[ltt-dev] net extended trace openin error with LTTV (without attachment)

Mon Feb 8 10:24:50 EST 2010

Hi Ben,

I have been working with LTTng lately and the more I know it, the more I 
like it! 

I've also been able to open and examine traces, and it looks very 
interesting. 

I've also tried to create my own, but I've ran into an error, could you 
take a look?

Basically, I receive an error 
(ERROR:tracefile.c:1582:ltt_update_event_size: assertion failed: (info != 
NULL)) every time i try to open a net_extended trace with LTTV.

Here's what i've done:

1. Downloaded the patched kernel: git clone 
git://git.kernel.org/pub/scm/linux/kernel/git/compudj/linux-2.6-lttng.git
2. Compiled the kernel with these options (.config):
#
# GCOV-based kernel profiling
#
# CONFIG_GCOV_KERNEL is not set
CONFIG_SLOW_WORK=y
# CONFIG_SLOW_WORK_DEBUG is not set
CONFIG_LTT=y
CONFIG_LTT_FILTER=m
CONFIG_HAVE_LTT_DUMP_TABLES=y
CONFIG_LTT_RELAY=y
CONFIG_LTT_RELAY_LOCKLESS=y
# CONFIG_LTT_RELAY_IRQOFF is not set
# CONFIG_LTT_RELAY_LOCKED is not set
CONFIG_LTT_SERIALIZE=y
CONFIG_LTT_FAST_SERIALIZE=y
CONFIG_LTT_TRACEPROBES=m
CONFIG_LTT_TRACE_CONTROL=y
CONFIG_LTT_TRACER=y
CONFIG_LTT_ALIGNMENT=y
CONFIG_LTT_CHECK_ARCH_EFFICIENT_UNALIGNED_ACCESS=y
# CONFIG_LTT_DEBUG_EVENT_SIZE is not set
CONFIG_LTT_USERSPACE_EVENT=m
CONFIG_LTT_VMCORE=y
CONFIG_LTT_STATEDUMP=m
CONFIG_LTT_KPROBES=m
# CONFIG_LTT_ASCII is not set
3. Install the kernel and boot it up
4. Load all the modules
modprobe -v ltt-trace-control
modprobe -v ltt-marker-control
modprobe -v ltt-tracer
modprobe -v ltt-serialize
modprobe -v ltt-relay
modprobe -v ipc-trace
modprobe -v kernel-trace
modprobe -v mm-trace
modprobe -v net-trace
modprobe -v fs-trace
modprobe -v jbd2-trace
modprobe -v ext4-trace
modprobe -v syscall-trace
modprobe -v trap-trace
modprobe -v ltt-statedump
#extended trace
modprobe -v net-extended-trace
5. ltt-armall -n
6. lttctl -C -w /tmp/tr1 tr1
7. wget http://google.com
8. lttctl -D tr1
9. lttv -m textDump -t tr1
**
ERROR:tracefile.c:1582:ltt_update_event_size: assertion failed: (info != 
NULL)
/usr/local/bin/lttv: line 15:  2083 Aborted                 $0.real $*
10. lttv -m textDump -t tr1 --verbose --debug --edebug
net.udpv4_rcv_extended: 1003.743082325 (/tmp/tr1/net_0), 1878, 1878, 
gnome-terminal, , 1, 0x0, SOFTIRQ { skb = 0xC4BBC240, saddr = 3576624693, 
daddr = 3232235780, unicast = 1, ulen = 110, source = 53, dest = 39087, 
data_start = a299884901000100 }
Event header (tracefile /tmp/tr1/net_0 offset bb8):
     bb8    40 C2 BB C4 
**
ERROR:tracefile.c:1582:ltt_update_event_size: assertion failed: (info != 
NULL)
/usr/local/bin/lttv: line 15:  2104 Aborted                 $0.real $*

The installed versions are:
Linux Trace Toolkit Visualizer 0.12.29-02022010
Linux Trace Toolkit Trace Control 0.79-01022010

Here's the created trace for reference: 
http://www.mit.bme.hu/~paljak/trace.tgz

If I don't use net extended, than it works just fine. And I've also had 
success open your example trace.

Do you have any idea why do I get this error and how could I correct it?

Thank you in advance!

Cheers,
Gergely

p.s. Sorry for the large attachment in the previous mail, now I've 
replaced it with a link.

From:
Benjamin Poirier <benjamin.poirier at polymtl.ca>
To:
paljak at mit.bme.hu
Cc:
ltt-dev at lists.casi.polymtl.ca
Date:
2010.02.03 21:09
Subject:
Re: LTTng net_extended_trace - example data

Hello Gergely,

You can find a set of traces, results57, which work with the newest lttv 
at
http://lttng.org/~ben/results57.tar.bz2

These work with lttv 0.12.29
http://lttng.org/files/packages/lttv-0.12.29-02022010.tar.gz
and with the current git head.

Compile and install lttv from the tar archive, then run:
lttv-gui --sync --sync-stats -t results57/node1 -t results57/node2
If you are confortable building from git, you can compile and then run:
./runlttv -a"--sync --sync-stats" results57/node*

These traces showcase two programs: "broadcaster" which is a traffic
generator and an ssh session, which is more interesting.

Have a look around time 3092s, pid 1896 on node2 is the ssh client and
pid 1927 on node1 is the sshd server. The two are running on different
machines but the traces align accurately. In this case, the average
accuracy is +/- 28us. You can compare this without synchronization:
rerun lttv without the --sync options. The client and server are miles
appart.

If you'd like to try out advanced synchronization options, have a look
at lttv/lttv/sync/README. If you encounter problems or have further
questions, you are welcome to contact me or the ltt-dev mailing list 
again.

-Ben

paljak at mit.bme.hu wrote:
> Dear Benjamin,
>
> I am writing about your net_extended_trace extension to LTTng, I am
> evaluating it for a project. I looked up your e-mail announcing it on
> the lttng-dev mailing list, and I wanted to download the sample data
> from here: http://hal.drap.polymtl.ca/results55.tar.bz2 , but it is no
> longer available.
>
> Could you send it by e-mail or make it available somewhere online? I'd
> like to check out a sample before digging too deep into LTTng if it
> fits the needs of the project.
>
> Thank you very much in advance!
>
> Yours sincerely,
> Gergely
>
> -- 
> Gergely Paljak
> PhD Student
> Budapest University of Technology and Economics 

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