X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=doc%2Fman%2Flttng-regenerate.1.txt;h=d3f645fc6d9e381066679a9723767a491d0e3e67;hb=af1c4164dd7bad940a84c29c2b429d76e3fc0e33;hp=dbbfa4d1a3472e5530a4f05b192b1af1c6e613f8;hpb=eded6438f3b15eccc391525f653e03293a890d32;p=lttng-tools.git diff --git a/doc/man/lttng-regenerate.1.txt b/doc/man/lttng-regenerate.1.txt index dbbfa4d1a..d3f645fc6 100644 --- a/doc/man/lttng-regenerate.1.txt +++ b/doc/man/lttng-regenerate.1.txt @@ -1,58 +1,99 @@ lttng-regenerate(1) -================= +=================== +:revdate: 30 April 2021 NAME ---- -lttng-regenerate - Manage an LTTng tracing session's data regeneration +lttng-regenerate - Regenerate specific data of an LTTng tracing session SYNOPSIS -------- -Regenerate the metadata of a session +Regenerate the metadata of a tracing session: [verse] *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *regenerate metadata* [option:--session='SESSION'] +Regenerate the state dump event records of a tracing session: + +[verse] +*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *regenerate statedump* [option:--session='SESSION'] + + DESCRIPTION ----------- -The `lttng regenerate` command manages a tracing session's data regeneration -options. +The `lttng regenerate` command regenerates specific data of: + +With the option:--session='SESSION' option:: + The tracing session named 'SESSION'. -As of this version, only the `metadata` command's action is available. -Regenerating a tracing session's metadata can be used to -resample the offset between the system's monotonic clock and -the wall-clock time. +Without the option:--session option:: + The current tracing session (see man:lttng-concepts(7) to learn more + about the current tracing session). -This command is meant to be used to resample the wall-clock time +See man:lttng-concepts(7) to learn more about tracing sessions. + +As of this version, the `metadata` and `statedump` targets are +available. + + +Regenerate the metadata of a tracing session +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Use the `metadata` target to resample the offset between the monotonic +clock and the wall time of the system, and then regenerate the metadata +stream files. + +More specifically, you may want to resample the wall time following a major link:https://en.wikipedia.org/wiki/Network_Time_Protocol[NTP] -correction. As such, a system booting with an incorrect wall time can be -traced before its wall time is NTP-corrected. Regenerating the tracing -session's metadata ensures that trace viewers can accurately determine -the events time relative to Unix Epoch. +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 tracing 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 man:lttng-concepts(7) to learn +more) the selected tracing session, this target only regenerates the +metadata stream files of the current and next trace chunks. -include::common-cmd-options-head.txt[] +[IMPORTANT] +==== +You can only use the `metadata` target when the selected +tracing session: +* Is not in live mode (nloption:--live option of + man:lttng-create(1)). -option:-s, option:--session='SESSION':: - Manage the metadata generation of the tracing session named 'SESSION' - instead of the current tracing session. +* If it has user space channels, they're configured to use a + per-user buffering scheme (nloption:--buffers-uid option of + man:lttng-enable-channel(1)). ++ +See man:lttng-concepts(7) to learn more about channels. +==== -include::common-cmd-help-options.txt[] +Regenerate the state dump event records of a tracing session +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Use the `statedump` target to collect up-to-date state dump information +and create corresponding event records. +This is particularly useful if the selected tracing session is in +snapshot mode (nloption:--snapshot option of the man:lttng-create(1) +command) or if LTTng rotates trace files for one of its channels (see +man:lttng-concepts(7)): in both cases, the state dump information may be +lost. -LIMITATIONS ------------ -The `lttng regenerate metadata` command can only be used on kernel and -user space tracing sessions (using per-user buffering), in non-live -mode. -See man:lttng-enable-channel(1) for more information about -buffering schemes and man:lttng-create(1) for more information -about the different tracing session modes. +include::common-cmd-options-head.txt[] + + +option:-s 'SESSION', option:--session='SESSION':: + Regenerate specific data of the tracing session named 'SESSION' + instead of the current tracing session. + + +include::common-cmd-help-options.txt[] include::common-cmd-footer.txt[] @@ -60,4 +101,5 @@ include::common-cmd-footer.txt[] SEE ALSO -------- -man:lttng(1) +man:lttng(1), +man:lttng-concepts(7)