[lttng-dev] LTTng streams not Hung up even session is destroyed

[sai kiran]

Hi,
The reason for reader timer option is, UST event throughput is very low so
if I don't use this option I'm not at all getting UST trace data. Even
though the difference between "reader-timer" and "switch-timer" is not
clear for me. Correct me if I wrong,

 "Switch-Timer": After switch timer expires, Consumer daemon will take the
current sub-buffer data and new trace data will be written to next
sub-buffer (if available). So switch between sub-buffer will happen.
"Reader-Timer": After Reader-Timer expires, Consumer daemon will check
sub-buffer is full or not. If Full then consumer daemon will take the data
or else consumer daemon won't take trace data.

I'm using my own application.

Thanks,
T SAI KIRAN.

On Wed, Aug 1, 2018 at 10:43 PM, Jonathan Rajotte-Julien <
jonathan.rajotte-julien at efficios.com> wrote:

> Hi Sai,
>
> On Wed, Aug 01, 2018 at 10:05:30PM +0530, sai kiran wrote:
> > Hi,
> >  I'm using LTTng 2.9.4  version of lttng-tools, lttng-modules, and
> > lttng-ust. I'm doing tracing in Xilinx Zynq ZC706 evaluation kit.
> > the sequence of commands used for tracing:
> > Mode:
> > live mode.
>
> What is the reason behind using the live feature here since you are running
> things locally (lttng-relayd/--set-url 127.0.0.1)?
>
> Are you doing live analysis or performing analysis after the
> fact?
>
> In other word, what are you trying to achieve with tracing?
>
> I just want to make sure that you are using the most appropriate way of
> tracing
> to achieve your goal.
>
> > For relay daemon:
> > lttng-relayd -L tcp://127.0.0.1:5344--output=/tmp/lttnglogs/
> > Session commds:
> > 1) lttng create my-session --live --set-url=net://127.0.0.1
> > 2) lttng enable-channel --kernel --subbuf-size=131072 --num-subbuf=8
> > channel0
> > 3) lttng enable-channel -u --read-timer=2000000 channel0
>
> Are you sure you want to use the read-timer option?
>
> Using 2000000 as its value mean that userspace subbuffers status will only
> be checked
> upon each 2 seconds.
>
> > 4) lttng enable-event --kernel
> > sched_process_fork,sched_process_exit,irq_handler_
> entry,irq_handler_exit,sched_switch,sched_waking
> > -c channel0 --session=my-session
> > 5) lttng enable-event -u kernelprofiler:kernelprofiler_task_drop -c
> > channel0 --session=mysession
> > 6) lttng start
> > 7) lttng stop
> > 8) lttng destroy
> >
> > Here my application has a tracepoint of
> > "kernelprofiler:kernelprofiler_task_drop"
> > event.
> >
>
> > > Hi,
> > >
> > > After LTTng session is destroyed, no stream is “*Hung up*”.
> Continuously
>
> What do you mean by "Hung up"? Are you using babeltrace and connecting to
> the
> lttng-relayd daemon on localhost?
>
> What is your expectation?
>
> Do you mean that you are still receiving data on babeltrace side even when
> performing a lttng stop/destroy command?
>
> > > I’m getting data from “*relay daemon*”. I’ve killed consumer daemon,
> even
> > > though tracing data coming from relay daemon.
>
> This can happen if babeltrace is "catching-up" on the data, keep in mind
> that
> lttng-relayd have the trace data and can continue to send information to a
> babeltrace client even if the consumerd/sessiond is killed or the session
> stopped/destroyed.
>
> > > Please help me. One more
> > > thing application is running infinitely.
>
> Which application? Your application? Babeltrace? lttng-sessiond?
>
> If you are talking about your application, could you provide a backtrace
> indicating that ust is the culprit here?
>
> Cheers
>
> --
> Jonathan Rajotte-Julien
> EfficiOS
>
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