  Collecting data about the sequences of function calls executed by an
application while running in the field can be useful to a number of
applications, including failure reproduction, profiling, and debugging.
Unfortunately, collecting data from the field may introduce annoying slowdowns
that negatively affect the quality of the user experience. So far, the impact
of monitoring has been mainly studied in terms of the overhead that it may
introduce in the monitored applications, rather than considering if the
introduced overhead can be really recognized by users. In this paper we take a
different perspective studying to what extent collecting data about sequences
of function calls may impact the quality of the user experience, producing
recognizable effects. Interestingly we found that, depending on the nature of
the executed operation and its execution context, users may tolerate a
non-trivial overhead. This information can be potentially exploited to collect
significant amount of data without annoying users.
