How use callgrind/kcachegrind with rubyonrails

Hi, all:
I have installed callgrind/kcachegrind in my kubuntu for monitoring
the process performance of my RoR program.
But I encounter a problem as a jackaroo of callgrind/kcachegrind. How
could I monitor my ruby contoller or model files? Is there any tips?
Thanks very much!!


NO one have used it before? Then how could people evaluate the
bottleneck of RoR program?