[Mark Tungston]

Will a faster graphics card cause improved QE performance?

What is the real world improvement over a monster ATI9700 over a basic card that will support QE?

How much of what is on the screen is QE/GPU and how much is regular CPU?

Will Apple continue to move more computation/rendering to the cards in the future since modern graphics cards are so advanced?

What is the future of QE, can it be improved?

How would QE work with the ibm 970 (if apple went with it)?


Thanks, i don't know too much about it and i don't trust what's on Apple's website.

[Rickster]

Will a faster graphics card cause improved QE performance?

Yes, but...

What is the real world improvement over a monster ATI9700 over a basic card that will support QE?

It's hard to measure, and the real-world value depends almost as much on your own workload and your own perceptions of speed as on the technology.

It looks like the most important hardware factors for Quartz Extreme are fill rate, VRAM size and speed, and AGP bus transfer speed. So a lot of the areas in which GPU hardware is improving don't mean much to QE performance -- 3D transform & lighting, vertex shaders, bump mapping and the like don't have an impact because they aren't used.

Since some of those hardware factors are part of your machine, not just part of the card, video card upgrades might not give you as much bang as you might expect. (If you replace the original AGP Radeon in an old G4 with a 9700, you may not perceive a great improvement in your GUI performance, since you're still on a slow system bus.)

How much of what is on the screen is QE/GPU and how much is regular CPU?

Less than people tend to think.

The CPU, at the direction of individual applications, is responsible for drawing the contents of windows. (Note also this means more than just the things with title bars. Hit Cmd-Shift-4 then Space and drag around the screen, and you'll see highlighted all the things that are separate "windows" as far as the OS is concerned: the menu bar, each icon on the dock, and more.) Every icon, every letter, every color fill, and every widget in the window you're looking at right now are drawn via the CPU into a buffer in main memory.

Before QuartzExtreme, the CPU also was responsible for compositing all those window buffers into the single screen image you see -- handling all the blending of translucent windows and window parts, drop shadows, etc. The only times the GPU would be used were when you were playing video or running an app that used OpenGL (typically to draw 3D scenes), and in those cases, the GPU was only responsible for drawing a particular area: the movie frame or the window containing 3D content. (Unless, of course, you were playing video/3D fullscreen.) That rather limited interface to the GPU didn't allow for such things as window compositing, so you'd end up with strange effects and/or reduced performance whenever something put a translucent overlay over the hardware-accelerated content.

Now, the Window Server renders the screen as a pseudo-3D scene using OpenGL hardware acceleration. 3D hardware has become very good at moving large 2D textures around and blending partial pixels together, so we're able to leverage that in compositing all the window buffers into a single screen image as mentioned before. (We're also able to use Direct Memory Access features available in supported hardware to take additional load off the CPU by having the GPU "pull" data out of main memory instead of requiring the CPU to "push" data to it.) And since the GPU is now responsible for the entire contents of the screen, it's now possible for it to better integrate the 2D windowing system with other types of hardware-accelerated graphics (video and 3D). The immediate benefits of all this is that window-system tasks are a heck of a lot faster than otherwise: translucent drop-down menus open and close faster, windows drag more smoothly, and you can have the volume/brightness overlays on top of DVDs without getting reduced framerates or weird graphical artifacts. In the long term, we may see interfaces that integrate 2D, 3D, and video content in ways we haven't even though of.

This necessary separation between CPU and GPU tasks leads to confusion sometimes: for example, people tend to expect live window resizing to be faster in all apps. But since the app is responsible for drawing the content of the window (usually via the CPU) for each frame of a live resize, there's not much Quartz Extreme can do to speed things up. There will always be a difference between resizing a Preview window containing a single image and resizing a web browser window containing a complex HTML layout.

Will Apple continue to move more computation/rendering to the cards in the future since modern graphics cards are so advanced?
What is the future of QE, can it be improved?

Possibly. Graphics hardware is certainly getting more advanced, but not necessarily in ways that are beneficial to QE. GPUs aren't general-purpose processors, and there are a number of graphics-related tasks that they'll probably never be designed to handle (e.g. text glyph rasterization, HTML+CSS layout, some image processing tasks, etc.). But the rapid advancement in hardware-accelerated 3D rendering will probably continue to have pleasant side effects for the 2D world.

How would QE work with the ibm 970 (if apple went with it)?

Just the same as it does now. The architecture behind Quartz Extreme doesn't have much to do with CPU speed or type -- the Window Server wouldn't really be any easier or more difficult to port than any other OS component.

[andreas_g4]

Amen.

Cool, thx for the info!

[stew]

Originally posted by Rickster:
YThe only times the GPU would be used were when you were playing video or running an app that used OpenGL (typically to draw 3D scenes), and in those cases, the GPU was only responsible for drawing a particular area: the movie frame or the window containing 3D content.

Not entirely true. Without QuartzGL, the graphics chip is still helping with things like blitting and line drawing. If you want to see how slow your Mac would be if everything went through the CPU, boot into OS 9 without extensions and scroll a web page.

[Mark Tungston]

Thanks, i appreciate it.

The way i see it, if you don't play games....why would i really need an advanced GPU?

Also, if Apple goes with the 970 - wouldn't the bandwidth be much larger leading the way for the GPU to be a general purpose processor? Or would this not be necessary as the 970 CPU would be more than enough to handle everything unike the G4?

[Catfish_Man]

Originally posted by Mark Tungston:
Thanks, i appreciate it.

The way i see it, if you don't play games....why would i really need an advanced GPU?

Also, if Apple goes with the 970 - wouldn't the bandwidth be much larger leading the way for the GPU to be a general purpose processor? Or would this not be necessary as the 970 CPU would be more than enough to handle everything unike the G4?

Basically, Apple doesn't control how general purpose the GPU is. ATI and nVidia control that. There have been persistent hints from an ATI employee on the arstechnica mac forum that GPUs of the NV40/R400 generation might be programmable enough to offload the rest of Quartz to them. The current ones certainly aren't. If you're in the market for a new machine and you don't do heavy 3d gaming, go low end, then get a new card when they can accerate Quartz2D as well as the Quartz Compositor (this is why I have a GeForce4mx in my machine).

[stew]

Originally posted by Mark Tungston:
The way i see it, if you don't play games....why would i really need an advanced GPU?

No. In my opinion, if it's just for web surfing, emails, watching movies, etc you don't even need QuartzGL at all. Better invest that money in some RAM or a present for your loved one.

[Mark Tungston]

Originally posted by stew:
No. In my opinion, if it's just for web surfing, emails, watching movies, etc you don't even need QuartzGL at all. Better invest that money in some RAM or a present for your loved one.

i didn't say i did nothing wither


i'm a web developer....i use a ton of programming/design apps


i want a 'fastest" model but it forces me to get a top level Graphics Card

[- - e r i k - -]

Originally posted by stew:
Not entirely true. Without QuartzGL, the graphics chip is still helping with things like blitting and line drawing. If you want to see how slow your Mac would be if everything went through the CPU, boot into OS 9 without extensions and scroll a web page.

Of course this would have to be a local web page since you can't get online with an extension-less OS 9 installation