We are entirely Linux not NetBSD and are not currently using Lua in the kernel at all. We did, however, sponsor some of Mike Pall's work on LuaJIT based on our particular workload: http://luajit.org/sponsors.html#sponsorship_perf
We use Lua for the WAF (as Mike says), but also for all request processing. This is in part because we use Nginx and in part because employ agentzh (http://agentzh.org/) and he works on OpenResty. Fairly recently we moved all processing of requests through CloudFlare to a Lua-based system inside Nginx.
That's >5B pages views per 24 hours going through LuaJIT-ed code.
We use Lua for the WAF (as Mike says), but also for all request processing. This is in part because we use Nginx and in part because employ agentzh (http://agentzh.org/) and he works on OpenResty. Fairly recently we moved all processing of requests through CloudFlare to a Lua-based system inside Nginx.
That's >5B pages views per 24 hours going through LuaJIT-ed code.