[$] Using user-space tracepoints with BPF

Much has been written on LWN about dynamically instrumenting kernelcode. These features are also available to user-space code with aspecial kind of probe known as a User Statically-Defined Tracing(USDT) probe. These probes provide a low-overhead way of instrumenting user-space code and provide a convenient way to debug applicationsrunning in production. In this final article of the BPF and BCC serieswe'll look at where USDT probes come from and how you can use them tounderstand the behavior of your own applications.