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| author | Steven Rostedt <srostedt@redhat.com> | 2009-01-15 19:12:40 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-16 12:15:32 +0100 |
| commit | 5361499101306cfb776c3cfa0f69d0479bc63868 (patch) | |
| tree | 1acf51a942abe6582e08ed86b4bbb98f9c095c89 /kernel/trace/trace.c | |
| parent | 6c1a99afbda99cd8d8c69d756387041567a13d87 (diff) | |
| download | lwn-5361499101306cfb776c3cfa0f69d0479bc63868.tar.gz lwn-5361499101306cfb776c3cfa0f69d0479bc63868.zip | |
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 <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index dcb757f70d21..3c54cb125228 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -835,10 +835,10 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data, trace_function(tr, data, ip, parent_ip, flags, pc); } -static void ftrace_trace_stack(struct trace_array *tr, - struct trace_array_cpu *data, - unsigned long flags, - int skip, int pc) +static void __ftrace_trace_stack(struct trace_array *tr, + struct trace_array_cpu *data, + unsigned long flags, + int skip, int pc) { #ifdef CONFIG_STACKTRACE struct ring_buffer_event *event; @@ -846,9 +846,6 @@ static void ftrace_trace_stack(struct trace_array *tr, struct stack_trace trace; unsigned long irq_flags; - if (!(trace_flags & TRACE_ITER_STACKTRACE)) - return; - event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), &irq_flags); if (!event) @@ -869,12 +866,23 @@ static void ftrace_trace_stack(struct trace_array *tr, #endif } +static void ftrace_trace_stack(struct trace_array *tr, + struct trace_array_cpu *data, + unsigned long flags, + int skip, int pc) +{ + if (!(trace_flags & TRACE_ITER_STACKTRACE)) + return; + + __ftrace_trace_stack(tr, data, flags, skip, pc); +} + void __trace_stack(struct trace_array *tr, struct trace_array_cpu *data, unsigned long flags, - int skip) + int skip, int pc) { - ftrace_trace_stack(tr, data, flags, skip, preempt_count()); + __ftrace_trace_stack(tr, data, flags, skip, pc); } static void ftrace_trace_userstack(struct trace_array *tr, |