Re: Cell Graphics
PZ said:
Also, if the Cell is really supposed to be so super fast (1 Tflop) then why does it need a GPU (and not just another cell chip to act like a GPU)?
Cause if you know how a GPU work you also know a CELL CPU can't be an
efficient GPU.
There are really tons of reasons why a CELL CPU wouldn't be a competetitve GPU for a given transistors budget:
1) no support for GPU remaining fixed functions pipeline (scissor, stencil, alpha, z tests..) no clipping planes, no primitives assembly, no ROPs, no primitives walking and rasterization, no primitves clipping, etc etc etc..
2) even if one wants to use SPUs as pixel shaders engines as far we know SPUs are not well suited to hide big latencies due to texture sampling.
Modern GPUs hide latencies in pixel shaders switching from a pixel to another one at per clock basis, thus hiding the time needed to fetch and filter a group of texels.
There is nothing dictating that one can't code a pure sw rasterizer on a CELL architecture.
will it be fast? Sure! will it be competetitive? no, imho.
If the GPU NVIDIA is developing for Sony is CELL based I've no doubt they customized their APU design. Moreover I'm 100% confident they implemented in silicon all that stuff you need to make a fast GPU. If you remember the infamous Visualizer scheme you know what I'm talking about.
If the NV50 is 2x NV40 then it is ~400 Gflops (or so using nVidia flops)
Does this imply that the PS3 CPU is < 400 Gflops?
If it really could dole out more flops than an NV50 then wouldn't the NV50 become a decelerator to such a massive CPU?
That's not the case, you can't rate a GPU just from gigaflop/s.
Like I just wrote above there a lot of things a GPU does very fast that a CPU wouldn't do so well..even a CELL based CPU.
At least if we are talking about 'classic' GPUs.
IF this PS3 GPU is a customized/bastardized version of the next generation GPU NVIDIA is developing for the PC market..I don't think it will be really much more exotic (regarding how rasterization work..) than current GPUs.
Shaders wise it could be even a totally new architecture, it doesn't matter at all.
ciao,
Marco