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Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
- From: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: Pekka Enberg <penberg at kernel dot org>, Hemant Kumar <hkshaw at linux dot vnet dot ibm dot com>, LKML <linux-kernel at vger dot kernel dot org>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Peter Zijlstra <peterz at infradead dot org>, Oleg Nesterov <oleg at redhat dot com>, hegdevasant at linux dot vnet dot ibm dot com, Ingo Molnar <mingo at redhat dot com>, anton at redhat dot com, systemtap at sourceware dot org, Namhyung Kim <namhyung at kernel dot org>, aravinda at linux dot vnet dot ibm dot com, dsahern at gmail dot com, "yrl dot pp-manager dot tt at hitachi dot com" <yrl dot pp-manager dot tt at hitachi dot com>
- Date: Wed, 30 Oct 2013 19:05:43 +0900
- Subject: Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
- Authentication-results: sourceware.org; auth=none
- References: <20131023044511 dot 1886 dot 82571 dot stgit at hemant-fedora> <20131023050502 dot 1886 dot 15779 dot stgit at hemant-fedora> <CAOJsxLFKm3TxeTmGjbpr1r4sZ8fHcM481-5BM_Cq0J8hhtvBqQ at mail dot gmail dot com> <y0mbo2cs2oa dot fsf at fche dot csb>
(2013/10/26 20:16), Frank Ch. Eigler wrote:
> Pekka Enberg <penberg@kernel.org> 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@hitachi.com