Railsbench
Install
#sudo gem install railsbench
(install path on my mac: /opt/local/lib/ruby/gems/1.8/gems/railsbench-0.9.0)
Configuration
1. set $RAILS_ROOT
eg. on my mac, edit ~/.bash_profile, add a path as below:
export RAILS_ROOT=”/Users/suave/rubyapps/rails_app”
2. #railsbench base
or
#eval ‘railsbench path’
3. #sudo railsbench postinstall
Prepare your application
1. #railsbench install
(copy benchmarks.rb and benckmarks.yml to your rails_app/config, copy benchmarking.rb to your rails_app/config/environments)
2. edit benchmarks.yml as what you want
Run railsbench
#railsbench perf_run 100 -bm=all
(”all” is a target specified in benchmarks.yml)
Environments
RAILS_ROOT
must be set to point to your rails app
RAILS_PERF_DATA
performance data sets will be stored into this directory
if not set, $HOME will be used
RAILS_PERF_RUNS
the number of times perf_loop will run perf_bench on a single invocation
if not set, 3 runs will be performed
RAILS_BENCHMARK_FILE
perf_bench send it’s output to this file
See http://railsbench.rubyforge.org/ or README under your railsbench install path to know more 
Tags: performance, rails, railsbench