PC Watch (my translation): PS3 Evaluation System, and much,

[Pozer]

1. You can let Xenos handle all the load balancing

2. If you let the X360's CPU handle all the vertex processing and dedicate the GPU to only pixel processing you may see a net gain in the overall amount of processing power available to you.

Interestingly, I wonder If any latter generation game engines will utilize this type of flexibility "on the fly" to maximize performance. I could see a benefit say to switch vertex usage scenarios between an indoor level and then an outdoor level type situation.

like GTA type game.....

Indoor level using 1 CPU core for Vertex and 100% of Xenos for Pixel processing.

Outdoor level going to a Xenos load balancing type situation and moving the CPU vertex core for enviroment physics calcualtions.

Of course Im talking out of my butt here.....

 

[seismologist]

On Xenos you can have all of the shaders do vertex or pixel work on RSX you cannot. If you're PS limited on RSX the VS just sits idle and the CPU cannot assist in PS work. Correct me if I'm wrong but that is my understanding. If CELL can offload some PS work then I stand corrected.

I hate to keep going in circles but go look at the numbers for G70 pixel shader performance vs. Unified shader configured in 100% pixel mode. Maybe you'll feel differently about this.

It is extremely rare for any game to be vertex bound. So rare that typical GPU's (Non-unified shaders) typically have 3-4 Pixel Shading units for every Vertex Shading unit. In truth, there should never be a situation where you have to revert back to the CPU for Vertex Shader operations.

yeah that's what I've heard too but after seeing these million polygon character demos I'm being careful not to make any assumptions

 

[PC-Engine]

go look at the numbers for G70 pixel shader performance vs. Unified shader configured in 100% pixel mode. Maybe you'll feel differently about this.

Look at the numbers? What do the numbers say? How is it relevant?

 

[Tiberius]

http://www.videogamerx.net/bbs/view.php?id=vx01&no=9810 apparently there was a developpement conference with SCEK

 

[one]

http://www.videogamerx.net/bbs/view.php?id=vx01&no=9810 apparently there was a developpement conference with SCEK
http://www.videogamerx.net/bbs/data/gamescreenshot/ps3_c01.jpg

Seems like a "Shrek" devkit was there.

 

[Fafalada]

It is extremely rare for any game to be vertex bound.

Different platform, different rules.

 

[Shifty Geezer]

The arguments in this thread are silly! If PS3's GPU is vertex bound you can offload onto CPU to help. Same with Xenos. Of course Xenos can dedicate all it's shaders to vertex work but then what's gonna do the pixel shading?!?!

On either platform the developers will have to make sure the vertex and pixel shader workload is no more than the combined hardware can cope with it. They can squeeze more vertex work onto CPU's to help, but will still need the pixel shaders running. So the CPU helping out will only be for super complex vertex-saturated situations.

In such scenes, BOTH systems will need to call on CPU to help, and BOTH will see less available CPU cycles for AI, Physics, etc. So it's down to the devs to decide how many vertices they want and how many colliding objects they want and balance resources appropriately. I don't see either platform as either being constrained relative to the other, or having a magic solution to managing all the vertex work you could ever need without sacrificing elsewhere (AI, physics or pixel shading).

 

[PC-Engine]

Can CELL help in PS?

 

[London Geezer]

I guess it "could", though i don't see many reasons for doing that.

 

[PC-Engine]

I guess it "could", though i don't see many reasons for doing that.

The reason for my question is if RSX is PS bound then CELL cannot help it with PS whereas if it's VS bound then CELL can help with VS.

 

[London Geezer]

I guess it "could", though i don't see many reasons for doing that.

The reason for my question is if RSX is PS bound then CELL cannot help it with PS whereas if it's VS bound then CELL can help with VS.

Well, word on the streets of B3D has always been that Cell's SPEs are not very useful when it comes to pixel shading... Though they are very much suited for geometry.

So, if RSX is PS limited, i guess that's its problem. Cell will be able to offload some of the geometry work, but pixel-shader-wise i think RSX is on its own.

Now that i think about it, Cell can write directly to frame buffer, so i'm sure someone will find ways to do something useful with that.

 

[!eVo!-X Ant UK]

Re: PC Watch (my translation): PS3 Evaluation System, and mu

In the PS3, the Cell and RSX are connected by a parallel interface developed by Rambus called FlexIO (Redwood), which has a wide 35GB/sec bandwidth (20GB/sec down, 15GB/sec up)

I thought it was : 35 GB/s up, 25 GB/s down

 

[V3]

Re: PC Watch (my translation): PS3 Evaluation System, and mu

In the PS3, the Cell and RSX are connected by a parallel interface developed by Rambus called FlexIO (Redwood), which has a wide 35GB/sec bandwidth (20GB/sec down, 15GB/sec up)

I thought it was : 35 GB/s up, 25 GB/s down

That's at 4 GHz, I belive. Beside 5 GB/s is taken up for southbridge interface.

 

[Shifty Geezer]

I think that's overall BW, not to RSX. Is not 35 GB/s to RSX, 25 GB/s to XDR?

V3 : FlexIO was 75 GB/s @ 4 GHz. The listed figures from SCE (not IBM) for 60 GB/s are I think correct for 3.2 GHz PS3 Cell.

 

[V3]

Can CELL help in PS?

For post processing type PS, I am pretty sure it can.

 

[V3]

V3 : FlexIO was 75 GB/s @ 4 GHz. The listed figures from SCE (not IBM) for 60 GB/s are I think correct for 3.2 GHz PS3 Cell.

You're right. I was thinking the figure was at 4GHz because I thought they didn't used all the lanes available for PS3.

 

[PC-Engine]

Can CELL help in PS?

For post processing type PS, I am pretty sure it can.

Why would you want to post process on the CPU?

 

[V3]

Can CELL help in PS?

For post processing type PS, I am pretty sure it can.

Why would you want to post process on the CPU?

Because those SPEs are pretty damn good at it.

 

[!eVo!-X Ant UK]

I guess it "could", though i don't see many reasons for doing that.

The reason for my question is if RSX is PS bound then CELL cannot help it with PS whereas if it's VS bound then CELL can help with VS.

Well, word on the streets of B3D has always been that Cell's SPEs are not very useful when it comes to pixel shading... Though they are very much suited for geometry.

So, if RSX is PS limited, i guess that's its problem. Cell will be able to offload some of the geometry work, but pixel-shader-wise i think RSX is on its own.

After seeing the graphics rendered by cell, the ducks, the gas station, GETAWAY3.... i can say that i dont cell is a useless at doin PS as people think.

 

[London Geezer]

I guess it "could", though i don't see many reasons for doing that.

The reason for my question is if RSX is PS bound then CELL cannot help it with PS whereas if it's VS bound then CELL can help with VS.

Well, word on the streets of B3D has always been that Cell's SPEs are not very useful when it comes to pixel shading... Though they are very much suited for geometry.

So, if RSX is PS limited, i guess that's its problem. Cell will be able to offload some of the geometry work, but pixel-shader-wise i think RSX is on its own.

After seeing the graphics rendered by cell, the ducks, the gas station, GETAWAY3.... i can say that i dont cell is a useless at doin PS as people think.

No one said it is useless, it's just that compared to a proper GPU, you might want to use the SPEs for something that suits them more than PS instructions.

I'm pretty sure SPEs will be able to produce some nice framebuffer effects, if the bandwidth can hold it.