Windows 7 DWM cuts memory consumption by 50%


If you didn’t think the performance benefits of using Aero Glass could get any better, then see this. At PDC 2008, Anantha Kancherla presented a session on “Windows 7: Writing Your Application to Shine on Modern Graphics Hardware” where he presented a mindblowing fact about the Windows 7 Desktop Window Manager.

Because Windows 7 can take better advantage of the GPU and uses the Direct3D 10.1 API, it is able to reduce reduce memory consumption (in the graphics system) by 50% per each window rendered. On top of that, this is also what enables the much richer animation and styling of the interface like the “color hot-track” feature. Pretty cool huh.

61 insightful thoughts

  1. The DWM in Vista has always been a hog. Although I’m sure glass has always been done in shaders, I mean what was the point of requireing shader model 3.0 if they didn’t need it?

    50% memory reduction .. hmm.. I wonder if that’s gfx memory or main memory: Perhaps they had to have a copy in both and now they don;t… Could be something else like changing the pixel format or onchip compression or something though.

    I can’t belive they would require new hardware – that’s what it looks like from the slide “directx3d10.1” – if they want any hope of people upgrading from Vista at least.

    I mean look at what the people on the Linux side are doing graphics and programmability wise with soo much less, running full effects on 10 year old integrated graphics. And if you think vista has driver problems, try getting a nVidia accelerated gfx on linux!

    That’s enough ranting from me.

    Just give us good performance and an API damn it!

  2. I though that Windows 7 would be using D3D (DirectX) 11… or is that coming with the Windows 8?
    Thanks for all the really good updates! 😀

  3. Oh and thanks for all the coverage! Just wish I had enough bandwidth (and time!) to extract the actual interesting bits from all the vids myself.

  4. Spike no that isnt the case only ATI has so far released DX10.1 GPU’s, NVIDIA refused to do so though the fact that Windows 7 should perform better with ATI GPU’s may mean they suddenly have a change of heart (knowing NVIDIA they will probably try and bolt on 10.1 support to their DX11 GPU line).

    I’m guessing it works like this for Windows 7;
    Direct-X 9 minimum for Aero glass
    Direct-X10.1 for Aero Glass & better performance of the GUI.

  5. That’s great news. This might actually mean I can use Aero in Win7 on my Portege M200.
    It has an NVIDIA GeForce Go5200 with 32MB RAM. It can run Aero in Vista but runs out of vid memory after I open a few windows 🙂

  6. @Vank:
    Any DX10 card will run DX10.1, but it won’t be able to use the new features of DX10.1.
    Also, I doubt they used DX10.1 specific functions for DWM. Using the API doesn’t mean it uses the new DX10.1 funtions. 🙂

  7. Hopefully it will run GREAT on DX9c cards with 128Mb video ram (in other words, vista Premium ready).

  8. You know… it doesn’t matter how many upgrades Windows will do, I’d never go back to it I’m sick of this system.

  9. I simply refuse to believe this. EVERY SINGLE Windows release was promised to be faster than before, and MS failed this EVERY SINGLE time. There is just no way an OS from 2010 to have smaller RAM footprint than 2006 OS. I will believe when I see it.

  10. I think it’s likely Win7’s RAM footprint won’t grow much from Vista, and that is a win. As lame as it sounds, hardware has caught up with Vista’s bloated requirements, and if Win7 can do more in that same footprint then that’s a good thing. Maybe, just maybe, Microsoft realized how badly it screwed up with netbooks, UMPC’s, tablets, and other small footprint PC’s. If Win7 is indeed modular enough to create light-footprint editions, then there’s hope yet.

    Vista is utter crap for the consumer, and I’ve moved on to a Mac which has been an incredibly peaceful experience (despite the cost). But if MS can shed more light on Win7 being more responsive in every respect, I might just be intrigued enough to switch back.

  11. @Jiri Fiala

    Not quite true. Windows 98 to 2000 Pro. A nice speed boost was taken all around if you had all the right drivers. At the time I still think Windows 2000 Pro is still the best Win yet.

    All these news about Hardware support being better but what of PMP (protected Media Path) ?

