Cell and RSX : their relationship.

[!eVo!-X Ant UK]

While the possibilites of cell and RSX teaming up for graphics is mind-blowing, the bandwidth is not

So i was wondering, taking in the bandwidth limmits what IS actually pssible in there connection?????

Could CELL do the HDR and RSX do the AA ????
Could CELL do the AA and RSX do the HDR?????
Could CELL do all the lighting altogher???

Is it even possible for the SPE's to even do FSAA or HDR while not eating up bandwidth?????

What can we expect them to be able to accomplish together???

 

[BlueTsunami]

Re: Cell and RSX : there relationship.

What can we expect them to be able to accomplish together???

Why did Ebony and Ivory pop into my head when I read that part of this post?....i'm scared....

 

[version]

Re: Cell and RSX : there relationship.

While the possibilites of cell and RSX teaming up for graphics is mind-blowing, the bandwidth is not

So i was wondering, taking in the bandwidth limmits what IS actually pssible in there connection?????

Could CELL do the HDR and RSX do the AA ????
Could CELL do the AA and RSX do the HDR?????
Could CELL do all the lighting altogher???

Is it even possible for the SPE's to even do FSAA or HDR while not eating up bandwidth?????

What can we expect them to be able to accomplish together???

cell do raycasting, and rsx compute only visible pixels
maybe...

 

[BenQ]

I think thats a very fair question, and a difficult one to answer.

Sure the Cell can help out in graphical areas, but I wish I knew how much bandwidth would be required for each and every graphical trick the Cell is capable of assisting the RSX with.

Obviously there are 2 limiting factors.

1. How many things can the Cell do for the RSX before bandwidth becomes the limiting factor.

2. How many things can the Cell do for the RSX before the Cell's own system resources ar compromised. Every time the Cell helps out the RSX, that means the Cell now has precisely that much less power to handle other non graphical functions such as physics, AI ect.

And how efficient is it to use the Cell as a mini GPU anyway?

 

[London Geezer]

These are all questions that will only be answered properly after a lot of games have been released. Even launch games won't exploit the hardware, so we'll have to wait till the developers get their heads round the platform, and find ways to use the SPEs and see what the performance is. And it will take a long time.

 

[nAo]

Re: Cell and RSX : there relationship.

!eVo!-X Ant UK:
I don't want to be offensive here..but you should at least know what are you taking about before asking questions, shouldn't you?

 

[BenQ]

Re: Cell and RSX : there relationship.

!eVo!-X Ant UK:
I don't want to be offensive here..but you should at least know what are you taking about before asking questions, shouldn't you?

I disagree with you completely.

What's wrong with his questions? He simply wants to have a greater understanding. There are quite a few VERY knowledgable people on this board, and a greater number of people who know much less.

How is he supposed to "know what he's talking about" if he doesn't feel free to ask questions?

If you feel his questions are too simple and not based in as much understanding as you would like to see them, then perhaps you could provide him with some links to reletive articles so he could read up about it on his own.

 

[London Geezer]

One could argue that he's asking the questions because he doesn't know... How is he supposed to know if he doesn't ask...

I mean the Search function on the forum is way too advanced for normal internet users.

We should answer every questions even when it's impossible to answer and when we can answer, repeat what's been discussed here 9807 times before.

 

[nAo]

1) I don't have to provide anything (and anything I provided before can be found with the big search button ; )
2) most of his questions don't make sense at all

 

[The GameMaster]

Re: Cell and RSX : there relationship.

While the possibilites of cell and RSX teaming up for graphics is mind-blowing, the bandwidth is not

So i was wondering, taking in the bandwidth limmits what IS actually pssible in there connection?????

Could CELL do the HDR and RSX do the AA ????
Could CELL do the AA and RSX do the HDR?????
Could CELL do all the lighting altogher???

Is it even possible for the SPE's to even do FSAA or HDR while not eating up bandwidth?????

What can we expect them to be able to accomplish together???

No to all questions... short answer. HDR, FSAA, and lighting is part of the graphics pipeline and as such is the responsibility of the GPU itself. The Cell CPU itself is actually quite limited in what graphics functions it can do instead of the GPU and the there is an extreme level of difficulty of having the CPU take over some of the duties from the GPU. You can't simply have the Cell augment the RSX because of the way the GPU is designed, though there are a few areas it can help out in. Remember the RSX is basically designed like a PC part as it is based on the Geforce 7800 series and this means the GPU is SUPPOST to handle the vast majority of the graphics tasks. You COULD try to do something in software completely and have the GPU output the results or you can use the RSX to handle the graphics... but I seriously doubt you will ever see the PS3 utilize an hybrid solution where the Cell CPU does part of the scene and the RSX handles the other part of the scene.

The XBox360's setup is more conducive to having XENON help out XENOS, thanks to the UMA architecture as well as certain functions built into XENOS itself (MEMEXPORT)... but I would imagine there would be significant difficulty in getting XENON to work with XENOS to augment the GPU's abilities.

 

[Titanio]

Re: Cell and RSX : there relationship.

While the possibilites of cell and RSX teaming up for graphics is mind-blowing, the bandwidth is not

So i was wondering, taking in the bandwidth limmits what IS actually pssible in there connection?????

Could CELL do the HDR and RSX do the AA ????
Could CELL do the AA and RSX do the HDR?????
Could CELL do all the lighting altogher???

Is it even possible for the SPE's to even do FSAA or HDR while not eating up bandwidth?????

What can we expect them to be able to accomplish together???

No to all questions... short answer. HDR, FSAA, and lighting is part of the graphics pipeline and as such is the responsibility of the GPU itself.

