I've got a webserver running Ubuntu 10.04 Server edition (on rackspace cloud), running nginx and jetty. It's under quite a bit of load (60-70 requests/sec or so successful). Nginx is proxying requests to jetty, but it seems that the connection times out all the time:
2011/05/19 16:43:17 [error] 17798#0: *652139 connect() failed (110: Connection timed out) while connecting to upstream
Even worse, this seems to happen to every connection on the machine: incoming connections to nginx, nginx to (localhost) jetty, even incoming ssh connections occasionally time out.
What are the network parameters that need to be tuned on a heavily used ubuntu server?