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

From: Masami Hiramatsu
Date: Mon Oct 28 2013 - 23:20:07 EST

(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/ [SDT marker]
> libc64:setjmp => libc:setjmp@/lib64/ [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!
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory

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