.TH "LTTNG" "1" "December 3rd, 2012" "" ""
.SH "NAME"
-lttng \(em LTTng 2.1.x tracer control command line tool
+lttng \(em LTTng 2.x tracer control command line tool
.SH "SYNOPSIS"
Simple listing of lttng commands.
.SH "COMMANDS"
-.TP
+.PP
\fBadd-context\fP
-.nf
+.RS
Add context to event(s) and/or channel(s).
A context is basically extra information appended to a channel. For instance,
counters (hardware branch misses and cache misses), to all events in the trace
data output:
-# lttng add-context \-k \-t prio \-t perf:branch-misses \-t perf:cache-misses
+.nf
+# lttng add-context \-k \-t prio \-t perf:branch-misses \\
+ \-t perf:cache-misses
+.fi
Please take a look at the help (\-h/\-\-help) for a detailed list of available
contexts.
-If no channel is given (\-c), the context is added to all channels. Otherwise
-the context will be added only to the given channel (\-c).
+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).
If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
file.
-.fi
.B OPTIONS:
-.nf
-\-h, \-\-help
- Show summary of possible options and commands.
-\-s, \-\-session NAME
- Apply on session name.
-\-c, \-\-channel NAME
- Apply on channel name.
-\-k, \-\-kernel
- Apply for the kernel tracer
-\-u, \-\-userspace
- Apply for the user-space tracer
-\-t, \-\-type TYPE
- Context type. You can repeat this option on the command line. Please
- use "lttng add-context \-h" to list all available types.
-.fi
-
-.IP
+.TP
+.BR "\-h, \-\-help"
+Show summary of possible options and commands.
+.TP
+.BR "\-s, \-\-session NAME"
+Apply on session name.
+.TP
+.BR "\-c, \-\-channel NAME"
+Apply on channel name.
+.TP
+.BR "\-k, \-\-kernel"
+Apply for the kernel tracer
+.TP
+.BR "\-u, \-\-userspace"
+Apply for the user-space tracer
+.TP
+.BR "\-t, \-\-type TYPE"
+Context type. You can repeat this option on the command line. Please
+use "lttng add-context \-h" to list all available types.
+.RE
+.PP
-.IP "\fBcalibrate\fP"
-.nf
+.PP
+\fBcalibrate\fP [OPTIONS]
+.RS
Quantify LTTng overhead
The LTTng calibrate command can be used to find out the combined average
information (see lttng add-context \-\-help to see the list of available PMU
counters).
+.nf
# 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 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 start
# for a in $(seq 1 10); do \\
lttng calibrate \-\-kernel \-\-function;
done
# lttng destroy
-# babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* | tail \-n 1)
+# babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* \\
+ | tail \-n 1)
+.fi
The output from babeltrace can be saved to a text file and opened in a
spreadsheet (e.g. oocalc) to focus on the per-PMU counter delta between
The average result, for the i7, on 10 samples:
+.nf
Average Std.Dev.
perf_LLC_load_misses: 5.0 0.577
perf_LLC_store_misses: 1.6 0.516
perf_LLC_prefetch_misses: 9.0 14.742
+.fi
As we can notice, the load and store misses are relatively stable across runs
(their standard deviation is relatively low) compared to the prefetch misses.
accounted for quite precisely, but prefetches within a function seems to behave
too erratically (not much causality link between the code executed and the CPU
prefetch activity) to be accounted for.
-.fi
.B OPTIONS:
-.nf
-\-h, \-\-help
- Show summary of possible options and commands.
-\-k, \-\-kernel
- Apply for the kernel tracer
-\-u, \-\-userspace
- Apply for the user-space tracer
-\-\-function
- Dynamic function entry/return probe (default)
-.fi
-
-.IP
+.TP
+.BR "\-h, \-\-help"
+Show summary of possible options and commands.
