[lttng-dev] Fwd: LTTng user space data not flushed out

tujalasaikiran tujalasaikiran at gmail.com
Thu Mar 28 07:50:17 EDT 2019

---------- Forwarded message ----------
From: *Jérémie Galarneau* <jeremie.galarneau at efficios.com>
Date: Monday, March 25, 2019
Subject: LTTng user space data not flushed out
To: tujalasaikiran <tujalasaikiran at gmail.com>

Hi Tujala,

Please use the public development mailing list
(lttng-dev at lists.lttng.org) to get community support.
Private support is available through EfficiOS' support agreements.


On Sat, 23 Mar 2019 at 13:13, tujalasaikiran <tujalasaikiran at gmail.com>
> Hi,
> I'm using LTTng live mode, the "live" parameter in the below command is
the time at which data is flushed. We get zero content size packets if we
don't have any data generated from the tracer. This is true for kernel
space domain, that is getting content size zero packets. Whereas in the
user space domain, I'm not getting zero content size packets this makes the
"live viewer"  (babeltrace) to not to show any trace data until the session
> My application generates the kernel domain events frequently whereas
userspace domain events generate very rarely. Default flush time in "lttng
create" command is 1 second, this is honored in kernel domain whereas in
userspace domain not.
> Below commands, I'm using for LTTng configuration and using babel trace
viewer to view live trace.
>                   lttng create mysession --live
>                   lttng enable-event -k sched_swich
>                   lttng enable-event -u mytrace_point:tp_one
>                   lttng start
>                   babeltrace --input-format=lttng-live
>                  <---- not getting any data from babeltrace until I stop
the session------>
>                   lttng stop
>                   <--- I'm getting data from babeltrace once I stop the
lttng session  --->
>                   lttng destroy
> Thanks,
> TSK.

Jérémie Galarneau
EfficiOS Inc.
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