Introducing Ftrace

The kernel function tracer, Ftrace, evolved from work done by Steven Rostedt, and many others, as they were tracking down the causes of high latency. Ftrace appeared in Linux 2.6.27 and has been actively developed since then. There are a number of documents describing kernel tracing in the kernel source in Documentation/trace.

Ftrace consists of a number of tracers that can log various types of activity in the kernel. Here, I am going to talk about the function and function_graph tracers, and about the event tracepoints. In Chapter 14, Real-time Programming, I will revisit Ftrace and use it to show real-time latencies.

The function tracer instruments each kernel function so that calls can be recorded and timestamped. As a matter ...

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