Excuse me while I shill for my employer but we're indeed big fans of BPF at Facebook.
Our L4 load balancer is implemented entirely in BPF byte code emitting C++ and relies on XDP for "blazing fast" (comms approved totally scientific replacement for gbps and pps figures...) packet forwarding. It's open source and was discussed here at HN before https://news.ycombinator.com/item?id=17199921.
We discussed how we use eBPF for traffic shaping in our internal networks at Linux Plumber's Conference http://vger.kernel.org/lpc-bpf2018.html#session-9
We presented how we enforce network traffic encryption, catch and terminate cleartext communication, again, you guessed, with BPF at Networking@Scale https://atscaleconference.com/events/networking-scale-3/ (video coming soon, I think.)
Firewalls with BPF? Sure we have 'em. http://vger.kernel.org/lpc_net2018_talks/ebpf-firewall-LPC.p...
In addition to all these nice applications we heavily rely on fleet wide tooling constructed with eBPF to monitor:
- performance (why is it slow? why does it allocate this much?)
- correctness (collect evidence it's doing its job like counters and logs. this should never happen, catch if it does!)
> - performance (why is it slow? why does it allocate this much?)
One of the pieces of fleet-wide tooling that heavily uses eBPF is PyPerf, which we talked about publicly at Systems@Scale in September ("Service Efficiency at Instagram Scale" - https://atscaleconference.com/events/systems-scale-2/ - video also coming soon, I think).
Is there any public code for these perf tools?