Quote Originally Posted by xsecret View Post
If Sandra uses AVX in the MM Benchmark, that's not strange. Thuban doesn't have AVX and all benchmarks using it are 10 times slower.
I don't know if you have followed bulldozer trheads but actually bulldozer has teh same throughput in all 3 modes: legacy SSE,AVX 128bit and AVX 256bit. This is because the way AMD designed their FPU(or FlexFP as they call it). You have 8 of these FMACs in 8 core chip. All of them are 128bit wide. 128bit AVX usually carries very little to no performance benefit over standard SSE(think 5-10%). This is even seen in Zambezi leaked Sisoft numbers:
Attachment 119979
As you can see 11% faster in 256bit AVX mode than in legacy SSE (128bit) mode.
With bulldozer,when you go to 256bit AVX you may even incur a small penalty ,but this is not the norm(compiler patches state up to 3% penalty and AMD encourages devs to use AVX 128 instead the 256bit one).
So point is: AVX(both 128 and 256bit) brings nothing or close to nothing since Bulldozer has same peak flops in all 3 modes I listed.
The only difference is FMA recompiled software which can bring additional 2x performance over AVX 128.At least this is what AMD listed in their HPC documents from last year. I can't find the pdf but I can link to a recent presentation which included a slide on FlexFP.A picture is worth a thousand words :
Attachment 119978
As you can see,same peak flops in all 3 cases. I rest my case .

BTW the leak that I linked above showed that Zambezi @ 2.8Ghz had 132mpix/s for SSE score and 147 for AVX.I already showed that Opterons score better than this(10% higher than Zambezi). There is no Turbo in heavy FP/SIMD mode mind you. If you use 132 score as base and not 147 (AVX one),you get for 3.6Ghz : 132x3.6/2.8=170mpix/s vs 115 for 1100T. That is 48% better and based on Zambezi leak(not Opteron's score). 1.48x 5.91pts (Thuban score) =8.74pts. This is still miles ahead of what you claim and Chinese show. Again,remember that these numbers are based on SSE score I linked above (so legacy SSE code that Cinebech uses too).