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What's going on in the Himeno poisson pressure benchmark? Scientific optimizations all intel processors have but AMD lack?
by et2o 9y ago
What's going on in the Himeno poisson pressure benchmark? Scientific optimizations all intel processors have but AMD lack?
- dahauns 9y agoIIRC it's rather AVX-heavy.
- CyberDildonics 9y agoZen cores actually have half sized SIMD units compare to Intel. They will execute AVX instructions, but for programs that use AVX well, Intel should win. Using AVX at all is still rare, using it well even more so, but Intel's AVX SIMD performance is pretty stellar.
- Dylan16807 9y agoYeah, the execution unit differences are really complicated. Ryzen has four ALUs plus four partial vector units. These vector units are all 128 bit. Two can add and two can multiply. An adder and a multiplier can combine to do FMA. Skylake has four math ports total, all of which can do basic ALU operations. Two of them have 256 bit vector capabilities, and each of those can add or multiply or FMA. A third has limited vector capabilities. 10 core (and higher?) Skylake-X chips upgrade those limited capabilities into an entire new 512-bit vector unit, also capable of FMA. Depending on your exact needs, Ryzen can be slower or faster than Skylake, but it's usually slower on programs stuffed full of vector math, especially FMA. I think I got that mostly correct.