castanyes blaves

Random ramblings about some random stuff, and things; but more stuff than things -- all in a mesmerizing and kaleidoscopic soapbox-like flow of words.



Linux versus Mac vs Windows graphics

Slashdot | Linux 2.6.28 Promises Year-End Presents
Maybe I'm misunderstanding your assertion, but hasn't MacOS X had universal GPU RAM management for many years? I don't think MS has any monopoly on this... it was my impression that it was just Linux that was on Microsoft's heels playing catch-up.

Yes you are misunderstanding, and NO the Mac has not...

OS X uses the 3D GPU as a bitmap composer for the display, and that is it.

OS X's composer is years behind most Linux desktop composers as well as Vista's DWM/Aero. Vista's DWM for example is Vector/Bitmap based, and works with the WDDM of Vista that gives it a lot of power. (WDDM is the new driver model in Vista)

Here are some of the things Apple needs to add to catch up to even Vista.

- GPU RAM Virtualization/sharing (something kind of like what they are trying do with the Intel chipsets and Linux in this article - except Vista does this over the AGP/PCI bus with any Video card and works with or without dedicated GPU VRAM.

- GPU Scheduler - In Vista, the OS, not the applications controls the GPU, and Vista brings pre-emptive multi-tasking to the GPU. (And no this is not like OpenGL applicaiton yielding/cooperative multitasking, as DirectX also does what OpenGL does. This is an OS level management system that opens up a new way of thinking beyond one 3D application on screen at a time concepts that don't depend on applications yielding the GPU. Kind of like the move to the 32bit era where the Intel CPUs offered a pre-emptive scheduler.

(Example: several games on screen at once in Vista, set transparent with a HD video waterfall playing in the background and losing very few FPS in each game and Aero also using the 3D GPU to do its things, like compose the Game Windows with a transparent waterfall behind them and do a shared texture combine write to the video card.) - This is not something you want to try on a Geforce 5200, but it will work, and on newer video cards, even the 7900 series from Geforce, you can do some really amazing things when running multiple games 'viewable' on the screen at once.

- Legacy application 3D acceleration. Apple tried to get this going with 10.4 as an optional switch, but it was too buggy and scrapped as a feature for 10.5. This means that OS X still renders content using good old fashion legacy 2D GPU features or SSE Intel extensions. On Vista, even Windows 3.1 applications get a performance boost as GDI drawing, Font Rendering, and even internal bitmap APIs are shoved through the 3D GPU because it is significantly faster than older 2D GPU rendering methods.

- Vector composer. On Vista when it is running newer WPF applications, instead of the DWM getting a bitmap that is composed to the final render of the screen, the WPF applications tell the DWM/Aero what changes are made, usually vector based (XAML), and the Vista composer makes the changes at the composer level instead of the application having to redraw the application and send a new bitmap of the Window to the composer to assemble. (This is also why RDP (Remote Desktop) on Vista is faster and more featured than XP, as it works at the DWM level and a lot of the operations sent over the network to render the screen are vector based and lightweight, leaving the client to do the heavy rendering instead of passing bitmaps all the time. This is why you can do Aero Glass and WPF 3D over a slow RDP connection remotely.

Ok, I am going to stop here, as I am writing this off the top of my head and it would better if you would just visit technet at and lookup the Vista WDDM and DWM and WPF technologies.

The whole driver and video changes in Vista were dramatic and borrowed ideas from the XBox 360 development team and do some really impressive things, even though MS didn't put much into the 'cute' uses of it in the UI like they are doing with Windows7.


Linux/*nix also has some good composer technologies that make OS X's composer pretty sad in comparison.

With Linux there are still some major driver and kernel level hurdles

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