Quote Originally Posted by Oliverda View Post
Shrunk? Please show me me that shrunk. Your statement just based on simple a theory.

Or not. Probably that shrunk would be worse than Thuban because the crappy 32nm tech. If not then prove it please.
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A shrink typically brings you 0.6-0.7 area reduction ( ~220mm^2 for 32nm Thuban vs. 45nm Thuban ) and 10-20% higher clock ( 3.5-3.9GHz ) et ceteris paribus ( uarch wise ). So would be a 220mm^2 3.8GHz Thuban be better than today's BD ? Most likely yes, both in ST and MT workloads.
The problem is that such a Thuban would have several issues :
- I do not know how speed path limited K10.5 is with 3 cycle L1 and 12 cycle L2, in other words, getting to 3.5-4GHz might have required AMD to relax the latencies of the caches ( like 4 and 14-15 cycles respectively ).
- It lacks AVX and FMA. I can only assume a similar aproach like done with BD, use the existing 128bit FPUs and split de 256bit AVX in 2 halves to minimize area and complexity. I do not know the increase in FPU area and power to support AVX and FMA, I don't think it's trivial
-Maintains the status quo vs. Intel. Thuban roughly needs almost 2x the core count to match Intel Xeons. BD did not improve on this, it definately needs at least 2x the core count to match Intel Xeons.

Given BD's failures, it could be that at least vs. BD ver 1, a 32nm Thuban might have performed better.

Imagine we are in late 2008/ early 2009. BD simulations prove the CPU to be to large and to slow in 45nm vs. competitor CPUs. At the same time, Intel announced they will not use SSE5 and XOP but go for AVX and FMA3. This raises an interesting point : what if AMD would have planned a 32nm Thuban in summer 2011 and delay BD to 2012, drop FMA4 support, focus only on AVX and FMA3 ?
The first one should have been not that difficult to do (?) and would have bought time to polish BD. AVX and FMA4 support is more or less irrelevant now and by the time they will become widespread, BDver1 is history anyway.