Instrumentation at a glance

Here are the essential tasks involved in kernel instrumentation:

1. The instrumented microkernel (procnto-instr) emits trace events as a result of various system activities. These events are automatically copied to a set of buffers grouped into a circular linked list.
2. As soon as the number of events inside a buffer reaches the high-water mark, the kernel notifies a data-capture utility.
3. The data-capture utility then writes the trace events from the buffer to an output device (e.g., a serial port, an event file, etc.).
4. A data-interpretation facility then interprets the events and presents this data to the user.

Figure 1. Instrumentation at a glance.