Quote Originally Posted by hurleybird View Post
Not what I was saying. What I was saying is that one thread is assigned to each group of five ALUs, unlike Nvidia's architecture where each ALU gets it's own thread. Because of this RV870 can only run a maximum of 1600 / 5 = 320 threads, which is way below the 1024-thread limit of DirectCompute11.
so your saying the bottleneck is the thread dispatch and it's only being used at about 31.25% if it where redesigned to use all 1024 dispatches threads at once and not have those 5 alu's grouped. 5 alu is one SIMD. changing this to be all seprate alu shouldn't be too hard, the alu's them self are quite small already.

it's seem to me it's more like what ever is easy the programs will go for shorter times to code things.
easy isn't the best possible way to do things.