Measuring running times

[Antonio D'Ettole]

Hi everybody,
as part of my project work at school I'm running some Hadoop jobs on a
cluster. I'd like to measure exactly how long each phase of the process
takes: mapping, shuffling (ideally divided in copying and sorting) and
reducing. The tasktracker logs do not seem to supply the start/end times for
each phase, at least not all of them, even when the log level is set to
DEBUG.
Do you have any ideas on how I could work this out?
Thanks
Antonio