Re: Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

(2013/10/29 2:48), Pekka Enberg wrote:
> On 10/28/13 7:31 PM, Srikar Dronamraju wrote:
>>>> But what if a system has both 32 bit libc and 64 bit libc?
>>>> Wont we could end up with 2 libc:setjmp?
>>>> Should we give some more intelligence into perf to choose the 64 bit
>>>> libc over 32 bit one?
>>> You can just trace both of them by default, no?
>>>
>> There has to be a one to one association with the event name and its
>> mapping.  Every event name will finally map to a unique inode and an
>> offset.
>>
>> One option would be for perf to look at these markers and have a
>> different event name for similar markers in different executables.
> 
> I think we are talking past each other here.
> 
> Yes, I understand that you need an fully qualified name
> for a SDT marker but there's absolutely no reason to force
> feed that to the user of 'perf trace'.
> 
> For the 32-bit and 64-bit libc case, why cannot 'perf list'
> by default print out something like:
> 
> $ perf list
> 
>    libc:setjmp [SDT marker group]
> 
> and provide a '--fully-qualified' command line option that:
> 
> $ perf list --fully-qualified
> 
> libc:setjmp => libc32:setjmp, libc64:setjmp      [SDT marker group]
> libc32:setjmp => libc:setjmp@/lib/libc.so.6      [SDT marker]
> libc64:setjmp => libc:setjmp@/lib64/libc.so.6  [SDT marker]
> 
> and then teach 'perf trace' to deal with SDT marker groups
> where you trace two events, not one?

Ah, that's a good idea. :)
And it also is needed for another probe event because
sometimes inlined functions have multiple instances.
I'd like to fold them as one event group.

Thank you!
-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com