The authors concentrated mainly on the user behavior and the
content distributed by BitTorrent. This gives a good macro
view of BitTorrent behavior. However this measurement does
not directly shed light on the core mechanisms in BitTorrent
and their effect on its performance.
Legout et al. [22] conducted a detailed measurement study
aimed at understanding the behavior of the rarest first algorithm
and the choking algorithm on real torrents. They
instrumented a BitTorrent client and observed its performance
in several torrents. They observed the log of messages sent
or received, the log of each state change, the log of the
rate estimation, and the log of important events such as end
game mode. Their results showed that (1) the rarest first
algorithm prevents the reappearance of rare pieces and avoids