Re: [Dle-develop] [PATCH -tip tracing/kprobes 0/9] tracing/kprobes, perf: perf probe and kprobe-tracer bugfixes

[Ingo M. <mi...@el...>]

* Masami Hiramatsu <mhi...@re...> wrote:

> Masami Hiramatsu wrote:
> > Ingo Molnar wrote:
> >> For example you might want to probe the point within schedule that calls
> >> switch_mm() - this could be done via:
> >>
> >>    perf probe schedule@switch_mm
> >>
> >> Or the point where 'next' gets assigned? Sure, you dont need to even
> >> open the editor, if you know the rough outline of the function you can
> >> probe it via:
> >>
> >>    perf probe schedule@'next ='
> >>
> >> Note that i was able to specify both probes without having opened an
> >> editor - just based on the general knowledge of the scheduler.
> > 
> > It may be useful for return probe too :-)
> > 
> >  perf probe schedule@return
> 
> Hmm, IMHO,
> 
> >>    perf probe schedule@switch_mm
> 
> might be confused as 'probe schedule() called from switch_mm()'.
> 
> BTW, there might be several local/inline functions which have
> same name.
> I think we'd better provide a syntax for solving this issue.
> And current syntax uses @ for this purpose as below.
> 
>  perf probe localfunc@file
> 
> Maybe, we still can use % for special matching,
> 
>  perf probe schedule%switch_mm
> 
> These can be combined with each other, as below.
> 
>  perf probe schedule@kernel/sched.c%switch_mm
> 
> Or, supporting lazy string pattern matching
>  (reusing glob matching in ftrace?)
> 
>  perf probe schedule:'switch_mm(*);'
> 
> Just my thought.

I'm not attached to any particular form of syntax here (other than it 
should be simple and obvious) - we can try and see how it works out.

	Ingo