Logging time taken for data fetch

[curiousgally]

I'm trying to log the time taken for a list grid to fetch data from the data source. Is there any method which could be called to get time elapsed on dsRequest or any other object. API's didn't help me. In the RPC tab of Developer Console i get elapsed time. I'm trying to perform a load test, hence would like to get the time logged as I'm creating a virtual load using JMeter. I tried SC.logWarn() but that shows it in the log messages console in Developer Console. Where do I find the log files of these messages. I'm using tomcat for deployment.

Thanks.