The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

LinWinOverlord — Sun, 02 Apr 2006 18:20:03 GMT

Wow, this is very interesting, it also explains why it is necessary to have a different model, especially with Windows Presentation Foundation being implemented over as DX10 surfaces..

DWM и WDDM — близнецы или однофамильцы? [Грег Сшечтер]

Олег Михайлик — Sun, 02 Apr 2006 20:11:38 GMT

Ленин и Партия будущей версии Microsoft Windows — Оконный менеджер рабочего стол

Understanding WDDM and DWM

Robert McLaws: FunWithCoding.NET - Longhorn Edition — Sun, 02 Apr 2006 22:25:19 GMT

Greg Schechter&nbsp;has an interesting write-up on the Role of WDDM in the Desktop Window Manager.

re: The role of the Windows Display Driver Model in the DWM

Piethein Strengholt — Mon, 03 Apr 2006 14:26:11 GMT

Could you tell us what we've seen so far? What is used in 5308 and 5342? The flip 3d doesn't look very nice.. No Anti Aliasing and the preview tumbnails they look a bit blurry. Do you have plans to improve this? And what's next?

re: The role of the Windows Display Driver Model in the DWM

Raiker — Mon, 03 Apr 2006 17:22:29 GMT

Олег Михайлик, ура, ура, ура! Партия и родина тебя на забудет! А про DWM надо читать на TheVista.ru ;-)

Greg Schechter, thanks for this article, very nice story.

EXCP. 06/04/04

息乐园 — Mon, 03 Apr 2006 19:10:15 GMT

<ul><li> <a href="http://blogs.msdn.com/greg_schechter/archive/2006/04/02/566767.aspx" target="_blank">The role of the Windows Display Driver Model in the DWM</a><br/></li></ul>

re: The role of the Windows Display Driver Model in the DWM

Jerry Mead — Mon, 03 Apr 2006 21:27:02 GMT

Interesting piece, many thanks. I'd love to have been present at the early "Is this actually do-able" meetings.

re: The role of the Windows Display Driver Model in the DWM

Stephane Rodriguez — Tue, 04 Apr 2006 14:19:32 GMT

It seems to me there is at least one more challenge not being addressed above : GPU heat. What about Vista DWM on laptops, Tablet PC and other form factors? What about a combined multi-core board with DWM in terms of heat?

Understanding WDDM in the Desktop Window Manager » Windows Vista Connected

Understanding WDDM in the Desktop Window Manager » Windows Vista Connected — Wed, 05 Apr 2006 09:01:03 GMT

PingBack from http://pcwinvista.com/understanding-wddm-in-the-desktop-window-manager-5.html

re: The role of the Windows Display Driver Model in the DWM

Sherrod Segraves — Wed, 05 Apr 2006 18:28:46 GMT

How does this work with multiple monitors, or even multiple video cards?

If I want the full UI experience with three or four monitors, would I need to look for a quadruple-head video card, or could I use two dual-head cards?

re: The role of the Windows Display Driver Model in the DWM

asdf — Thu, 06 Apr 2006 01:45:58 GMT

What do you mean by "there are effectively no more "surface lost" messages from DirectX"? "effectively" in that sentence looks to me like there are surface lost messages but it only occurs because you allow applications to allocate more memory than can actually be committed somewhere. I hope I am wrong and there is none of this behavior at all.

Ungrounded Outlet » Blog Archive » Xtreme Card Flipping

Ungrounded Outlet » Blog Archive » Xtreme Card Flipping — Thu, 06 Apr 2006 02:05:29 GMT

PingBack from http://ungroundedoutlet.com/blog/?p=28

re: The role of the Windows Display Driver Model in the DWM

Aleko — Thu, 06 Apr 2006 04:09:56 GMT

So, the WDDM would allocate a buffer for each window. Sounds simple, but how much memory to allocate? When the window is resized, the requirements would change, and it reallocating the buffer on the fly would be absurd. So... allocate enough space for a fullscreen-sized buffer?

If so, then:
1 window @ 1280x104 x 32bpp = 5.2MB
10 windows = 52MB!

