Fix: invalid discarded events on start/stop without event production
authorJonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Wed, 17 Jun 2020 19:55:36 +0000 (15:55 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Wed, 17 Jun 2020 21:57:28 +0000 (17:57 -0400)
commitd9b063d707b3f6d0a0c7e3a30eb6b9faa9a5f5e3
treed38032981eb6f2825b7eef67071b40d2800a0f20
parentdbbc5b0a971a544a1b79dcf9d172259140dd7ac5
Fix: invalid discarded events on start/stop without event production

Observed issue
==============

On consecutive start/stop command sequence the reported discarded event
count is N * CPU, where N is the number of start/stop pair executed.

Note that no event generation occurred between each start/stop pair.

    lttng start
    lttng stop
    Tracing stopped for session auto-20200616-094338
    lttng start
    lttng stop
    Waiting for data availability
    Warning: 4 events were discarded, please refer to the documentation on channel configuration.
    Tracing stopped for session auto-20200616-094338
    lttng start
    lttng stop
    Waiting for data availability
    Warning: 8 events were discarded, please refer to the documentation on channel configuration.
    Tracing stopped for session auto-20200616-094338

The issue was bisected down to:
  commit 6f9449c22eef59294cf1e1dc3610a5cbf14baec0 (HEAD)
  Author: Jérémie Galarneau <jeremie.galarneau@efficios.com>
  Date:   Sun May 10 18:00:26 2020 -0400

  consumerd: refactor: split read_subbuf into sub-operations
  [...]

Cause
=====

The discarded event local variable, in `consumer_stream_update_stats()`
is initialized with the subbuffer sequence count instead of the
subbuffer discarded event count.

Solution
========

Use the subbuffer discarded event count to initialized the variable.

Known drawbacks
=========

None

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I5ff213d0464cdb591b550f6e610bf15085b18888
src/common/consumer/consumer-stream.c
This page took 0.03364 seconds and 4 git commands to generate.