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

[Jonathan Rajotte-Julien]

On Tue, Sep 19, 2017 at 03:53:27PM +0800, liguang li wrote:
>    Hi,
>    On Mon, Sep 18, 2017 at 11:18 PM, Jonathan Rajotte-Julien
>    <[1]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

Update to babeltrace 1.5.3.

>     Lttng-tools: 2.8.6

Update to lttng-tools 2.8.8

>     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]
>      [2]https://github.com/lttng/lttng-tools/commit/b6025e9476332b75eb8184345c3eb3e924780088
>      [2]
>      [3]https://github.com/efficios/babeltrace/commit/de417d04317ca3bc30f59685a9d19de670e4b11d
>      [3]
>      [4]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.

The version you are using does not include the mentioned fixes. Please update
and redo your experiment.

Cheers

> 
>     
>     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
>      > [5]lttng-dev at lists.lttng.org
>      > [6]https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> 
>      --
>      Jonathan Rajotte-Julien
>      EfficiOS
> 
> References
> 
>    Visible links
>    1. mailto:jonathan.rajotte-julien at efficios.com
>    2. https://github.com/lttng/lttng-tools/commit/b6025e9476332b75eb8184345c3eb3e924780088
>    3. https://github.com/efficios/babeltrace/commit/de417d04317ca3bc30f59685a9d19de670e4b11d
>    4. https://github.com/efficios/babeltrace/commit/4594dbd8f7c2af2446a3e310bee74ba4a2e9d648
>    5. mailto:lttng-dev at lists.lttng.org
>    6. https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Jonathan Rajotte-Julien
EfficiOS