This can't be right.

re: The role of the Windows Display Driver Model in the DWM

Frederik Slijkerman — Thu, 06 Apr 2006 10:11:17 GMT

It is right... that's why MS didn't try this in the days of 8 MB RAM - Windows 95.

re: The role of the Windows Display Driver Model in the DWM

Princess — Thu, 06 Apr 2006 10:16:41 GMT

Aleko: 52MB? It far worse than you think :-)

Background apps don't receive WM_PAINT messages when they are revealed by a window moving above them. This necessitates that the window contents is buffered. For this to buffer to be always available, the application can't render directly to it or you would see incomplete rendering. So each window needs to have 2 buffers - one for rendering, one for the DWM to access. Unless something sneaky is going on involving serialisation of rendering... Greg?

Resizing is an interesting question though. Does Vista allow the window contents to be shown when resizing? Because that sounds hard to do without frequent reallocations or fullscreen buffers. I guess you could fake it by performing an imaging operation to scale the original backbuffer onto the on-screen location whilst resizing. Then you could properly redraw the window using its new size after the resizing drag is completed. That way you only need to reallocate the backbuffer once.

re: The role of the Windows Display Driver Model in the DWM

Michael — Thu, 06 Apr 2006 17:06:12 GMT

Eh... the memory is to be expected. If you want the next generation of apps, get the next generation of hardware.

re: The role of the Windows Display Driver Model in the DWM

Jevan — Thu, 06 Apr 2006 17:55:43 GMT

Piethein -- we're actively working on improving the visual quality of Flip3D and thumbnails. Unfortunately whereas games have the luxury of turning on all sorts of visual quality knobs like multisampled edge antialiasing, mipmapping and anisotropic filtering, each one of these features comes at a significant cost. Being the DWM we have to coexist with all the other apps on the desktop, which means we need to be very careful about constraining our CPU and GPU resources (both runtime and memory usage) and we can't afford enabling these features. Greg (or I) can delve into more details in a later blog post.

Aleko -- yes, you're right. A fullscreen window at 1280x1024 takes up 5MB. When you consider that modern video cards currently only have 128MB or 256MB of memory, it is obvious why WDDM's virtualization model is so important. We need to be allow these surfaces to be paged out from video memory to system memory to make room for other windows' surfaces or other DX apps' GPU resources.

Princess -- Greg will be covering this in later planned posts, but I can briefly answer now. You are correct that we need two surfaces, but not because of any locking/synchronization problems (we can read from a surface as an app is writing to it if we want). It is because the GPU can only render from surfaces visible to it, which means the surface has to reside either in video memory or in "non-local video memory" (aperture space). Due to a number of constraints we create the GDI sprite wherever we want in system memory and then transfer it to GPU-visible memory when necessary.

re: The role of the Windows Display Driver Model in the DWM

Tom Kirby-Green — Sun, 09 Apr 2006 01:08:14 GMT

I'm really enjoying this series of articles. No one else seems to be covering this in such detail so your blog is a unique goldmine of Avalon goodness. Thank you and keep up the great posting!

re: The role of the Windows Display Driver Model in the DWM

Lorenzo — Mon, 10 Apr 2006 10:23:49 GMT

Like Stephane Rodriguez points out: what about Laptops? Battery life and heat? Using the GPU when on battery brings my laptop battery life from 3.30 hrs to 1.30...

Desktop Window Manager Index of Post Topics

Greg Schechter's Blog — Fri, 21 Apr 2006 10:06:01 GMT

Here's a list of topics that I have posted on (with active links) or expect to post on (without links)...

re: The role of the Windows Display Driver Model in the DWM

igor1960 — Mon, 01 May 2006 22:35:37 GMT

While WDDM idea is interesting from User Experience as well as development aspects, I feel it introduces conflicting aspect into Windows development.
Before, WDDM each Window on receiving WM_PAIN message and/or otherwise through its own DC was responsible for drawing its own content on its own surface. Therefore, as each Window belongs to separate process, developed by different developers, such process was “responsible” for proper rendering of that drawing content and therefore it could be optimized/debugged and etc. independently from other UI component running on the desktop.

Now, with WDDM extra layer is introduced, and now effectively above described Window painting are performed into WDDM supplied bitmap buffers, managed by WDDM and as the result those buffers are transferred by WDDM to Desktop.

This WDDM extra layer maybe seen as an advantage as it allow to produce “visual effects”, as WDDM at any moment in time maintains all content of all windows running on the system.

