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Recently worked on migrating a number of services (largely CPU bound) to Graviton 2. It was a bit of hit and mess. For some services, it worked great. Very negligible hit to performance, and since equivalent Graviton2 instances cost 20% less, it was a no brainer. Others needed a little bit of rewrite. There were also a couple that just didn't see good performance on ARM (very branchy code)

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Interesting. Other than branchy-ness, was there anything else you think correlated to poorer performance on Graviton 2.

Branchy-ness usually also correlates with cache friendliness (e.g. branchy code is usually a server app calling lots of different functions, with lots of virtual function calls), and Graviton2 has an abnormally small L3 cache relative to its x86 competitors. If I had to hazard a guess I'd say heavily vectorized code will also perform worse especially compared to Intel instances where you have AVX-512.

Didn't read into this much yet but the smaller L3 cache makes me sad. Benchmarking will show true colors but hoping to move some DB clusters to Gravaton2.

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