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

[Masami Hiramatsu <mhiramat@redhat.com>]

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.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com