    I don’t mind the DRM if it works acctually, but this has completely ruined Vista for me, talking from a memory load standpoint and the freak cracling when loading anything from IE. Pmp + DRM + Vistal killed my Audio Experience and hardware accell to my S.Blaster XI-FI

  12. @Matt Sharpe: I had the same thought. It’d be great to run Win 7 on the m200.

    I think the m200 is still one of the better (maybe not the best) tablet PCs that have been produced. You can’t beat 1400×1050 on a 12.1″ screen!

  13. All DirectX versions requires you to support all previous versions of DirectX, for example DX9 required PS1.4 support, DX10 required DX9 support etc. Thats why Nvidia Geforce GPUs after Geforce 4 Ti supported PS1.4 natively. DX11 will require DX10 and 10.1 support, it’s not simply bolted on. Microsoft’s decisions is pretty strange considering there’s plenty of ATI GPUs (HD2xxx series) and IGP chipsets that doesn’t even support DX10.1(780G, 790GX) so they’ll get zero benefits unless there’s proper fallbacks for DX10 hardware.

    Nvidia’s DX11 hardware will support DX10.1 natively and again, even Microsoft says DX10.1 is a minor update and very little games even supports DX10.1(why would anyone exclude all the DX10 hardware including the ATI ones I mentioned is beyond me) and with DX11 hardware coming soon, making it rather irrelevant.

  14. With Win7 you need a DirectX10 graphics card with at least 256MB to take advantage of -50% RAM memory consumation.

  15. which means requirements=DirectX 10 capable card? Or does it fallback to DX9.0c? Can you find this one out?

  16. @theoriginalsomeone
    with a Directx9 graphics card you’ll have the same performances of Vista
    with a DirectX10 graphics card you’ll save -50% of Mem/window

  17. Actually, I’m running 6801 on a PC that could barely run Vista(P4 2.0ghz, 1gb ddr ram, DirectX 9 128 DDR vram) and I don’t believe that the decrease in graphics memory being used is because of DirectX 10.1. I think they have overall improved the way that DWM works. I can play back HD videos on Windows 7 perfectly that I couldn’t play on Vista at all.

    I’m assuming that since only half my vram was used it was able to use the rest to play back the HD video correctly. How else can you explain me being able to play a file that I couldn’t playback smoothly even when WMP was the only thing open on Vista and now when I’m running a program that’s already using up 98% of my CPU power I can fire up WMP and play an HD video with just the video card?

    I’m thinking that unless the superbar uses up 64mbs of vram, Windows 7 will only need 64mbs of vram.

  18. I think Windows XP will be the last version I’ll invest in.

    * Jumps off Microsoft boat. Inflates a life raft. Starts paddling to alternatives. *

    As for Fowl’s (1st poster) comment about installing Nvidia drivers on Linux; I had no trouble with TNT2-M64, GF2 MX400, GF FX5200, GF4 ti4200, GF FX5900XT, GF7300GT, and GF7600GS. All worked without issue. Driver was installed in a few clicks. Linux’s desktop eyecandy works with a Geforce 1. (I tried with TNT2, didn’t do well. Need at least a Geforce 1 or better.)

  19. @Mark
    I don’t think decoding HD video has anything to do with vram, it’s probably just the inbox codecs are more efficient. AFAIK no dx9 card has hd video acceleration.
    As I was saying, it’s amazing how much they do with so little hardware. (or conversely, how little MS do with so much).

  20. A DX10 video card with Windows 7 drivers is needed to get 50% memory reduction per top level window. The saved memory is physical system memory.

    Video playback with DWM ON is improved by removing unnecessary memory copy to the DWM window surface.

  21. @ Olga, DX10.1 is required for the smaller memory footprint, not 10.

    @ Fowl, Aero requires SM2.0, not 3.0.

  22. windows 7 is only recognizxing 2gig
    I have vista on the same comp separated hardrive & it recognizez the 4 gig i have installed
    so i wondered why 7 only rcognizez the 2 gig

  23. I can’t believe this even made the news.

    XP looks fine. Patch the UXtheme file, use any theme you want.

    Why do we care of W7 can look like a supermodel while doing things slower than XP?

    Just my 2 cents worth!

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