[Dovecot] Linux SO_REUSEPORT

[Timo Sirainen]

I just read about Linux v3.9's SO_REUSEPORT feature and decided to implement it 
for Dovecot. Would be interesting to know how it works for people :) It's going 
to be in v2.2.6, which I'm planning on releasing tomorrow. Note especially the 
warning about the bug:

http://hg.dovecot.org/dovecot-2.2/rev/a991a0547daa

So the idea is that you'd do something like:

service imap-login {
  inet_listener imap {
    reuse_port = yes
  }
  process_min_avail = 4 # number of CPU cores
}

And the load should be distributed more evenly to the processes.