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Hi Raph, first of all thank you for all of your contributions and writings - I've learned a ton from reading your blog! A minor quibble amidst your good compar

Hi Raph, first of all thank you for all of your contributions and writings - I've learned a ton from reading your blog! A minor quibble amidst your good comparison above ;) For a zen5 core, we have 16-wide SIMD with 4 pipes; 2 are FMA (2 flop), and 2 are FADD @ ~5GHZ. I math that out to 16 * 6 * 5 = 480 GFLOP/core... am I missing something?

raphlinus 2y ago
Thanks for the kind words and the clarification. I'm sure you're right; I was just multiplying things together without taking into account the different capabilities of the different execution units. Hopefully that doesn't invalidate the major points I was making.
adrian_b 2y ago
According to the initial reviews, it appears that when 512-bit instructions are executed at the maximum rate, this increases the power consumption enough so that the clock frequency drops to around 4 GHz for a 9950X So a 9950X can do 256 FMA + 256 FADD for FP64 or 512 FMA + 512 FADD for FP32, per clock cycle. Using FP32, because it can be compared with the GPUs, there are 1536 Flop per clock cycle, therefore about 6 FP32 Tflop/s @ 4 GHz for a 9950X (around 375 FP32 Gflop/s per core, but this number is irrelevant, because a single active core would go to a much higher clock frequency, probably over 5 GHz). For an application that uses only FMA, like matrix multiplication, the throughput would drop to around 4 FP32 Tflop/s or 2 FP64 Tflop/s. The values for the FP32 throughput are similar to those of the best integrated GPUs that exist at this time. Therefore doing graphics rendering on the CPU on a 9950X might be similarly fast to doing graphics rendering on the iGPU on the best mobile CPUs. Doing graphics rendering on a 9950X can still leverage the graphics and video specific blocks contained in the anemic GPU included in 9950X, whose only problem is that it has a very small number of compute shaders, but their functions can be augmented by the strong CPU.

raphlinus 2y ago

Thanks for the kind words and the clarification. I'm sure you're right; I was just multiplying things together without taking into account the different capabilities of the different execution units. Hopefully that doesn't invalidate the major points I was making.

adrian_b 2y ago

According to the initial reviews, it appears that when 512-bit instructions are executed at the maximum rate, this increases the power consumption enough so that the clock frequency drops to around 4 GHz for a 9950X So a 9950X can do 256 FMA + 256 FADD for FP64 or 512 FMA + 512 FADD for FP32, per clock cycle. Using FP32, because it can be compared with the GPUs, there are 1536 Flop per clock cycle, therefore about 6 FP32 Tflop/s @ 4 GHz for a 9950X (around 375 FP32 Gflop/s per core, but this number is irrelevant, because a single active core would go to a much higher clock frequency, probably over 5 GHz). For an application that uses only FMA, like matrix multiplication, the throughput would drop to around 4 FP32 Tflop/s or 2 FP64 Tflop/s. The values for the FP32 throughput are similar to those of the best integrated GPUs that exist at this time. Therefore doing graphics rendering on the CPU on a 9950X might be similarly fast to doing graphics rendering on the iGPU on the best mobile CPUs. Doing graphics rendering on a 9950X can still leverage the graphics and video specific blocks contained in the anemic GPU included in 9950X, whose only problem is that it has a very small number of compute shaders, but their functions can be augmented by the strong CPU.