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Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
- From: Mark Wielaard <mjw at redhat dot com>
- To: Ingo Molnar <mingo at kernel dot org>
- Cc: Pekka Enberg <penberg at iki dot fi>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, "Frank Ch. Eigler" <fche at redhat dot com>, 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: Thu, 31 Oct 2013 14:23:26 +0100
- Subject: Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:
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On Thu, 2013-10-31 at 11:57 +0100, Ingo Molnar wrote:
> * Mark Wielaard <mjw@redhat.com> wrote:
> > On Wed, 2013-10-30 at 13:51 +0200, Pekka Enberg wrote:
> > > On 10/30/13 12:05 PM, Masami Hiramatsu wrote:
> > > > 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.
> > >
> > > Good point. That definitely narrows down the scanned set.
> >
> > It is fast. But that would miss the various libjvm.so variants for
> > example. Or other programs, like libreoffice, which have SDT
> > probes in their internal shared libraries that aren't in the
> > default ldconfig paths.
>
> I suppose those Java libraries ought to show up in
> /etc/prelink.cache though, right?
Good point. Yes, all executables and libraries I was missing in ldconfig
--print-cache do show up with prelink -p.
Except libjvm.so itself... Apparently prelink is convinced that really
is never used. hmmm. Apparently all wrapper "java" executables only
dlopen it, so it is never directly linked, and prelink doesn't cache it.
But except for that special case, prelink -p is a good substitute.
Cheers,
Mark