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SubjectRe: [PATCH] Add function graph tracer support for ARM
On Thu, Apr 23, 2009 at 02:49:56PM -0700, Tim Bird wrote:
> Uwe � wrote:
> >> Signed-off-by: <tim.bird@am.sony.com>
> > According to Documentation/SubmittingPatches you need to provide your
> > real name in the S-o-b line.
>
> OK -that's embarrassing - I'll fix this.
> scripts/checkpatch.pl didn't catch this. I may look at adding
> something to checkpatch.pl to catch empty names.
>
> > For the lazy of us, can you point me^Uus to some documentation how to
> > use the graph tracer?
>
> It looks like Documentation/ftrace.txt is missing anything about
> function graph tracing.
>
> Should I add a section?



There is already a section in Documentation/frace.txt as well in 2.6.30 :-)



>
> Here are some quick steps:
>
> $ mount -t debugfs none /debug
> $ cd /debug/tracing/
> $ cat available_tracers
> function_graph function sched_switch nop
> $ echo function_graph >current_tracer
> $ cat trace
> # tracer: function_graph
> #
> # CPU OVERHEAD/DURATION FUNCTION CALLS
> # | | | | | | |
> ------------------------------------------
> 0) --1 => events/-5
> ------------------------------------------
>
> 0) | activate_task() {
> 0) | enqueue_task() {
> 0) | enqueue_task_fair() {
> 0) | update_curr() {
> 0) 0.000 us | calc_delta_mine();
> 0) 0.000 us | update_min_vruntime();
> 0) + 61.035 us | }
> 0) 0.000 us | place_entity();
> 0) 0.000 us | __enqueue_entity();
> 0) + 91.552 us | }
> 0) ! 122.070 us | }
> 0) ! 152.588 us | }
> 0) | check_preempt_wakeup() {
> 0) 0.000 us | update_curr();
> 0) 0.000 us | wakeup_preempt_entity();
> 0) + 61.035 us | }
>
> Clearly, my clock stinks, but that's a separate issue.


Oh, that's the first function graph trace from Arm I can see.
/me feels a bit moved...

Just one childish caprice...it would be nice to see a part of a
trace which shows specific Arm arch functions in the next changelog :-)


Thanks,
Frederic.

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