-.TH "LTTNG" "1" "July 18th, 2013" "" ""
+.TH "LTTNG" "1" "May 13th, 2014" "" ""
.SH "NAME"
lttng \(em LTTng 2.x tracer control command line tool
.PP
The LTTng project aims at providing highly efficient tracing tools for Linux.
-It's tracers help tracking down performance issues and debugging problems
+Its tracers help track down performance issues and debug problems
involving multiple concurrent processes and threads. Tracing across multiple
systems is also possible.
The \fBlttng\fP command line tool from the lttng-tools package is used to control
-both kernel and user-space tracing. Every interactions with the tracer should
-be done by this tool or by the liblttng-ctl provided with the lttng-tools
+both kernel and user-space tracing. Every interaction with the tracer should
+be done by this tool or by the liblttng-ctl library provided by the lttng-tools
package.
LTTng uses a session daemon (lttng-sessiond(8)), acting as a tracing registry,
those traces is done using the babeltrace(1) text viewer.
We introduce the notion of \fBtracing domains\fP which is essentially a type of
-tracer (kernel or user space for now). In the future, we could see a third
-tracer being for instance an hypervisor. For some commands, you'll need to
-specify on which domain the command applies (-u or -k). For instance, enabling
-a kernel event, you must specify the kernel domain to the command so we know
-for which tracer this event is for.
+tracer (kernel, user space or JUL for now). In the future, we could see more
+tracer like for instance an hypervisor. For some commands, you'll need to
+specify on which domain the command operates (\-u, \-k or \-j). For instance,
+the kernel domain must be specified when enabling a kernel event.
In order to trace the kernel, the session daemon needs to be running as root.
LTTng provides the use of a \fBtracing group\fP (default: tracing). Whomever is
in that group can interact with the root session daemon and thus trace the
-kernel. Session daemons can co-exist meaning that you can have a session daemon
+kernel. Session daemons can co-exist, meaning that you can have a session daemon
running as Alice that can be used to trace her applications along side with a
-root daemon or even a Bob daemon. We highly recommend to start the session
+root daemon or even a Bob daemon. We highly recommend starting the session
daemon at boot time for stable and long term tracing.
-Every user-space applications instrumented with lttng-ust(3), will
-automatically register to the session daemon. This feature gives you the
-ability to list available traceable applications and tracepoints on a per user
-basis. (See \fBlist\fP command).
+Each user-space application instrumented with lttng-ust(3) will automatically
+register with the root session daemon and its user session daemon. This allows
+each daemon to list the available traceable applications and tracepoints at any
+given moment (See the \fBlist\fP command).
.SH "OPTIONS"
.PP
A context is basically extra information appended to a channel. For instance,
you could ask the tracer to add the PID information for all events in a
channel. You can also add performance monitoring unit counters (perf PMU) using
-the perf kernel API).
+the perf kernel API.
-For example, this command will add the context information 'prio' and two perf
-counters (hardware branch misses and cache misses), to all events in the trace
+For example, this command will add the context information 'prio' and two per-CPU
+perf counters (hardware branch misses and cache misses), to all events in the trace
data output:
.nf
-# lttng add-context \-k \-t prio \-t perf:branch-misses \\
- \-t perf:cache-misses
+# lttng add-context \-k \-t prio \-t perf:cpu:branch-misses \\
+ \-t perf:cpu:cache-misses
.fi
Please take a look at the help (\-h/\-\-help) for a detailed list of available
contexts.
+Perf counters are available as per-CPU ("perf:cpu:...") and per-thread
+("perf:thread:...") counters. Currently, per-CPU counters can only be
+used with the kernel tracing domain, and per-thread counters can only be
+used with the UST tracing domain.
+
If no channel is given (\-c), the context is added to all channels that were
already enabled. If the session has no channel, a default channel is created.
Otherwise the context will be added only to the given channel (\-c).
# lttng create calibrate-function
# lttng enable-event calibrate \-\-kernel \\
\-\-function lttng_calibrate_kretprobe
-# lttng add-context \-\-kernel \-t perf:LLC-load-misses \\
- \-t perf:LLC-store-misses \\
- \-t perf:LLC-prefetch-misses
+# lttng add-context \-\-kernel \-t perf:cpu:LLC-load-misses \\
+ \-t perf:cpu:LLC-store-misses \\
+ \-t perf:cpu:LLC-prefetch-misses
# lttng start
# for a in $(seq 1 10); do \\
lttng calibrate \-\-kernel \-\-function;
Create tracing session.
