[ltt-dev] latest LTTng on 64bit RHEL

[Martin Kosina]

So far, my main motivation has been similar to Joachim's (i.e. profiling a
multithreaded server app with what we suspect are synchronization and i/o
scalability issues), but eventually relating the timelines to network
traffic between two traces would be extremely useful, yes.

As far as relating the instruction pointer to a stack trace in a user
process, that does seem to have tremendous potential, as well. The only
thing remotely similar I have found so far is the Intel thread profiler,
which unfortunately seems to choke on any significant number of threads for
me (well, the GUI does, anyway).



On Fri, Oct 16, 2009 at 5:26 AM, Mathieu Desnoyers <
compudj at krystal.dyndns.org> wrote:

> BTW, there are improvements to LTTV on their way that will permit to
> automatically synchronize traces collected from networked nodes from the
> TCP traffic sequence numbers or added UDP synchronization.
>
> That might be something you'd like to look at. I'm CCing Benjamin
> Poirier who is currently finishing his masters on this. He is in the
> process of integrating the resulting algorithms to LTTV.
>
> Mathieu
>
>
> * Martin Kosina (martin_kosina at yahoo.com) wrote:
> > Yep, module loading problem between the two OS flavors, sorry for the
> dumb
> > question!
> > Wonderful tool, btw, just starting to learn how to interpret all the
> > data. We are looking into a more sophisticated / continuous profiling of
> a
> > network management system that collects data from hundreds of thousands
> of
> > devices (smart power grid infrastructure), looks like LTTng might work
> very
> > well.
> >
> > Best,
> > Martin
> >
> >
> > On Thu, Oct 15, 2009 at 6:53 PM, Mathieu Desnoyers <
> > compudj at krystal.dyndns.org> wrote:
> >
> > > * Martin Kosina (martin_kosina at yahoo.com) wrote:
> > > > Hi guys,
> > > >
> > > > Are there any known issues with running LTTng on em64t, specifically
> on
> > > > RHEL5 ? The traces run normally, but are basically empty, just a
> single
> > > > "unknown process" and just a bunch of "MODE_UNKNOWN" messages in the
> > > Event
> > > > Viewer and no timelines.
> > > >
> > > > Kernel is a 2.6.30.9 (built from git://
> > > > git.kernel.org/pub/scm/linux/kernel/git/compudj/linux-2.6-lttng.giton
> > > the
> > > > traced  host), latest ltt-control, and lttv from git. Traces built
> from
> > > the
> > > > same sources on ia32 are working fine there. (The GUI is running on a
> > > 32-bit
> > > > box mounting the other machine's /tmp, FWIW).
> > > >
> > > > Thanks,
> > > > Martin
> > > >
> > > >
> > > > P.S. It all looks pretty normal when arming/running/stopping:
> > > >
> > > > [mkosina at metersim04 lttv]$ sudo /usr/local/bin/ltt-armall
> > > > Connecting all markers
> > > > Connecting /mnt/debugfs/ltt/markers/input/input_event
> > > > Connecting /mnt/debugfs/ltt/markers/irq_state/idt_table
> > > > Connecting /mnt/debugfs/ltt/markers/module_state/list_module
> > > > Connecting /mnt/debugfs/ltt/markers/softirq_state/softirq_vec
> > > > Connecting /mnt/debugfs/ltt/markers/swap_state/statedump_swap_files
> > > > Connecting /mnt/debugfs/ltt/markers/syscall_state/sys_call_table
> > > >
> > >
> > > Hrm, it looks like your LTTng probe modules are either not compiled or
> > > not loaded.
> > >
> > > Can you give us a copy of your kernel .config and lsmod output ?
> > >
> > > Mathieu
> > >
> > > > [mkosina at metersim04 lttv]$ sudo /usr/local/bin/lttctl -C
> --channel_root
> > > > /mnt/debugfs/ltt -w /tmp/trace1 -o channel.all.overwrite=0 -n 1 trace
> > > >
> > > > Linux Trace Toolkit Trace Control 0.71-30092009
> > > >
> > > > Controlling trace : trace
> > > >
> > > > lttctl: Creating trace
> > > > lttctl: Forking lttd
> > > > Linux Trace Toolkit Trace Daemon 0.71-30092009
> > > >
> > > > Reading from debugfs directory : /mnt/debugfs/ltt/trace
> > > > Writing to trace directory : /tmp/trace1
> > > >
> > > > [mkosina at metersim04 lttv]$ sudo /usr/local/bin/lttctl -D trace
> > > > Linux Trace Toolkit Trace Control 0.71-30092009
> > > >
> > > > Controlling trace : trace
> > > >
> > > > lttctl: Pausing trace
> > > > lttctl: Destroying trace
> > >
> > > > _______________________________________________
> > > > 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
>
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