xdebug collects profiling data correctly except for one service

I'm working on a large application built o开发者_高级运维n Zend Framework. One of the service calls the application makes is very slow (15s) and I'm trying to profile php with xdebug to figure out what's slowing it down. However, xdebug isn't tracking any information for that service call. It works fine with all the other service calls, just not the slow one. Is there some sort of xdebug timeout that might be causing this, or maybe some other issue? I'm about to start peppering the code with microtime() and drop xdebug since it isn't working for the one service call I want to use it for. :(

Might I suggest profiling with XHProf instead? It is much easier to track down specific function calls with XHProf instead of cachegrind.