I did some rudimentary testing with AMD vs Intel on AWS recently and found that AMD lacked enough in single threaded perf that it meant they weren’t worth the savings for our workloads (Rails apps).
AMD-based AWS instances are running on first-generation Epyc processors.
Compared to the second-generation Epyc processors that Google is using, the first generation has lower clock speeds, can execute fewer instructions per clock (particularly in terms of floating-point operations), has substantially less cache, and has a more complicated memory topology that can negatively impact the performance of workloads that aren't NUMA-aware.
In short, your experience with AMD in AWS isn't relevant to Google's offerings.
Care to publish if you have anything stored away from this?
I don't work with Rails anymore but the last Rails app(single threaded, Unicorn) I worked with raw CPU compute was not the bottleneck usually as with most CRUD apps time was mostly spent in I/O. This effect was so pronounced that I had set up most scaling groups on M or R instances as the memory used by the gems was the bottleneck on the number of Rails processes I could spawn in the box without exhausting resources. However I do remember even if CPU was not the bottleneck, moving to a processor with a better single thread performance did improve the median response time at the cost of making the same request throughput costlier.