A tracing session contains channel(s) which contains event(s). It is domain
-agnostic meaning that you can enable channels and events for either the
+agnostic, meaning that channels and events can be enabled for the
user-space tracer and/or the kernel tracer. It acts like a container
aggregating multiple tracing sources.
variable LTTNG_HOME. This is useful when the user running the commands has
a non-writeable home directory.
+The session name MUST NOT contain the character '/'.
+
.B OPTIONS:
.TP
Specify output path for traces
.TP
.BR "\-\-no-output"
-Traces will not be outputted
+Traces will not be output
.TP
.BR "\-\-snapshot"
Set the session in snapshot mode. Created in no-output mode and uses the
-URL, if one, as the default snapshot output. Every channel will be set
+URL, if one is specified, as the default snapshot output. Every channel will be set
in overwrite mode and with mmap output (splice not supported).
+.TP
+.BR "\-\-live [USEC]"
+Set the session exclusively in live mode. The paremeter is the delay in micro
+seconds before the data is flushed and streamed. The live mode allows you to
+stream the trace and view it while it's being recorded by any tracer. For that,
+you need a lttng-relayd and this session requires a network URL (\-U or
+\-C/\-D). If no USEC nor URL is provided, the default is to use a timer value
+set to 1000000 and the network URL set to net://127.0.0.1.
+
+To read a live session, you can use babeltrace(1) or the live streaming
+protocol in doc/live-reading-protocol.txt. Here is an example:
+
+.nf
+$ lttng-relayd -o /tmp/lttng
+$ lttng create --live 200000 -U net://localhost
+$ lttng enable-event -a --userspace
+$ lttng start
+.fi
+
+After the start, you'll be able to read the events while they are being
+recorded in /tmp/lttng.
.TP
.BR "\-U, \-\-set-url=URL"
Discard event when subbuffers are full (default)
.TP
.BR "\-\-overwrite"
-Flight recorder mode : overwrites events when subbuffers are full
+Flight recorder mode: overwrites events when subbuffers are full. The
+number of subbuffer must be 2 or more.
.TP
.BR "\-\-subbuf-size SIZE"
Subbuffer size in bytes {+k,+M,+G}.
.BR "\-C, \-\-tracefile-size SIZE"
Maximum size of each tracefile within a stream (in bytes).
0 means unlimited. (default: 0)
+Note: traces generated with this option may inaccurately report
+discarded events as of CTF 1.8.
.TP
.BR "\-W, \-\-tracefile-count COUNT"
Used in conjunction with \-C option, this will limit the number of files
.nf
$ lttng enable-channel -k -C 4096 -W 32 chan1
.fi
-For each stream, the maximum size of each trace file will be 4096 bytes, and
+For each stream, the maximum size of each trace file will be 4096 bytes and
there will be a maximum of 32 different files. The file count is appended after
the stream number as seen in the following example. The last trace file is
smaller than 4096 since it was not completely filled.
Apply on channel name
.TP
.BR "\-a, \-\-all"
-Enable all tracepoints and syscalls. This actually enable a single
+Enable all tracepoints and syscalls. This actually enables a single
wildcard event "*".
.TP
.BR "\-k, \-\-kernel"
.BR "\-u, \-\-userspace"
Apply for the user-space tracer
.TP
+.BR "\-j, \-\-jul"
+Apply for Java application using Java Util Logging interface (JUL)
+.TP
.BR "\-\-tracepoint"
-Tracepoint event (default). Userspace tracer supports wildcards at end
+Tracepoint event (default). Userspace tracer supports wildcards at the end
of string. Don't forget to quote to deal with bash expansion.
e.g.:
.nf
.TP
.BR "\-\-loglevel NAME"
Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
+For the JUL domain, the loglevel ranges are detailed with the \-\-help
+option thus starting from SEVERE to FINEST.
.TP
.BR "\-\-loglevel-only NAME"
Tracepoint loglevel (only this loglevel).
.BR "\-\-syscall"
System call event. Enabling syscalls tracing (kernel tracer), you will
not be able to disable them with disable-event. This is a known
-limitation. You can disable the entire channel to do the trick.
