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

[Masami Hiramatsu <mhiramat at redhat dot com>]

Ingo Molnar wrote:
> * Masami Hiramatsu <mhiramat@redhat.com> 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.

OK, so I'll try to implement it and see how it works out:-)

-- 
Masami Hiramatsu

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

e-mail: mhiramat@redhat.com