Unixcop published a tutorial about using Apache Bench to test the Nginx FastCGI cache.

Nginx - Using Apache Bench To Test FastCGI Cache

In this post you will use Apache Bench To Test FastCGI Cache Introduction Apache Bench (ab), developed by the Apache organization, is a command-line utility to benchmark the performance of web servers. In this article we’re going to test our installation of Nginx (from previous articles) and its configuration. 

Nginx - Using Apache Bench To Test FastCGI Cache - Unix / Linux the admins Tutorials