doc/man/lttng-regenerate.1.txt

   1 lttng-regenerate(1)
   2 ===================
   3 :revdate: 30 April 2021
   4
   5
   6 NAME
   7 ----
   8 lttng-regenerate - Regenerate specific data of an LTTng tracing session
   9
  10
  11 SYNOPSIS
  12 --------
  13 Regenerate the metadata of a tracing session:
  14
  15 [verse]
  16 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *regenerate metadata* [option:--session='SESSION']
  17
  18 Regenerate the state dump event records of a tracing session:
  19
  20 [verse]
  21 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *regenerate statedump* [option:--session='SESSION']
  22
  23
  24 DESCRIPTION
  25 -----------
  26 The `lttng regenerate` command regenerates specific data of:
  27
  28 With the option:--session='SESSION' option::
  29     The tracing session named 'SESSION'.
  30
  31 Without the option:--session option::
  32     The current tracing session (see man:lttng-concepts(7) to learn more
  33     about the current tracing session).
  34
  35 See man:lttng-concepts(7) to learn more about tracing sessions.
  36
  37 As of this version, the `metadata` and `statedump` targets are
  38 available.
  39
  40
  41 Regenerate the metadata of a tracing session
  42 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  43 Use the `metadata` target to resample the offset between the monotonic
  44 clock and the wall time of the system, and then regenerate the metadata
  45 stream files.
  46
  47 More specifically, you may want to resample the wall time
  48 following a major
  49 link:https://en.wikipedia.org/wiki/Network_Time_Protocol[NTP]
  50 correction. As such, LTTng can trace a system booting with an incorrect
  51 wall time before its wall time is NTP-corrected. Regenerating the
  52 metadata of the selected tracing session ensures that trace readers can
  53 accurately determine the event record timestamps relative to the
  54 Unix epoch.
  55
  56 Note that if you plan to rotate (see man:lttng-concepts(7) to learn
  57 more) the selected tracing session, this target only regenerates the
  58 metadata stream files of the current and next trace chunks.
  59
  60 [IMPORTANT]
  61 ====
  62 You can only use the `metadata` target when the selected
  63 tracing session:
  64
  65 * Is not in live mode (nloption:--live option of
  66   man:lttng-create(1)).
  67
  68 * If it has user space channels, they're configured to use a
  69   per-user buffering scheme (nloption:--buffers-uid option of
  70   man:lttng-enable-channel(1)).
  71 +
  72 See man:lttng-concepts(7) to learn more about channels.
  73 ====
  74
  75
  76 Regenerate the state dump event records of a tracing session
  77 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  78 Use the `statedump` target to collect up-to-date state dump information
  79 and create corresponding event records.
  80
  81 This is particularly useful if the selected tracing session is in
  82 snapshot mode (nloption:--snapshot option of the man:lttng-create(1)
  83 command) or if LTTng rotates trace files for one of its channels (see
  84 man:lttng-concepts(7)): in both cases, the state dump information may be
  85 lost.
  86
  87
  88 include::common-lttng-cmd-options-head.txt[]
  89
  90
  91 option:-s 'SESSION', option:--session='SESSION'::
  92     Regenerate specific data of the tracing session named 'SESSION'
  93     instead of the current tracing session.
  94
  95
  96 include::common-lttng-cmd-help-options.txt[]
  97
  98
  99 include::common-lttng-cmd-after-options.txt[]
 100
 101
 102 include::common-footer.txt[]
 103
 104
 105 SEE ALSO
 106 --------
 107 man:lttng(1),
 108 man:lttng-concepts(7)