Does WP8 support Quad Core already?

[Bob Shiska]

Wrong. I'm not a game developer, but I have written a few hardware accelerated 3D applications. The only situation where your example is of any importance is in real-time 3D graphics, and in those cases what is being fed to the GPU is primarily vector data which is entirely resolution independent. You can feed the GPU the exact same data whether it is being rendered to a 360 x 640 display or a 2560 x 1440 display... it makes no difference. In fact, in the overwhelming majority of cases, the CPU isn't even aware of the display's resolution. That is how irrelevant the display resolution is to the CPU.

Where display resolution does come into play is in the final stages of the rendering pipeline. This involves things like rasterization, pixel shaders and anti aliasing, but this is all the domain of the GPU. The CPU isn't involved in any of those activities.

While all that is true, you're missing what else happens when you move from low to higher resolutions. With higher resolutions to play with, you start adding details. More details means you're passing more vector data to the GPU. Again, bigger bang for buck with a better GPU, but if you were able to pair a dual core Krait with a Titan, you can bet that the CPU would be severely limiting what the Titan could do. The Titan might be able to push Angry Birds to six 4K screens simultaneously because all it would have to do is rasterize (if it supported that number of pixels, talking compute ability only) and the CPU wouldn't cause any issues, but it won't challenge even a Core i3 for desktop gaming. Hyperbole, yes, but without background specifically with programming for the platform, you can't say it won't be useful. Quad core would help 1080p, not for pushing pixels but for the things developers would want to do with those extra pixcels. Whether or not it would do much at all, I can't say.

First, note that I was referencing only those statements I had quoted. It's a fact that most smartphone video processing is not done on the CPU. End of story. Obviously, we'll always be able to find a specific app with a specific feature where the CPU plays a more prominent role. However, that isn't a point worth making. My point was that general purpose CPU cores aren't involved in nearly as many operations as most people assume they are, particularly on smartphones.

Second, your certainty in regard to where video encode and image editing occurs suggests that you don't work in the software industry. Blanket statements of that sort are almost always wrong. Even on desktops/laptops more and more of those functions are being shifted away from the general purpose computing cores to more specialized units:

1. Photoshop has been shifting ever more image editing computations to the GPU.
2. QuickSync technology shows that even Intel believes video encoding is more appropriately done on dedicated hardware than on the CPU.

Considering that Smartphones aren't just computationally constrained but also power constrained, that approach makes even more sense than on desktop/laptops. In fact, that is exactly what is being done. Here is a blog post from a Qualcomm employee stating precisely that, which I'll quote:

"The technology stage is set for video acceleration in hardware on the phone. It consists of dedicated hardware in the chipset that does the compute-intensive work of encoding and decoding"

Photoshop is pushing image editing to the GPU with OpenCL. OpenCL isn't supported on WP8. DirectCompute isn't supported. Which means no apps pushing videos back to the dedicated hardware once they've left. No image editing leveraging the power of the GPU. That'll come with the Adreno 420, but for now it's all done on CPU. While it may make more sense to do this stuff on the GPU, as of now WP8 can't, so more cores would help.

Not saying that for overall experience, a quad A7 would be better than a dual Krait, but quad Krait vs dual Krait at same speed, the quad wins out. Especially with as agressive Qualcomm is in their power gating.

 

[a5cent]

While all that is true, you're missing what else happens when you move from low to higher resolutions. With higher resolutions to play with, you start adding details. More details means you're passing more vector data to the GPU.

This is why you are wrong: if we look at a typical game, the creators strive to max out scene complexity, based on what the CPU and GPU combo can handle. Notice how display resolution doesn't factor into that? If something is maxed out, it can't be raised any further. Theoretically, scene complexity could be lowered for people with "low resolution" displays, but that just complicates the source code while offering no benefit to the user. As a result, scene complexity remains roughly constant, entirely independent of display resolution. That is how this issue is handled in practice.

Some freak piece of poorly programmed software may function the way you suggest, but thankfully I'm not aware of any. At this point, it's just your word against mine. All I can do is suggest that you look at the documentation of any rendering engine of your choice. You will notice that no mention is made of any direct relationship between scene complexity and display resolution, ever, because none exists.

I can somewhat see why you might think otherwise, but that is simply not how real-time 3D software works.

Anyway, I won't be commenting on this issue any further, because it's a bit of a side show. My point is still that for WP, and in regard to 3D rendering, the idea that a 1080p display calls for a better performing CPU is simply BS (that is all and only about the GPU).

but if you were able to pair a dual core Krait with a Titan, you can bet that the CPU would be severely limiting what the Titan could do.

I think you're starting to mix up some issues here, as this isn't what we're disputing. I would agree with that. I mentioned, scene complexity is based on what the early stages of the GPU rendering pipeline and the CPU (mutually) can handle. If you add a much faster GPU you will likely also want a faster CPU, so it can "feed" the GPU enough vertex data fast enough. Again, notice how display resolution isn't part of that sentence?

In practice, feeding the GPU fast enough is rarely a problem, because the bottleneck is almost always found somewhere in the later stages of the rendering pipeline (yes, I hate mobile GPU pixel fill rates!).

Photoshop is pushing image editing to the GPU with OpenCL. OpenCL isn't supported on WP8. DirectCompute isn't supported. Which means no apps pushing videos back to the dedicated hardware once they've left. No image editing leveraging the power of the GPU. That'll come with the Adreno 420, but for now it's all done on CPU. While it may make more sense to do this stuff on the GPU, as of now WP8 can't, so more cores would help.

You had claimed that image processing was a task only the CPU was capable of. I mentioned Photoshop only as an example of how that is not true.

As of now, WP8 can't do image processing/editing on the GPU? You'd better tell that to Nokia, they apparently didn't get that memo (Nokia developer Wiki showing how to make a lens apps filter that runs on the GPU).