[lttng-dev] No trace files are generated for UST

Jérémie Galarneau jeremie.galarneau at efficios.com
Fri Dec 6 12:52:34 EST 2013


Could you launch the session daemon in verbose mode and post the logs?

lttng-sessiond -vvv --verbose-consumer

On Fri, Dec 6, 2013 at 10:51 AM, Manikandan Govindaswamy
<magov at vestas.com> wrote:
> Yes, with that LD_PRELOAD sample able to run.
>
> root@/tmp/lttng-build-root/bin # ./lttng create app
> Session app created.
> Traces will be written in /root/lttng-traces/app-20131206-174935
> root@/tmp/lttng-build-root/bin # dmesg
> root@/tmp/lttng-build-root/bin # ./lttng enable-event -u -a
> All UST events are enabled in channel channel0
> root@/tmp/lttng-build-root/bin # ./lttng start
> Tracing started for session app
> root@/tmp/lttng-build-root/bin # cd ..
> root@/tmp/lttng-build-root # cd ..
> root@/tmp # LD_PRELOAD=/tmp/lttng-build-root/lib/liblttng-ust.so.0 ./sample
> root@/tmp #
> root@/tmp #
> root@/tmp # cd lttng-build-root/
> root@/tmp/lttng-build-root # cd bin/
> root@/tmp/lttng-build-root/bin # ./lttng stop
> Waiting for data availability
> Tracing stopped for session app
> root@/tmp/lttng-build-root/bin # dmesg
> root@/tmp/lttng-build-root/bin # ./lttng destroy
> Session app destroyed
> root@/tmp/lttng-build-root/bin # cd /
> root@/ # cd root/
> root@~ # ls
> lttng-traces
> root@~ # cd lttng-traces/
> root@~/lttng-traces # ls
> root@~/lttng-traces #< no traces are generated>
>
> in ps -ef
>
> 28664 root       0:00 ./lttng-sessiond -vvv --consumerd64-path=/tmp/lttng-build-root/lib/lttng/libexec/lttng-consumerd
> 29027 root       0:00 lttng-consumerd --quiet -u --consumerd-cmd-sock /var/run/lttng/ustconsumerd64/command --consumerd-err-sock /var/run/lttng/ustconsumerd64/error
>
> Regards,
> GMK.
>
>
>
> -----Original Message-----
> From: Thibault, Daniel [mailto:Daniel.Thibault at drdc-rddc.gc.ca]
> Sent: Friday, December 06, 2013 9:14 PM
> To: Manikandan Govindaswamy; Jérémie Galarneau
> Cc: lttng-dev at lists.lttng.org
> Subject: RE: [lttng-dev] No trace files are generated for UST
>
>> As I'm using the custom image on x86 machine, i've kept the lib in /tmp/lttng-build-root/lib folder and this sample able to see the library as well.
>>
>> And the same way I able to create the trace files for kernel but not for ust. There were no dmesg as well.
>>
>> [...]
>> root@/tmp # ldd sample
>>         linux-vdso.so.1 (0x00007fff2a135000)
>>         libdl.so.2 => /lib64/libdl.so.2 (0x00007fe2cccb5000)
>>         liblttng-ust.so.0 => /tmp/lttng-build-root/lib/liblttng-ust.so.0 (0x00007fe2cca51000)
>>         [...]
>
>    Try running sample using:
>
> LD_PRELOAD=/tmp/lttng-build-root/lib/liblttng-ust.so.0 ./sample
>
>    If the LD_PRELOAD succeeds, we will know at least that liblttng-ust is reachable by sample.
>
>    The modules have nothing to do with UST: kernel and user-space tracing are essentially independent features.
>
> Daniel U. Thibault
> Protection des systèmes et contremesures (PSC) | Systems Protection & Countermeasures (SPC)
> Cyber sécurité pour les missions essentielles (CME) | Mission Critical Cyber Security (MCCS)
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-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com



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