+limitation. You can disable the entire channel to do the trick. Also note
+that per-syscall selection is not supported yet. Use with "-a" to enable
+all syscalls.
.TP
.BR "\-\-filter 'expression'"
Set a filter on a newly enabled event. Filter expression on event
-fields and context. Event recording depends on evaluation. Only
-specify on first activation of a given event within a session.
-Filter only allowed when enabling events within a session before
+fields and context. The event will be recorded if the filter's
+expression evaluates to TRUE. Only specify on first activation of a
+given event within a session.
+Specifying a filter is only allowed when enabling events within a session before
tracing is started. If the filter fails to link with the event
within the traced domain, the event will be discarded.
-Currently, filter is only implemented for the user-space tracer.
+Filtering is currently only implemented for the user-space tracer.
Expression examples:
Wildcards are allowed at the end of strings:
'seqfield1 == "te*"'
In string literals, the escape character is a '\\'. Use '\\*' for
-the '*' character, and '\\\\' for the '\\' character. Wildcard
-match any sequence of characters, including an empty sub-string
-(match 0 or more characters).
+the '*' character, and '\\\\' for the '\\' character sequence. Wildcard
+matches any sequence of characters, including an empty sub-string
+(matches 0 or more characters).
-Context information can be used for filtering. The examples below show
-usage of context filtering on process name (with a wildcard), process ID
-range, and unique thread ID for filtering. The process and thread ID of
+Context information can be used for filtering. The examples below shows
+usage of context filtering on the process name (using a wildcard), process ID
+range, and unique thread ID. The process and thread IDs of
running applications can be found under columns "PID" and "LWP" of the
"ps -eLf" command.
'$ctx.vtid == 1234'
.fi
+Context information is available to all filters whether or not the add-context
+command has been used to add it to the event's channel, as long as the context
+field exists for that domain. For example, the filter examples given above will
+never fail to link: no add-context is required for the event's channel.
+
+.TP
+.BR "\-x, \-\-exclude LIST"
+Add exclusions to UST tracepoints:
+Events that match any of the items in the comma-separated LIST are not
+enabled, even if they match a wildcard definition of the event.
+
+This option is also applicable with the \fB\-a, \-\-all\fP option,
+in which case all UST tracepoints are enabled except the ones whose
+names match any of the items in LIST.
.RE
.PP
.RS
Disable tracing channel
-Disabling a channel makes all event(s) in that channel to stop tracing. You can
-enable it back by calling \fBlttng enable-channel NAME\fP again.
+Disabling a channel disables the tracing of all of the channel's events. A channel
+can be re-enabled by calling \fBlttng enable-channel NAME\fP again.
If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
file.
.TP
.BR "\-u, \-\-userspace"
Apply for the user-space tracer
+.TP
+.BR "\-j, \-\-jul"
+Apply for Java application using Java Util Logging interface (JUL)
.RE
.PP
With \-k alone, it will list all available kernel events (except the system
calls events).
+With \-j alone, the available JUL event from registered application will be
+list. The event corresponds to the Logger name in the Java JUL application.
With \-u alone, it will list all available user-space events from registered
applications. Here is an example of 'lttng list \-u':
.TP
.BR "\-u, \-\-userspace"
Select user-space domain.
+.TP
+.BR "\-j, \-\-jul"
+Apply for Java application using JUL
+.TP
+.BR "\-f, \-\-fields"
+List event fields
.PP
.B SESSION OPTIONS:
.RE
.PP
+.PP
+\fBload\fP [OPTIONS] [NAME]
+.RS
+Load tracing session configuration
+
+If NAME is omitted, all session configurations found in both the user's session
+configuration directory and the system session configuration directory will be
+loaded.
+
+.B OPTIONS:
+
+.TP
+.BR "\-h, \-\-help"
+Show summary of possible options and commands.
+.TP
+.BR "\-a, \-\-all"
+Load all session configurations (default).
+.TP
+.BR "\-i, \-\-input-path PATH"
+Specify the input path for session configurations.
+.TP
+.BR "\-f, -\-force"
+Overwrite current session configuration(s) if a session of the same name
+already exists.
