R) Pentium(R) 4 CPU 3.00GHz
Motherboard ASUS P4P800-VM Motherboard Chipset: Intel 865G + ICH5
Memory 2.50 GB RAM
Graphics Card NVIDIA GeForce 7600 GS
Sound Card SoundMax Integrated Digital Audio (Chip)
Monitor(s) Displays ViewSonic VX 1962 wm
Screen Resolution 1680 X 1050
Keyboard Microsoft Comfort Curve Keyboard 2000 v10 USB
Mouse Logitec optic USB
Cooling Fan based
Hard Drives Seagate Barracuda 7200.10 80 GB
ST380215A ATA Device 18.6 GB
Western Digital "My Book" external hard drive 750 GB
Internet Speed 3.01 Mb/s download 0.64 Mb/s upload
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04 Jun 2010
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#3
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Nice one, Stormy. Tried to rep you but must spread around first 
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| My System Specs |
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Computer type Laptop
System Manufacturer/Model Number HP ENVY 17-1150eg
OS Windows 10 Pro x64 EN-GB
CPU 1.6 GHz Intel Core i7-720QM Processor
Memory 6 GB
Graphics Card ATI Mobility Radeon HD 5850 Graphics
Sound Card Beats sound system with integrated subwoofer
Monitor(s) Displays 17" laptop display, 22" LED and 32" Full HD TV through HDMI
Screen Resolution 1600*900 (1), 1920*1080 (2&3)
Keyboard Logitech diNovo Media Desktop Laser (bluetooth)
Mouse Logitech Performance Mouse MX
Cooling As Envy runs a bit warm, I have it on a Cooler Master pad
Hard Drives Internal: 2 x 500 GB SATA Hard Disk Drive 7200 rpm
External: 2TB for backups, 3TB USB3 network drive for media
Internet Speed 50/10 Mbps VDSL
Antivirus Windows Defender 4.3.9431.0
Browser Maxthon 3.5.2., IE11
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22 Jun 2010
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#4
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Nice explanation, this will be useful to refer people to, Thanks.
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| My System Specs |
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Computer type PC/Desktop
System Manufacturer/Model Number 76~2.0
OS Windows 7 Ult x64 - SP1/ Windows 8 Pro x64
CPU Intel Core i5-3570K 4.6GHz
Motherboard Gigabyte GA-Z77X UD3H, f18
Memory 8GB (2X4GB) DDR3 1600 Corsair Vengeance CL8 1.5v
Graphics Card Sapphire HD 7770 Vapor-X OC 1GB DDR5
Sound Card Onboard VIA VT2021
Monitor(s) Displays 22" LCD Dell
Screen Resolution 1680x1050
Keyboard Logitech Wave
Mouse CM Sentinel
PSU Corsair HX650W
Case Cooler Master Storm Scout
Cooling Corsair H80 2x12cm Noctua NF P12 , 2x14cm case fans
Hard Drives Samsung 840Pro 128GB SSD,
Seagate Barracuda 500GB SATA2 7200rpm 32MB cache, Seagate Barracuda 1TB SATA2 7200rpm 32MB cache,
Internet Speed Dismal
Antivirus Avast
Browser Opera Next
Other Info Haswell laptop: HP Envy 17t-j, i7-4700MQ, GeForce 740M 2GB DDR3, 17.3" Full HD 1920x1080, 16GB RAM, Samsung 840 Pro 128GB, 1TB Hitachi 7200 HDD,
Desktop: eSATA ports,
External eSATA Seagate 500GB SATA2 7200rpm,
External WD USB 500GB
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28 Aug 2010
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#5
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thank you stormy i'm gonna add to your reputation,
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| My System Specs |
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OS Windows 7 Home Premium 64-bit
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02 Nov 2011
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#7
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Quote:
Shared system memory
This is the number that throws a lot of people off. It is more like a pagefile for the video card, also known as "Virtualized video memory",
and is a total of graphics memory and total system ram.
this is not true,
Shared system memory is Virtualized video memory taken only from system ram ........
Dedicated graphics memory - 512mb - real memory on your video card
Shared system memory - 1791mb - additional memory taken (wiil be taken if necessery) from system ram
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Total available graphics memory: 512 + 1791 = 2303mb
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| My System Specs |
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