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

[Pekka Enberg]

On 10/26/2013 02:16 PM, 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.

Thanks for providing numbers to the discussion. AFAICT, we
might even be able to just scan everything for 'perf list' by
default.

                    Pekka
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