After years of development, dozens of aborted attempts and some major restructuring, the code for uprobes (userspace probes) has finally been merged into the kernel (1, 2, 3, 4, 5 and others). This enables the kernel to insert breakpoints into code for userspace software at runtime, though currently it can only be used via the kernel’s perf events subsystem. It enables tracing software that makes use of it – such as kernel component perf and version 1.8 of systemtap – to add tracepoints to userspace software, and thus monitor the runtime behaviour of the kernel and programs at the same time.