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

[Masami Hiramatsu]

(2013/10/26 20:16), Frank Ch. Eigler wrote:
> Pekka Enberg <penberg@xxxxxxxxxx> writes:
> 
>> Is there a technical reason why 'perf list' could not show all the
>> available SDT markers on a system and that the 'mark to event'
>> mapping cannot happen automatically? [...]
> 
> A quick experiment with:
> 
>   find `echo $PATH | tr : ' '` -type f -perm -555 | 
>        xargs readelf -n 2>/dev/null | 
>        grep STAP 2>/dev/null 
> 
> suggests reasonable performance for my F19 workstation (a second or
> two over ~6000 executables), once all the ELF content is in the block
> cache.  According to a stap eventcount.stp run, that required about
> 50000 syscall.read events.
> 
> Note that a $PATH search excludes shared libraries, which can also
> carry <sys/sdt.h> markers.  Adding /usr/lib* in more than doubles the
> work, then there's /usr/libexec etc.

To find all system libraries, we can use ldconfig.

$ ldconfig --print-cache

shows what dynamic libraries will be loaded. On my own laptop (running
ubuntu13.04) shows ~1000 libs.

Thank you,

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx


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