[_msw_]

Disclosure: I work for AWS.

See https://twitter.com/cperciva/status/1211125881264934917 for one example of working with FreeBSD.

  It's truly awesome that I can send an email to Amazon 
  saying "we're seeing an odd performance issue here" and
  get back "here's a FreeBSD kernel patch I just wrote which
  provides a 10% performance boost".
  
  And people claim that Amazon never contributes back to
  open source...

I linked the patches here. Not all of the work is from an AWS engineer: https://twitter.com/_msw_/status/1220088310443307008

  https://reviews.freebsd.org/D23322
  https://reviews.freebsd.org/D23323
  https://reviews.freebsd.org/D23324
  https://reviews.freebsd.org/D23325