First confirm that you have root privilege.
Second check the config of kernel that you have the configs on:
CONFIG_FTRACE=y CONFIG_FUNCTION_GRAPH_TRACER=y CONFIG_EVENT_TRACING=y
CONFIG_FUNCTION_TRACER CONFIG_STACK_TRACER CONFIG_DYNAMIC_FTRACE
Last you confirm you have your debugfs/tracefs mounted, by:
mount -t debugfs nodev /sys/kernel/debug/
Then go into the sys entry tracing and you will find the friendly README.
List some triggers:
options/funcgraph-irqs, tracing_on, max_graph_depth, set_graph_function, set_ftrace_filter, set_ftrace_pid, current_tracer.
stack_trace can probe runtime kernel address of functions.
ftrace: tracing linux function calls
原文：https://www.cnblogs.com/sansna/p/9866015.html