measure_elapsed_time.rb

require 'log4r'

def logger
  @@logger ||= Logger.new("#{Rails.root}/log/some_profile.log")
end

def elapsed(start_time)
  elapsed_secs = Time.now - start_time
  "#{'%2d' % (elapsed_secs/60)}:#{'%02d' % (elapsed_secs%60)}:#{('%.4f' % (elapsed_secs - elapsed_secs.floor))[-4..-1]}"
end

def test_this_method
  start_time = Time.now
  # do some time consuming stuff...
  logger.debug("Elapsed time to do stuff: #{elapsed(start_time)}")
end

This generates output like:

Elapsed time to do stuff: 1:25.0685

which reads as 1 minute, 25 secs, 685 ten thousands.