[ltt-dev] [URGENT]Re: Flight Recorder Testing on Linux-2.6.32

[Mathieu Desnoyers]

* srikanth krishnakar (skrishnakar at gmail.com) wrote:
> Hello Mathieu,
> 
> In the analysis of COREDUMP using *FLIGHT_RECORDER*, what are the steps I do
> need to follow for tracing, because If i follow the steps :
> 
> 1. Connect all markers (ltt-armall)
> 
> 2. Start tracing (lttctl -Cw /tmp/trace1 trace1)
> 
> *Till here every thing is fine... w.r.t  trace methods involved. Now say If
> here I get KERNEL_PANIC, then what about my trace data that is still pending
> and needs to be written to files.*
> *I mean till I destroy the channels I will not get the trace data !! *
> 
> How do I resolve this situation !!! where kernel panics and no trace data
> available for user ?

You would need support to get your buffers from a crash dump extraction
tool (e.g. "crash"). There has been some work done on this in the past
by Fujitsu, but that was a few years ago, so I doubt it's aware of the
current LTTng buffer layout. So this is currently unsupported. Patches
are welcome. :)

Thanks,

Mathieu

> 
> Any input are appreciated !!
> 
> Thanks,
> Srikant
> 
> 
> On Mon, May 24, 2010 at 6:59 PM, srikanth krishnakar
> <skrishnakar at gmail.com>wrote:
> 
> > Hi Mathieu,
> >
> > I am trying to run through the LTTng Flight Recorder test on kernel
> > Linux-2.6.32.13.  Here are the steps I have followed :
> >
> >
> > 1. Compiled the kernel Linux-2.6.32 + Lttng support
> >
> > 2. Booted the Lttng kernel
> >
> > 3. Loaded all the necessary modules, followed by :
> >
> > 4. Ran "ltt-armall"
> >
> > 5. Then started the tracing in flight recorder mode as:
> >
> > #  lttctl -C -w /tmp/trace3 -o channel.all.overwrite=1 trace3
> >
> > 6. Then destroyed the channels, for write process to take place:
> >
> > # lttctl -D trace3
> >
> >
> > Correct me If i am going wrong in any of the above steps, that are
> > necessary for flight recorder testing.
> >
> > What is the difference do I find in normal LTTng tracing and the Flight
> > Recorder mode ? What difference does the LTTV-GUI shows for LTTng Flight
> > recorder mode ?
> > (Is LKCD any way related to core dump tracing in Flight Recorder mode ?)
> >
> > Are there any additional steps required for carrying out the tracing in
> > Flight recorder mode for CORE DUMP tracing.
> >
> > All the steps i have followed are from :
> > http://lttng.org/cgi-bin/gitweb.cgi?p=lttv.git;a=blob_plain;f=LTTngManual.html#flight
> >
> > Any pointers would be appreciated !!
> >
> > Thanks in Advance !
> >
> > Regards
> > Srikanth Krishnakar
> > **********************
> >
> 
> 
> 
> -- 
> "The Good You Do, The Best You GET"
> 
> Regards
> Srikanth Krishnakar
> **********************

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