Kernel Function Tracer
modulename: mcount.ko
and/orftrace.ko
and/orlibftrace.ko
and/orentry-ftrace.ko
and/ortrace_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.
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:
selects
CONFIG_KALLSYMSCONFIG_GENERIC_TRACER
CONFIG_CONTEXT_SWITCH_TRACER
CONFIG_GLOB
CONFIG_TASKS_RCU
CONFIG_TASKS_RUDE_RCU