However, alternatively it maybe seen as an extra not efficient burden on the system, as it introduces one extra memory and processor power hungry element into the system.
I could point to several scenarios when the system utilizing WDDM will obviously “suffer” compared to standard XP performance wise (for example, now each window has to respond to WM_PAINT message and redraw it’s full content, even if it is not visible at all), but I will decide to limit myself to the following scenario. Let’s assume:
-- I have currently DirectShow application A that is playing some content with 30fps refresh rate on standard XP system (no WDDM);
-- I have 60Hz Adapter/Monitor system;
-- I have just enough processing power on XP system to run 2 applications A on my system simultaneously;
-- as I have 60Hz Adapter/Monitor system and I’m running 2 applications A each updating Monitor with 30fps – my system perfectly displays content of both applications to the user;
Now let’s examine that scenario on WDDM system:
-- I have the same DirectShow application A that is playing some content with 30fps refresh rate on standard (on WDDM);
-- I have 60Hz Adapter/Monitor system;
-- I do not have enough processing power on WDDM system to run 2 applications A on my system simultaneously, because now each of those applications pass there content to WDDM that require extra processing power to combine and render content from 2 applications;
-- as I have 60Hz Adapter/Monitor system and I’m running 2 applications A each updating Monitor with less then 30fps – my system skips some frames.

Conclusion: while User Experience is very important, the first requirement from OS is to provide the most efficient and fastest way to deliver content and if such delivery suffers in order to achieve some “visual effects”, efficiency aspect should prevail and system should allow to turn off those effects. Therefore, Vista, while providing WDDM as default for users not concerned with speed of execution, should also provide option to turn WDDM completely off (XP compatible mode) and it would be nice to do that not just on OS level, but per application and possibly module/call.

Redirecting GDI, DirectX, and WPF applications

Greg Schechter's Blog — Wed, 03 May 2006 08:32:07 GMT

As mentioned in earlier posts, by far the most important aspect of the DWM is the fact that application...

Wiosennie: Ciekawe zastosowanie dla WDDM?

Co Kierepka czyta, wie lub myśli, że wie :) — Wed, 03 May 2006 13:42:18 GMT

Windows Display Driver Model – z tego co rozumiem, ma on możliwość współdzielenia obszaru pamięci DirectX...

Avalon Hardware Acceleration & Video Driver Compat

avalite — Tue, 06 Jun 2006 03:52:40 GMT

Hello. Seema Ramchandani here, PM of the Avalon 2d &amp; 3D graphics team.
&nbsp;
Many people have...

DWM &amp; Aero Glass at work

David Boschmans Weblog — Thu, 08 Jun 2006 14:01:42 GMT

When talking about WPF during the Windows Vista ISV Touchdown training a lot of people were interested...

WPF Graphics Performance Q & A - Some explanations about WPF graphics architecture & overhead

Tim Cahill - the WPF Perf Guy. WPF Graphics ala carte. — Sat, 17 Jun 2006 01:12:15 GMT

&nbsp;
I’ve been getting a lot of the same performance questions over the last few months regarding...

Avalon Hardware Acceleration & Video Driver Compat

SilverLite — Tue, 20 Nov 2007 05:41:01 GMT

Hello. Seema Ramchandani here, PM of the Avalon 2d & 3D graphics team. Many people have asked me

ms windows display is too large

ms windows display is too large — Sat, 31 May 2008 15:54:48 GMT

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The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

DWM и WDDM — близнецы или однофамильцы? [Грег Сшечтер]

Understanding WDDM and DWM

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

EXCP. 06/04/04

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

Understanding WDDM in the Desktop Window Manager » Windows Vista Connected

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

Ungrounded Outlet » Blog Archive » Xtreme Card Flipping

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

re: The role of the Windows Display Driver Model in the DWM

Desktop Window Manager Index of Post Topics

re: The role of the Windows Display Driver Model in the DWM

Redirecting GDI, DirectX, and WPF applications

Wiosennie: Ciekawe zastosowanie dla WDDM?

Avalon Hardware Acceleration &amp; Video Driver Compat

DWM &amp;amp; Aero Glass at work

WPF Graphics Performance Q &amp; A - Some explanations about WPF graphics architecture &amp; overhead

Avalon Hardware Acceleration & Video Driver Compat

ms windows display is too large

Freecell | keyongtech

Greg Schechter s Blog The role of the Windows Display Driver Model in | storage bench

Avalon Hardware Acceleration & Video Driver Compat

DWM & Aero Glass at work

WPF Graphics Performance Q & A - Some explanations about WPF graphics architecture & overhead