lttng regenerate metadata
lttng-regenerate — Regenerate specific data of an LTTng recording session
lttng regenerate command regenerates specific data of:
The recording session named
The current recording session (see lttng-concepts(7) to learn more about the current recording session).
See lttng-concepts(7) to learn more about recording sessions.
As of this version, the
statedump targets are
See the “EXAMPLES” section below for usage examples.
metadata target to resample the offset between the monotonic
clock and the wall time of the system, and then regenerate the metadata
More specifically, you may want to resample the wall time following a major NTP correction. As such, LTTng can trace a system booting with an incorrect wall time before its wall time is NTP-corrected. Regenerating the metadata of the selected recording session ensures that trace readers can accurately determine the event record timestamps relative to the Unix epoch.
Note that if you plan to rotate (see lttng-concepts(7) to learn more) the selected recording session, this target only regenerates the metadata stream files of the current and next trace chunks.
Important:You can only use the
metadata target when the selected
statedump target to collect up-to-date state dump information
and create corresponding event records.
This is particularly useful if the selected recording session is in
snapshot mode (
--snapshot option of the lttng-create(1)
command) or if LTTng rotates trace files for one of its channels (see
lttng-concepts(7)): in both cases, the state dump information may be
Command warning (something went wrong during the command)
1 to abort the process after the first error is
Path to the LTTng home directory.
Useful when the Unix user running the commands has a non-writable home directory.
Absolute path to the manual pager to use to read the LTTng
command-line help (with lttng-help(1) or with the
--help option) instead of
Path to the directory containing the
session.xsd recording session
configuration XML schema.
--sessiond-path general option overrides this environment
Unix user’s LTTng runtime configuration.
Default output directory of LTTng traces in local and snapshot modes.
Override this path with the
--output option of the
Unix user’s LTTng runtime and configuration directory.
$LTTNG_HOME defaults to the value of the
Example:Regenerate the metadata of the current recording session.
lttng regenerate metadata
Example:Regenerate the state dump event records of a specific recording session.
lttng regenerate statedump --session=my-session
Special thanks to Michel Dagenais and the DORSAL laboratory at École Polytechnique de Montréal for the LTTng journey.
Also thanks to the Ericsson teams working on tracing which helped us greatly with detailed bug reports and unusual test cases.