Best way to benchmark Drupal stack performance I recently asked a question regarding Drupal performance and got some great replies.

This got me thinking, what is a reliable/meaningful way to benchmark Drupal?

It's easy to say "install APC, memchached &amp; Varnish" or "install module x or y", but how can I quantify just how big of a performance gain I'm getting from each setup? Basically, a sure-fire way to compare setups and find bottlenecks to squeeze the most possible performance from a Drupal site. What is the best method to find out?

Targetting Drupal 6.
I like jmeter, http://jakarta.apache.org/jmeter

It allows actual benchmarking of authenticated sessions, which many of the other approaches like ab do not. There's an article about using jmeter with authenticated users at this link