Does Ps3 need RSX or can Cell do his work?

Texturing and rasterization (i.e. figuring out the pixel area that is covered by a triangle) have traditionally been much more efficient on dedicated hardware. That, and very fast depth and stencil handling, are the big advantages of dedicated GPUs.

I think CBE@3.2GHz has a slight (~25%) theoretical advantage over RSX when it comes to shader throughput, but that's only one item on a long list of things a GPU needs to do.

Cell alone could not come close to delivering the games we have on PS3 currently.
A machine with two CBEs might be in a roughly similar performance ballpark, although most likely still below the current PS3 setup. And that's the theory where all hardware is utilized efficiently.

In practice, the level of abstraction offered by GPUs is well understood and much more comfortable to work with than a pool of SPEs rendering triangles. That's an extra strike against software rendering.

 

The Cell isn't really going to beat the RSX at its own game. As Rolf N said, dedicated h/w is good at what it does. However, it gets in to a gray area when you start talking about other things, like more complex post processing (e.g. building sum tables).

To answer your question - It's not "impossible" for the Cell to do the work of the RSX. It's just not a very good use of the h/w.

There *is* another side to the story though - if you start talking about rendering that's not based on triangle rasterization, then you open up the door for the Cell. e.g. ray-tracing. But again, you don't exactly want the rsx just sitting idle, either.

An interesting experiment for someone might be to try and use the RSX as GPGPU and the SPUs for rendering via ray-tracing or something different. Or some other weirder mix.

Mike.

 

I'm sure once upon a time some super geniuses would try this sort of thing at University just for a laugh. It's a shame PS3 hasn't attracted these people. What's the best a Lunx renderer is managing at the moment?

 

Just for laughts and my layman curiosity as well, how would it perform in voxel rendering if the original plans of sony had come to reality with 2 cells instead of the cell+rsx, lets say, if it had 512MB for each cell instead of 256

 

Mike - Do you feel there's enough flexibility to the RSX to run as a GPGPU and not just GPGPU-ish?

 

The op actually suggests replacing the RSX with a Cell like device, compare the rumors of that Sony originally considered the PS3 to have two Cells and no RSX.

So you'd not have to worry about the RSX sitting idle in this scenario.

 

As Mike says, you're never going to beat it at it's own game (rasterization), but I've had great success using it to suplement the processing activities of the RSX. The title I'm currently working on actually does the vast majority of lighting on the SPUs in parallel with the RSX rendering independent views, which I certainly do not consider to be a poor use of the hardware .

 

yes Ive spoken about this before, ppls/populaces attention spans are becoming shorter + shorter, I shudder to think what it will be like in 50years, prolly exactly like portreyed in some sci-fi dystopia's,
WRT cell specific I know Im disappointed about this, ppl could be doing amazing stuff with it, yet noones really trying

 

I'd love to hear more about that whenever you're ready to share. Maybe even do a small feature on it for our new Beyond3d podcast. Just let us know if / when you're interested / able to (project may well be under wraps at this point, I imagine).

It doesn't happen to be Hustle Kings, does it? I'm so looking forward to that game.

 

Hustle Kings is a good example of a title Cell should excel at. It's dead-simple CSG primitives, meaning a realtime raytracer would be a perfect fit. So far though I haven't seen proper reflections which I was expecting from a snooker/pool title.

 

Hi Arwin,

If you PM your email address I will try to set something up

Cheers

 

Cool! I would have sent you a PM already, but I can't yet. You probably need five more posts of something inane like that. But no problem, I created a temporary address on my own domain, go ahead and mail me at ... (done).

Thanks!

Arwin

 

Well, you must like DICE's idea of doing low res rasterization on the SPU's (latest SIGGRAPH paper about Frostbite 2.0) though being a SPU lover yourself .

 

IIRC..there's another PS3 game (that came out a long time ago..) that does exactly the same thing.

 

Err.... Heavenly ? Or Uncharted ?

 

No

 

Star Wars? (not that's not ancient)

Resistance?

 

Crap, this can go on for some time. Any clue ?

 

Well, there where alot of patents and shematics floating around at that time. Using a Cell like its known as GPU is a bad idea (and certainly never was considered), but I remember schemes that had a Cell with SPUs and rasterizer-elements hanging on the EIB.
This would`ve been an interesting pairing, SPUs could do the Vertex-work and the Pixels are done in dedicated hardware.