[ltt-dev] no metadata tracefile

Sun Sep 18 18:23:10 EDT 2011

* Ji Zhai (Ji.Zhai at ca.flextronics.com) wrote:
> Hi Mathieu,
> 
> After adding that sleep(5) and even sleep(10), I got some different logs (checked by using hexdump). However, I still got the following error by using the LTTV:
> 
> ** ERROR **: Undescribed event 1 in channel ust
> Aborting...
> Lttv: line 15: 26701 Aborted       $0.real $*
> 
> I have attached the tarball of the usttrace output with debug information.
> I am not sure the error came from UST or LTTV. Can you please take a look? Thanks!

Hi Zhai,

The metadata file in the trace you sent is unpopulated. What I mean by
this is that the file exists, a 4kB buffer with appropriate header is
there, but the metadata that describes the mapping between the markers
and their ID/format is missing. This therefore points to a linker
problem that causes marker.c to be unable to list the markers present in
the application. UST 0.x does require that you link your application
with libust-initializer.o in addition to libust. How did you build/link
your applications ? And what versions of compiler/linker do you use ?

Thanks,

Mathieu

> 
> Regards,
> 
> Ji
> -----Original Message-----
> From: pdumas9 at sympatico.ca [mailto:pdumas9 at sympatico.ca] On Behalf Of Mathieu Desnoyers
> Sent: Thursday, September 15, 2011 12:21 PM
> To: Ji Zhai
> Cc: Alexandre Montplaisir; ltt-dev at lists.casi.polymtl.ca
> Subject: Re: [ltt-dev] no metadata tracefile
> 
> * Ji Zhai (Ji.Zhai at ca.flextronics.com) wrote:
> > Hi Alexandre,
> > 
> > Thanks for your reply!
> > According to your suggestions, I did the followings:
> > 1. I cleaned all related libs in /usr/local/lib and /usr/lib
> > 2. Built/installed userspace-rcu-0.6.4
> > 3. Built/installed UST-0.15 with debug enable
> > 4. gcc -o foo lust foo.c
> > 
> >    The foo.c are:
> > 
> >    #include <ust/marker.h>
> > 
> >    int main(int argc, char **argv)
> >    {
> >    int v;
> >    char *st;
> > 
> >    /* ... set values of v and st ... */
> >    v = 110;
> >    st = "hello, UST";
> >    /* a marker: */
> >    trace_mark(ust, myevent, "firstarg %d secondarg %s", v, st);
> > 
> >    /* a marker without arguments: */
> >    trace_mark(ust, myotherevent, MARK_NOARGS);
> 
> Add a sleep(5) here, it will work.
> 
> This is a fundamental design bug in UST 0.x that we are fixing in UST
> 2.0. Short-lived applications don't let enough time for the consumer to
> hook on them, and there is no rendez-vous point anywhere. See the
> following comment in UST 0.15 sources:
> 
> tests/runtests:
> 
> # FIXME We disable the exit-fast test for the release. This is a known
> # problem with the current UST design that we will be working on fixing
> # in the upcoming rework for integration with the lttng-tools. We don't
> # want to flood testers with known issues, hence the choice to disable
> # the test.
> #simple_harness_run exit-fast/exit-fast.sh
> 
> Best regards,
> 
> Mathieu
> 
> > 
> >    return 0;
> >   }
> > 
> > 5. usttrace ./foo
> > 6. I got the log files in /home/root/.usttraces.
> > 7. I used LTTV(0.12.36) to review the results:
> > 
> >    lttv -m textDump -t mcb00-main-aaillax-20110914130558687771830
> > 
> > ** (process:20623): WARNING **: Trace /nas/jizhai/LTTng/mytrace/mcb00-main-aaillax-20110914130558687771830 has no metadata tracefile
> > 
> > ** (process:20623): CRITICAL **: cannot open trace mcb00-main-aaillax-20110914130558687771830
> > /home/jizhai/MyLocal/LTTng/bin/lttv: line 15: 20623 Segmentation fault      $0.real $*
> > 
> > I have attached the tar ball (foo_ust.tar.gz) for the log files. Please see the attachment.
> > 
> > My co-worker did same test on his side and sent an email for help to the mailing list:
> > 
> > http://lists.casi.polymtl.ca/pipermail/ltt-dev/2011-September/005135.html
> > 
> > In his email, there are some debug information done by him.
> > 
> > I am looking forward to get your further help! Thanks!
> > 
> > Regards,
> > 
> > Ji
> > 
> > 
> > -----Original Message-----
> > From: Alexandre Montplaisir [mailto:alexandre.montplaisir at polymtl.ca]
> > Sent: Tuesday, September 13, 2011 4:03 PM
> > To: Ji Zhai
> > Cc: ltt-dev at lists.casi.polymtl.ca
> > Subject: Re: [ltt-dev] no metadata tracefile
> > 
> > On 11-09-13 03:22 PM, Ji Zhai wrote:
> > > Hi Mathieu,
> > >
> > > Thanks for your reply!
> > > I have tried many combinations, for example, userspace-rcu-0.6.4 and
> > > ust-0.15, but still got the same kind of errors--no metadata trace
> > > tracefile.
> > > Any idea? Thanks again!
> > >
> > > Regards,
> > >
> > > Ji
> > 
> > Hi Ji Zhai,
> > 
> > Can you take a really small UST trace (a couple MB's) and upload it
> > somewhere?
> > 
> > Also make sure you are really using the latest versions (urcu 0.6.4, UST
> > 0.15 and LTTV 0.12.38). Sometimes old versions are still in the PATH
> > even if new versions got installed afterwards. On most distros, stuff in
> > /usr/local has priority over stuff in /usr.
> > 
> > 
> > Cheers,
> > 
> > --
> > Alexandre Montplaisir
> > DORSAL lab,
> > École Polytechnique de Montréal
> > 
> > 
> >  
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> 
> 
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> 
> 
> -- 
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com