Yes, because CPUs are functionally a subset of GPUs.

Oh wait.

I'm not saying the specific things mentioned will be done on CPUs, but saying that everything a GPU could do HAS to be done on the GPU isn't correct. Some things you certainly wouldn't do on a CPU (and maybe the above two issues are among them) but others could be done (and would have have a hard time being done on the GPU to boot).

 

[The GameMaster]

I am probably using the wrong context in my response... but I am going to have to leave it at that.

 

[ShootMyMonkey]

Could CELL do the HDR and RSX do the AA ????
Could CELL do the AA and RSX do the HDR?????
Could CELL do all the lighting altogher???

most of his questions don't make sense at all

Well, the first two are nonsensical, all right, but the third is a valid question.

Lighting in software is certainly *possible*, but you're not going to get per-pixel lighting that way. It's not as if lightmapping will really die all that soon. At best, you can generate a bunch of lighting-related data for the shaders to use in software. You'd still have to do lighting in the RSX to get all your precious bump and specular.

I'd also expect some software skinning simply if for no other purpose than the fact that it prevents an insane explosion of shaders (i.e., if models are skinned in software, the GPU doesn't have to differentiate between skinned and non-skinned models) and the fact that CELL would probably handle it faster than RSX.

 

[Edge]

> "Could CELL do all the lighting altogher???

I wonder about that, as the Spiderman demo (actor Alfred Molina's head) shown by Sony at their E3 presentation, said that the complex skin lighting was being handled by CELL, but the image was rendered by the Nvidia GPU's.

 

[Shifty Geezer]

Re: Cell and RSX : there relationship.

The XBox360's setup is more conducive to having XENON help out XENOS, thanks to the UMA architecture as well as certain functions built into XENOS itself (MEMEXPORT)... but I would imagine there would be significant difficulty in getting XENON to work with XENOS to augment the GPU's abilities.

Huh?! How can you say XB360 is better set up for CPU+GPU combo partnership rendering? The MEMEXPORT function allows communication across the system RAM, whereas PS3 has a dedicated 35 GB/s from CPU to GPU for passing data between. I rate it very much the opposite and PS3 is better setup for combo processing.

And regards the thread OT, AA and HDR cannot be extracted from the rest of the system (as has been mentioned) though some like to think Cell could be used in AA work, or at least in releasing resources for RSX to do AA. There's plenty of scope for doing fun things but it's all very much an unknown ATM.

 

[gurgi]

1) I don't have to provide anything (and anything I provided before can be found with the big search button ; )
2) most of his questions don't make sense at all

Still.. the relationship between cell and rsx is the most exciting part of PS3, so why not take the opportunity to speculate about neat SPE uses? I mean, speculation and b3d are like peanut butter and chocolate heh. =)

 

[Titanio]

Re: Cell and RSX : there relationship.

And regards the thread OT, AA and HDR cannot be extracted from the rest of the system (as has been mentioned) though some like to think Cell could be used in AA work, or at least in releasing resources for RSX to do AA. There's plenty of scope for doing fun things but it's all very much an unknown ATM.

HDR is something David Kirk mentioned in his PC Watch Impress interview as a possible SPE workload if you wished, IIRC. I'm not sure why you'd want to though with HDR as good as it is on G70 (and thus RSX, presumably).

"Other" scene postprocessing is supposedly a possibility too.

I'm more excited by things going in the other end of the pipe, though, potentially. Like with lighting and basically all that normally static precalculated data that's used to feed shaders that possibly could become more realtime/dynamic with Cell involvement (binding simulation more tightly to graphics). I've not got PS3 hardware on my desk in front of me, but from the E3 demos and the comments in interviews after E3 about Cell graphics work, I'm quite excited about what might be possible (probably beyond first gen titles).

 

[Jawed]

If we're to believe that a Cell was originally intended to undertake GPU responsibilities in PS3 (presumably in addition to a Cell acting as PS3's CPU) then it's arguable that a lot of GPU tasks are realisable on Cell.

At the same time I think Sony chose NVidia for the fiddly details inside a GPU, such as the configuration of inter-stage buffers, framebuffer blending, anti-aliasing etc. - all of which are implemented as dedicated sections of hardware in a GPU and do not operate in a purely programmed way.

Out of the 1.8TFLOPs that NVidia claims for RSX, roughly 1.6TFLOPs reside in the fixed functions implemented directly in hardware (i.e. not the programmable vertex/pixel shader pipelines).

So, in my view, the short answer is that Cell is no good for post-processing tasks, after graphics rendering has started.

But in terms of providing data for rendering (such as vertex data tesselation) or computing textures (e.g. for detailed lighting effects) used as input for rendering, I think Cell has every chance at being really useful.

Jawed

 

[!eVo!-X Ant UK]

Thanks for all the reply's guys

so it seems that we might see somthing very special crop up later in PS3's life from the cell, RSX relationship.

 

[Carl B]

I don't know that the original GPU design was going to be 'just another Cell' though. The Visualizer patent seems to indicate a Cell-based design, to be sure - but with some definite tweaks. If we knew more about their original GPU plans and how they originally intended Cell (the CPU) and Cell (the GPU) to work together, we might have a better idea of how that concept might have been adapted to the new situation.

It could be that a number of benefits the CPU could have brought originally might have needed to be dropped, and some other possibilities have cropped up. Well, I mean rather obviously this is the case - it's just to what degree.

Also on the side makes one wonder if the PS3 was originally going to be UMA, since the supposed Cell GPU would have been able to access XDR just fine.