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Trace Compass/Project Meetings/2016-04-01


  • Alexandre Montplaisir (EfficiOS)
  • Jonathan Rajotte (EfficiOS)
  • Matthew Khouzam (Ericsson)
  • Patrick Tassé (Ericsson)
  • Marc-André Laperle (Ericsson)
  • Jean-Christian Kouamé (Ericsson)
  • Bernd Hufmann (Ericsson)
  • Geneviève Bastien (Polytechnique)


Go over AIs of last meeting

Efficios's planned tasks for Neon

Alex is planning to finish up and push to Gerrit the following two branches:

  • UST 2.8 Symbol provider (for source lookup and callstack view)
  • LTTng-Analyses integration

ideally before mid-April.

Callstack View and Symbol Provider additions

While working on the new UST symbol provider, Alex hit some limitations of the current symbol lookup implementation:

  • There is no notion of timestamps: libraries can get loaded and unloaded so one address may not point to the same symbol for the whole duration of the trace.
  • There is no notion of process: a trace may contain events from more than one process/executable. The symbol lookup, even the addresses themselves, are completely different from one process to another.

The aforementioned branch will include some patches to add the notion of process to the callstack analysis and view, as well as new methods in the symbol provider that take a "address, timestamp, pid" tuple.

LTTng Control MI XSD validation

  • According to LTTng devs, XSD validation is more a "unit test" for LTTng itself. Viewers shouldn't have to do this.
  • It was decided to drop the XSD validation in Trace Compass.
    • We won't need to import / do a CQ for the 2.8 XSD
  • However it would be useful for the MI protocol to have its own version, so that we can know if/when it does break. Jonathan mentioned it should be very easy to add.

Update on LTTng Live Reading

  • Due to several limitations, it was confirmed to disable the LTTng live tracing feature for the 2.0 release. See the discussion in:
  • Bernd also pointed out that it might be good to get feedback on actual use cases before going further ahead with this.

New LTTng Common plugin

  • Geneviève prepared a patch to introduce a new lttng2.common plugin.
  • This plugin would contain things common to both UST and kernel traces, like some aspect definitions.
  • Everyone was fine with it.

Action Items

  • None

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