[lttng-dev] Babeltrace performance issue in live-reading mode

[liguang.lee6@gmail.com (liguang li)]

Hi,

On Mon, Sep 18, 2017 at 11:18 PM, Jonathan Rajotte-Julien <
jonathan.rajotte-julien at efficios.com> wrote:

> Hi,
>
> On Mon, Sep 18, 2017 at 11:32:07AM +0800, liguang li wrote:
> >    Hi,
> >
> >    Create a session in live-reading mode, run a application which having
> very
> >    high event throughput, then prints
> >    the events with babeltrace. We found the live trace viewer are viewing
> >    events a few seconds ago, and as time
>
> Could you provide us the version used for babeltrace, lttng-tools and
> lttng-ust?
>

 Babeltrace: 1.5.1
 Lttng-tools: 2.8.6
 Lttng-ust: 2.8.2

>    goes on, the delay will be bigger and bigger.
>
> A similar issues was observed a couple months ago, which implicated
> multiple delayed ack
> problems during communication between lttng-relayd and babeltrace.
>
> The following fixes were merged:
>
> [1] https://github.com/lttng/lttng-tools/commit/
> b6025e9476332b75eb8184345c3eb3e924780088
> [2] https://github.com/efficios/babeltrace/commit/
> de417d04317ca3bc30f59685a9d19de670e4b11d
> [3] https://github.com/efficios/babeltrace/commit/
> 4594dbd8f7c2af2446a3e310bee74ba4a2e9d648
>
> In the event that you are already using an updated version of babeltrace
> and
> lttng-tools, it would be pertinent to provide us with a simple reproducer
> so we
> can assess the issue.
>
>
 Steps:

 lttng create session --live -U net://*
 lttng enable-channel -s session -u ch1
 lttng enable-event -s session -c ch1 -u -a
 lttng start

 Run a high event throughput application, which is multithreaded
application.

 babeltrace -i lttng-live net://*

 After a while, we found the timestamp of the event in the babeltrace is
different with the time in host
 which run the application. And the delay will be bigger and bigger with
time goes.


> Cheers
>
> >    I checked the source code, found Babeltrace in live-reading mode will
> read
> >    the recorded events in the CTF
> >    files, and then parse and print it in a single thread. The process is
> a
> >    little slow, do you have any ideas to
> >    improve the process.
> >    Thanks,
> >    Liguang
>
> > _______________________________________________
> > lttng-dev mailing list
> > lttng-dev at lists.lttng.org
> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>
>
> --
> Jonathan Rajotte-Julien
> EfficiOS
>
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