[lttng-dev] Beginner question: how to inspect scheduling of multi-threaded user application?

[jonathan.r.julien@gmail.com (Jonathan Rajotte)]

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On Wed, Aug 24, 2016 at 12:35 PM, Jonathan Rajotte <
jonathan.r.julien at gmail.com> wrote:

> Hi,
>
> On Aug 24, 2016 12:18 PM, "Francis Deslauriers" <
> francis.deslauriers at mail.utoronto.ca> wrote:
> >
> > Hi David,
> > If you specifically want to trace the scheduling of the threads of your
> app, you don't need custom tracepoints.
> > Enabling the sched_switch kernel event will give you both of cpu id and
> thread id. Look at the cpu_id and next_tid fields.
> >
> > You can enable the sched_switch event using : lttng enable-event -k
> sched_switch
>
> In TraceCompass you can inspect this data with the control flow view and
> the Ressource view under the Kernel analysis node under the trace node in
> the project explorer.
>
> I'm not sure of the base requirement for those views you can use the safe
> enable-event:
>

replace "safe" by "easiest".


> lttng enable-event -k 'sched*'
>
>
> You can also use "lttng track" to limi the gathering of event to a certain
> pid.
>
>
> Another way to reduce the scope would be to filter per procname:
>
>
> lttng create
> lttng add-context -k -t procname
> lttng enable-event 'sched*' --filter '$ctx.procname == "PROCNAMEHERE"'
>
lttng start


PROCNAMEHERE can contain '*' wildcard. See the man page for more
information.

Cheers



> >
> > Cheers,
> > Francis
> >
> >
> > 2016-08-24 3:17 GMT-04:00 David Aldrich <David.Aldrich at emea.nec.com>:
> >>
> >> Hi
> >>
> >>
> >>
> >> I am new to tracing in Linux and to lttng. I have a multi-threaded user
> application and I want to see:
> >>
> >>
> >>
> >> 1)      When the threads are scheduled to run
> >>
> >> 2)      Which cores the threads are running on.
> >>
> >>
> >>
> >> I have installed lttng on Ubuntu 14.04 LTS.  I am expecting to
> visualise the trace using TraceCompass.
> >>
> >>
> >>
> >> I have read the following doc section:
> >>
> >>
> >>
> >> http://lttng.org/docs/#doc-tracing-your-own-user-application
> >>
> >>
> >>
> >> In order to collect my trace, must I define custom tracepoint
> definitions ( in a tracepoint provider header file ), and insert
> tracepoints into my user application, or is there a simpler way of
> achieving my goal?
> >>
> >>
> >>
> >> Best regards
> >>
> >>
> >>
> >> David
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> lttng-dev mailing list
> >> lttng-dev at lists.lttng.org
> >> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> >>
> >
> >
> > _______________________________________________
> > lttng-dev mailing list
> > lttng-dev at lists.lttng.org
> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> >
>



-- 
Jonathan Rajotte Julien
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