Does vCPU on the chart refer to a physical ARM core and any clue how they stack up against a modern x86-64 core?
If they’re significantly cheaper to run at similar perf this is an easy win for arch agnostic things like bastion servers or purely interpreted scripting languages.
A vCPU on an A1 instance is a physical Arm core. There is no SMT (multi-threading) on A1 instances. In my experience on the platform, the performance is quite good for traditional cloud applications that are built on open source software, especially given the price. Since the Arm architecture is quite different than x86, we always recommend testing the performance with your own applications. There's really no substitute for that.
Most of the official Docker images are now multi arch. We have been using Packet.net to build the arm images. But there are many images that are not and some registries don’t support multi arch even.
How come the "ECU" ratings aren't listed for the A1 types in the pricing page?
In particular I'm wondering how the vCPU's compare to the equivalent m5 instances. I.e. a1.xlarge and m5.xlarge both have 4 vCPU's, though the a1 has half the memory. So for tasks that aren't memory bound, would these have similar performance?
ECU ratings are based on an ancient x86 benchmark, and don't really compare well with each other anymore, let alone with totally different architectures. I think they've been trying to retire it for years.
I'm disappointed that they aren't retiring the vCPU designation, too. ARM doesn't have anything like hyperthreading, so an ARM vCPU seems to equal a complete core. The a1.xl has 4 cores, 4 threads. The m5.xl has 2 cores, 4 threads.
If they’re significantly cheaper to run at similar perf this is an easy win for arch agnostic things like bastion servers or purely interpreted scripting languages.