Re: [PATCH 1/4] Add support for userspace stacktraces in tracing/iter_ctrl

Török Edwin
2008-10-27T16:16:52Z

On 2008-10-27 18:03, Ingo Molnar wrote:
> * Török Edwin <edwintorok@gmail.com> wrote:
>
>
>> Usage example:
>> mount -t debugfs nodev /sys/kernel/debug
>> cd /sys/kernel/debug/tracing
>> echo userstacktrace >iter_ctrl
>> echo sched_switch >current_tracer
>> echo 1 >tracing_enabled
>> .... run application ...
>> echo 0 >tracing_enabled
>>
>> Then read one of 'trace','latency_trace','trace_pipe'
>>
>
> okay, this makes quite a bit of sense - and sysprof already kind of
> walks down into the user-space stack. (and so does oprofile, if asked)
>
> Could you send this independently of the lock contention tracing
> patches perhaps?

Sure, and "[PATCH 2/4] Identify which executable object the userspace
address belongs to" is independent of the lock tracing part too.

Perhaps I should send these 2 patches as 3 separate patches:
- introduce save_stack_trace_user in arch/
- the ftrace parts for user stack tracing (userstacktrace >iter_ctrl)
- the sym-userobj part (which is useful if you got ASLR, otherwise you
don't have a chance to resolve the symbols later after the app is gone)

I promised the lock contention tracepoints for this weekend, I'll send
out these patches at the same time too.

Best regards,
--Edwin