+.RE
+.PP
+
+.PP
+\fBsave\fP [OPTIONS] [SESSION]
+.RS
+Save tracing session configuration
+
+If SESSION is omitted, all session configurations will be saved to individual
+\fB.lttng\fP files under the user's session configuration directory (default:
+~/.lttng/sessions/ or /var/run/lttng/sessions/ for root user). The default
+session configuration file naming scheme is \fBSESSION.lttng\fP.
+
+.B OPTIONS:
+
+.TP
+.BR "\-h, \-\-help"
+Show summary of possible options and commands.
+.TP
+.BR "\-a, \-\-all"
+Save all session configurations (default).
+.TP
+.BR "\-o, \-\-output-path PATH"
+Specify the output path for saved sessions. This overrides the default session
+configuration directory.
+.TP
+.BR "\-f, -\-force"
+Overwrite session configuration file if session name clashes.
+.RE
+.PP
+
.PP
\fBset-session\fP NAME [OPTIONS]
.RS
snapshot with a custom maximum size or with a different name.
.nf
-$ lttng add-output -n mysnapshot file:///data/snapshot
+$ lttng snapshot add-output -n mysnapshot file:///data/snapshot
[...]
$ lttng snapshot record -n new_name_snapshot
.fi
Name of the snapshot's output.
.TP
.BR "\-m, \-\-max-size SIZE"
-Maximum size in bytes of the snapshot. The maxium size does not include
-the metadata file.
+Maximum size in bytes of the snapshot. The maxium size does not include the
+metadata file. Human readable format is accepted: {+k,+M,+G}. For instance,
+\-\-max-size 5M
+
+The minimum size of a snapshot is computed by multiplying the total amount of
+streams in the session by the largest subbuffer size. This is to ensure
+fairness between channels when extracting data.
.TP
.BR "\-C, \-\-ctrl-url URL"
Set control path URL. (Must use -D also)
.TP
.BR "\-\-list-options"
Simple listing of options
-.TP "\-\-no-wait"
+.TP
+.BR "\-\-no-wait"
Don't wait for data availability.
.RE
.PP
.RE
.PP
+.SH "JUL DOMAIN"
+This section explains the JUL domain (\-j, \-\-jul) where JUL stands for Java
+Util Logging. You can use that feature by using the \fBliblttng-ust-jul.so\fP
+from the lttng-ust(3) project.
+
+The LTTng Java Agent uses JNI to link the UST tracer to the Java application
+that uses the agent. Thus, it behaves similarly to the UST domain (\-u). When
+enabling events with the JUL domain, you enable a Logger name that will then be
+mapped to a default UST tracepoint called \fBlttng_jul:jul_event\fP in the
+\fBlttng_jul_channel\fP. Using the lttng-ctl API, any JUL events must use the
+tracepoint event type (same as \-\-tracepoint).
+
+Because of the default immutable channel (\fBlttng_jul_channel\fP), the
+\fBenable-channel\fP command CAN NOT be used with the JUL domain thus not
+having any \-j option.
+
+For JUL event, loglevels are supported with the JUL ABI values. Use \fBlttng
+enable-event \-h\fP to list them. Wildcards are NOT supported except the "*"
+meaning all events (same as \-a).
+
+Exactly like the UST domain, if the Java application has the same UID as you,
+you can trace it. Same goes for the tracing group accessing root applications.
+
+Finally, you can list every Logger name that are available from JUL registered
+applications to the session daemon by using \fBlttng list \-j\fP.
+
+Here is an example on how to use this domain.
+
+.nf
+$ lttng list -j
+[...]
+$ lttng create aSession
+$ lttng enable-event -s aSession -j MyCustomLoggerName
+$ lttng start
+.fi
+
+More information can be found in the lttng-ust documentation, see
+java-util-logging.txt
+.PP
+
.SH "EXIT VALUES"
.PP
On success 0 is returned and a positive value on error. Value of 1 means a command
tool. You can also use \-\-sessiond-path option having the same effect.
.PP
+.PP
+.IP "LTTNG_SESSION_CONFIG_XSD_PATH"
+Set the path in which the \fBsession.xsd\fP session configuration schema may be
+found.
+.PP
+
.SH "SEE ALSO"
.BR babeltrace(1),
.BR lttng-ust(3),
.BR lttng-sessiond(8),
.BR lttng-relayd(8),
-.BR lttng-health-check(3)
.SH "BUGS"
projects / lttng-tools.git / blobdiff