Rails App/webserver benchmarking

Does anyone know the best lightweight Rails benchmarking tool?

I need to get performance statistics of the webserver and simulate authentication + page navigation per session. I've been trying to use httperf, but been encountering TamperingWithCookie exception in the application.

Ideally, I'd like to separate the application and database from the webserver benchmarking, but interested to see the results of the combination of these.

From stackoverflow

• You can try Tsung, a distributed load testing tool written in Erlang. It's a general tool but can be easily used with Rails applications. In case you need to simulate different user behavior scenarios as a kind of integration tests, you could also try Webrat.

• It's not the best way, but using a web stress tool like MS WAS has worked in the past to show simple benchmarks.

• ruby-prof works well either by you manually hitting your app with a browser, or it can benchmark against tests.

  here's a great writeup on how to use it: http://cfis.savagexi.com/2007/07/18/making-rails-go-vroom

  and here's where you can download it: http://rubyforge.org/projects/ruby-prof/