[ltt-dev] Arming only a few markers in LTTng

[Mathieu Desnoyers]

* Gaurav Singh (gausinghnsit at gmail.com) wrote:
> Hi Mathieu, Pierre and others,
> 
> Following is a script ltt-arm which I use to arm only few markers for
> tracing. Please check if this is the correct implementation.
> 
> Usage: ltt-arm -m <names of markers to be armed>
> 
> #!/bin/sh
> mflag=0
> startflag=0
> zero=0
>         while getopts 'm:h' OPTION
>         do
>           case $OPTION in
>           m)    mflag=1
>                 if [ $startflag = $zero ]
>                 then
>                         echo Connecting internal_kernel_sched_schedule
>                         echo "connect internal_kernel_sched_schedule
> scheduler" > /proc/ltt
>                         MARKERS=`cat /proc/ltt|grep -v %k|awk '{print
> $2}'|sort -u|grep -v ^core_|grep -v ^locking_ |grep -v ^internal_`
>                         startflag=1
>                 fi
>                 for a in $MARKERS; do if [ $a = $OPTARG ]; then
>                 echo Connecting $OPTARG
>                 echo "connect $OPTARG default" > /proc/ltt
>                 fi;
>                 done;
>                         ;;
>           h)    printf "Help \n arguments : \n-m <names of markers seperated
> by spaces>\n"
>                         ;;
>           ?)    printf "error"
>                         exit 2
>                         ;;
>            esac
>         done
> shift $(($OPTIND - 1))
> if [ "$mflag" ]
>         then
>           for a in $*; do for b in $MARKERS; do if [ $a = $b ]; then echo
> Connecting $a; echo "connect $a default" > /proc/ltt;fi; done; done;
>         fi
> 

Hrm, given we now have the debugfs interface, I am not sure it's needed
anymore.

> also following is the patch for LTTV to solve the seg fault that I was
> getting. Again grateful if you can suggest any changes:
> 
> diff -uprN lttv_orig/lttv-0.10.0-pre11-10032008/lttv/lttv/tracecontext.c
> lttv-0.10.0-pre11-10032008/lttv/lttv/tracecontext.c
> --- lttv_orig/lttv-0.10.0-pre11-10032008/lttv/lttv/tracecontext.c 2007-11-12
> 10:03:20.000000000 +0530
> +++ lttv-0.10.0-pre11-10032008/lttv/lttv/tracecontext.c 2009-02-10
> 11:44:24.000000000 +0530
> @@ -1038,10 +1038,14 @@ skip_marker:
>  void lttv_trace_hook_remove_all(GArray **th)
>  {
>    int i;
> + if((*th)->len!=0)
> + {
>    for(i=0; i<(*th)->len; i++) {
>      g_ptr_array_free(g_array_index(*th, LttvTraceHook, i).fields, TRUE);
>    }
> +
>    *th = g_array_remove_range(*th, 0, (*th)->len);
> + }
>  }

It's already fixed by commit

r2929 | pmf | 2008-05-30 11:15:26 -0400 (Fri, 30 May 2008) | 2 lines

lttv: don't crash on empty trace

Therefore current LTTV should not be affected.

Thanks,

Mathieu

> 
> Thanks Pierre and Mathieu
> Regards
> Gaurav Singh
> 
> 
> 
> 
> On Mon, Feb 2, 2009 at 9:40 PM, Mathieu Desnoyers <
> compudj at krystal.dyndns.org> wrote:
> 
> > * Pierre-Marc Fournier (pierre-marc.fournier at polymtl.ca) wrote:
> > > Hi Gaurav,
> > >
> > > Please tell us what tracepoints from the standard ones you tried to
> > > enable. LTTV has some analyses that are pretty tied to some of them and
> > > it might not digest well that some are absent.
> > >
> > > Does it work in text dump?
> > > lttv.real -m textDump -t /tmp/your/trace
> > >
> > > Does it work in gui when the only loaded plugin is the event viewer?
> > > lttv.real -m lttvwindow -m guievents -t /tmp/your/trace
> > >
> > > If so, you might try enabling other views until it segfaults to find the
> > > culprit.
> > >
> >
> > Hi Gaurav,
> >
> > LTTV *should* support the fact that probes are missing. If you can,
> > please compile with :
> >
> > ./configure CFLAGS="-g"
> > make
> > make install
> >
> > and run through gdb
> >
> > gdb path_to/lttv.real
> > set args -m textDump -t /tmp/trace
> > or
> > set args -m guicontrolflow -t /tmp/trace
> >
> > So you can report the backtrace (bt full) when it segfaults.
> >
> > Thanks,
> >
> > Mathieu
> >
> > > Thanks
> > >
> > > pmf
> > >
> > >
> > > Gaurav Singh wrote:
> > > > Hi,
> > > >
> > > > Just a small query on ltt-armall. I tried enabling only a few markers
> > at
> > > > runtime instead of running ltt-armall. The trace was successfully
> > > > collected but viewing the trace in LTTV is giving a segmentation fault.
> > > > Has anyone tried this before?
> > > >
> > > > Regards
> > > > Gaurav
> > > >
> > > >
> > > >
> > ------------------------------------------------------------------------
> > > >
> > > > _______________________________________________
> > > > ltt-dev mailing list
> > > > ltt-dev at lists.casi.polymtl.ca
> > > > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> > >
> >
> > --
> > Mathieu Desnoyers
> > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> >

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68