----------------------------------------------------------------------
Date: Sun, 22 Jun 2014 19:27:31 +0400
From: Dmitri Shubin <[email protected]>
> In dtrace it's possible to check if some probe is currently enabled or not
> (to avoid argument preparation for disabled probes).
> But I'm unable to find similar feature in lttng-ust (at least it's not
> mentioned in lttng-ust man page).
>
> Am I missed it or it's not implemented on purpose?
Use the list command. A command such as 'lttng list <session_name>' will
list the known events and their enabled/disabled status. You can filter the
command's output by specifying a domain (--userspace) and/or a channel
(--channel <channel_name>). For example:
(begin example)
$ lttng create some_session
Session some_session created.
Traces will be written in /home/username/lttng-traces/
some_session-20140625-102709
$ lttng enable-event -u some_event
UST event some_event created in channel channel0
$ lttng list some_session -u --channel channel0
Tracing session some_session: [inactive]
Trace path: /home/username/lttng-traces/ some_session-20140625-102709
=== Domain: UST global ===
Buffer type: per UID
- channel0: [enabled]
Attributes:
overwrite mode: 0
subbuffers size: 131072
number of subbufers: 4
switch time interval: 0
read time interval: 0
output: mmap()
Events:
some_event (type: tracepoint) [enabled]
(end example)
You can take a look at /usr/src/lttng-tools/src/bin/lttng/commands/list.c to
see how the information is obtained.
Daniel U. Thibault
Protection des systèmes et contremesures (PSC) | Systems Protection &
Countermeasures (SPC)
Cyber sécurité pour les missions essentielles (CME) | Mission Critical Cyber
Security (MCCS)
RDDC - Centre de recherches de Valcartier | DRDC - Valcartier Research Centre
2459 route de la Bravoure
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