Booting 5000 Erlangs on Ampere One 192-core

Summary

Booting 5000 Erlangs on Ampere One 192-core 2025-08-05 Underjord is an artisanal consultancy doing consulting in Elixir, Nerves with an accidental speciality in marketing and outreach. If you like the writing you should really try the pro version. In the previous post on 500 virtual linux devices on ARM64 I hinted that I expected serious improvements if we got KVM working. Well. We’re there. Let’s see what we got going on. Disclosure: I am running a conference called Goatmire Elixir which Ampere is a sponsor of. This post is not part of the sponsorship exchange as such. It is prep for my talk for the conference which uses the hardware they lent me. So this is your transparency notice, but fundamentally I am not making comparisons on whether they are better or not. I’m learning and sharing about qemu and virtual Linux machines. Now I’d love if they paid me to shill them a bit later and I’d be transparent about that too. But this is not that :) To recap. We have an Ampere One 192-core machine with 1 TB of RAM. The goal is to run as many virtual Linux IoT devices using the Nerves framework. We got 500 of them last time before I tried pushing any further. I also got a bit further on the same setup when I tried. Maybe 1000, I don’t recall exactly. But there have been developments, so read on! Briefly on Nerves: the framework treats the BEAM virtual machine like the OS and essentially only uses Linux for a kernel, drivers and the like. This means we can write much if not all of the embedded device in a productive high-level language running on a provenly robust and reliable environment with memory safety and solid recovery strategies. And it means your cloud integration developer doesn’t risk seg-faulting the entire device while mangling JSON back and forth. Nerves also brings some best-practice tooling and conventions. Your init process is erlinit, your updates use fwup to provide A/B partitions and factory reset, auto-failback, validation of firmware viability, disk enc...