BPF: A New Type of Software
BPF originally stood for Berkeley Packet Filter, but has been extended in Linux to become a generic kernel execution engine, capable of running a new type of user-defined and kernel-mode applications.
At Netflix we have 15 BPF programs running on cloud servers by default; Facebook has 40. These programs are not processes or kernel modules, and don’t appear in traditional observability tools. They are a new type of software, and make a fundamental change to a 50-year old kernel model by introducing a new interface for applications to make kernel requests, alongside syscalls.