Given a 6 year console cycle, silicon process tech will advance 3 generations. That'll translate into roughly 8 times (2^3) the transistor density of 90nm process tech.
It's obvious that vendors will continue down the path of multiple cores. It equally obvious, IMO, that rasterization isn't going anywhere, so we'll see GPUs with 2-4x the transistors of G80.
The increased density will put emphasis on performance/power - and dogmatically so.
Second biggest consideration will be design of the memory subsystem.
Looking at trends going from last gen (XBOX, PS2) to current gen (360, PS3), we went from having approximately 2 FLOPS per byte/s bandwidth in the CPUs to around 10-15 FLOPS per byte/s bandwidth. Main memory latency also increase ten fold measured in CPU cycles. Current gen. is much more limited by the memory system than last gen.
Slapping 8 times the cores in next gen systems would be pushing things way past the point of diminishing returns. It would be hard enough to manually orchestrate 60 SPUs, having to reduce contention from 60 cores hitting the same bus interface would make grown men cry.
A lot of effort will have to be put in to the memory system. We'll see large on-die and on-substrate memories, caches for the CPUs and back-buffer memories for the GPUs.
I'd imagine 720 having 16-32 out-of-order PPC cores (something like PA-Semiconductor's 3+1 way superscalar) with a 16-32MB L2/3 cache. I'd imagine Sony sticking with CELL but improving the PPU (hopefully a lot), so we'll see a 4-8 PPU, 24-32 SPU thing from them, with the rest of the die real estate being sunk into a massive shared cache (for the SPUs and PPUs).
Cheers
It's obvious that vendors will continue down the path of multiple cores. It equally obvious, IMO, that rasterization isn't going anywhere, so we'll see GPUs with 2-4x the transistors of G80.
The increased density will put emphasis on performance/power - and dogmatically so.
Second biggest consideration will be design of the memory subsystem.
Looking at trends going from last gen (XBOX, PS2) to current gen (360, PS3), we went from having approximately 2 FLOPS per byte/s bandwidth in the CPUs to around 10-15 FLOPS per byte/s bandwidth. Main memory latency also increase ten fold measured in CPU cycles. Current gen. is much more limited by the memory system than last gen.
Slapping 8 times the cores in next gen systems would be pushing things way past the point of diminishing returns. It would be hard enough to manually orchestrate 60 SPUs, having to reduce contention from 60 cores hitting the same bus interface would make grown men cry.
A lot of effort will have to be put in to the memory system. We'll see large on-die and on-substrate memories, caches for the CPUs and back-buffer memories for the GPUs.
I'd imagine 720 having 16-32 out-of-order PPC cores (something like PA-Semiconductor's 3+1 way superscalar) with a 16-32MB L2/3 cache. I'd imagine Sony sticking with CELL but improving the PPU (hopefully a lot), so we'll see a 4-8 PPU, 24-32 SPU thing from them, with the rest of the die real estate being sunk into a massive shared cache (for the SPUs and PPUs).
Cheers
