Kernel Function Tracer

modulename: mcount.ko

and/or

ftrace.ko

and/or

libftrace.ko

and/or

entry-ftrace.ko

and/or

trace_functions.ko

configname: CONFIG_FUNCTION_TRACER

Linux Kernel Configuration
└─>Tracers
└─>Kernel Function Tracer
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
Enable the kernel to trace every kernel function. This is done
by using a compiler feature to insert a small, 5-byte No-Operation
instruction at the beginning of every kernel function, which NOP
sequence is then dynamically patched into a tracer call when
tracing is enabled by the administrator. If it's runtime disabled
(the bootup default), then the overhead of the instructions is very
small and not measurable even in micro-benchmarks.

source code: