From 5361499101306cfb776c3cfa0f69d0479bc63868 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 15 Jan 2009 19:12:40 -0500 Subject: ftrace: add stack trace to function tracer Impact: new feature to stack trace any function Chris Mason asked about being able to pick and choose a function and get a stack trace from it. This feature enables his request. # echo io_schedule > /debug/tracing/set_ftrace_filter # echo function > /debug/tracing/current_tracer # echo func_stack_trace > /debug/tracing/trace_options Produces the following in /debug/tracing/trace: kjournald-702 [001] 135.673060: io_schedule <-sync_buffer kjournald-702 [002] 135.673671: <= sync_buffer <= __wait_on_bit <= out_of_line_wait_on_bit <= __wait_on_buffer <= sync_dirty_buffer <= journal_commit_transaction <= kjournald Note, be careful about turning this on without filtering the functions. You may find that you have a 10 second lag between typing and seeing what you typed. This is why the stack trace for the function tracer does not use the same stack_trace flag as the other tracers use. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/trace.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 79c872100dd5..bf39a369e4b3 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -457,6 +457,11 @@ void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu); void update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu); +void __trace_stack(struct trace_array *tr, + struct trace_array_cpu *data, + unsigned long flags, + int skip, int pc); + extern cycle_t ftrace_now(int cpu); #ifdef CONFIG_FUNCTION_TRACER @@ -467,6 +472,8 @@ void tracing_stop_function_trace(void); # define tracing_stop_function_trace() do { } while (0) #endif +extern int ftrace_function_enabled; + #ifdef CONFIG_CONTEXT_SWITCH_TRACER typedef void (*tracer_switch_func_t)(void *private, -- cgit v1.2.2