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

[Mathieu Desnoyers]

* srikanth krishnakar (skrishnakar at gmail.com) wrote:
> Thanks Mathieu,
> 
> I understood now. But where exactly the* lttd with -f and -d* options are
> used ? Does this really help out in dynamic buffer extraction ??

lttd -d is to put the daemon in background. -f is to select only the
flight recorder channels (prefixed with "flight-"). See lttd --help for
details.

Thanks,

Mathieu

> 
> -srikant
> 
> On Wed, May 26, 2010 at 6:54 PM, Mathieu Desnoyers <
> compudj at krystal.dyndns.org> wrote:
> 
> > * 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
> >
> 
> 
> 
> -- 
> "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