Highest requests per second - what is considered top performance?

[iberkner]

We've been running Nginx for sometime powering a fairly high traffic
website.  The single box, dual CPU (dual core) has been serving us well
but its time to upgrade.  I've got a new system configured, quad CPU
(quad core) = 16 cores (plenty of RAM) and CentOS.  My understanding is
that even though there are 16 cores, more than 5 Nginx instances will
not greatly improve performance.

I decided to benchmark the system using a single Nginx instance and
default configuration with a static html file.  Using "ab" (locally)
with 50,000 connections and 1,000 concurrent ones I get around 10K
requests / second.  

What particular parameters should I look into adjusting to try to double
that number?  (Nginx and OS). 

What is considered top performance for a single box / instance?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,217062,217062#msg-217062