+.TP
+.BR "\-k, \-\-kernel"
+Apply for the kernel tracer
+.TP
+.BR "\-u, \-\-userspace"
+Apply for the user-space tracer
+.TP
+.BR "\-\-function"
+Dynamic function entry/return probe (default)
+.RE
+.PP
.IP "\fBcreate\fP [NAME] [OPTIONS]
.nf
If no \fB\-o, \-\-output\fP is specified, the traces will be written in
$HOME/lttng-traces.
+
+The $HOME environment variable can be overridden by defining the environment
+variable LTTNG_HOME. This is useful when the user running the commands has
+a non-writeable home directory.
.fi
.B OPTIONS:
Simple listing of options
\-o, \-\-output PATH
Specify output path for traces
+\-\-no-output
+ Traces will not be outputed
+\-\-snapshot
+ Set the session in snapshot mode. Created in no-output mode
+ and uses the URL, if one, as the default snapshot output.
+ Every channel will be set in overwrite mode and with mmap
+ output (splice not supported).
Using these options, each API call can be controlled individually. For
instance, \-C does not enable the consumer automatically. You'll need the \-e
file.
It is important to note that if a certain type of buffers is used, the session
-will be set with that type and all other subsequent channel need to have the
+will be set with that type and all other subsequent channel needs to have the
same type.
+
+Note that once the session has been started and enabled on the tracer side,
+it's not possible anymore to enable a new channel for that session.
.fi
.B OPTIONS:
\-\-overwrite
Flight recorder mode : overwrites events when subbuffers are full
\-\-subbuf-size SIZE
- Subbuffer size in bytes (default: 4096, kernel default: 262144)
- Needs to be a power of 2 for both tracers
+ Subbuffer size in bytes {+k,+M,+G}
+ (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
+ Rounded up to the next power of 2.
+
+ The minimum subbuffer size, for each tracer, is the max value between
+ the default above and the system page size. You can issue this command
+ to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
\-\-num-subbuf NUM
- Number of subbuffers (default: 4)
- Needs to be a power of 2 for both tracers
+ Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4, metadata: 2)
+ Rounded up to the next power of 2.
\-\-switch-timer USEC
- Switch subbuffer timer interval in µsec (default: 0)
+ Switch subbuffer timer interval in µsec.
+ (default UST uid: 0, UST pid: 0, kernel: 0, metadata: 0)
\-\-read-timer USEC
- Read timer interval in µsec (default: 200)
+ Read timer interval in µsec.
+ (default UST uid: 0, UST pid: 0, kernel: 200000, metadata: 0)
\-\-output TYPE
Channel output type. Possible values: mmap, splice
+ (default UST uid: mmap, UST pid: mmap, kernel: splice, metadata: mmap)
\-\-buffers-uid
Use per UID buffer (\-u only). Buffers are shared between applications
that have the same UID.
Use per PID buffer (\-u only). Each application has its own buffers.
\-\-buffers-global
Use shared buffer for the whole system (\-k only)
+\-C, \-\-tracefile-size SIZE
+ Maximum size of each tracefile within a stream (in bytes).
+ 0 means unlimited. (default: 0)
+\-W, \-\-tracefile-count COUNT
+ Used in conjunction with \-C option, this will limit the number
+ of files created to the specified count. 0 means unlimited. (default: 0)
+
+.B EXAMPLES:
+
+$ lttng enable-channel -C 4096 -W 32 chan1
+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.
+
+ ~/lttng-traces/[...]/chan1_0_0 (4096)
+ ~/lttng-traces/[...]/chan1_0_1 (4096)
+ ~/lttng-traces/[...]/chan1_0_2 (3245)
+ ~/lttng-traces/[...]/chan1_1_0 (4096)
+ ...
+
+$ lttng enable-channel -C 4096
+This will create trace files of 4096 bytes and will create new ones as long as
+there is data available.
.fi
.IP
\-\-filter 'expression'
Set a filter on a newly enabled event. Filter expression on event
- fields, 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 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.
+ 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
+ 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.
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.
+ the '*' character, and '\\\\' for the '\\' character. Wildcard
+ match any sequence of characters, including an empty sub-string
+ (match 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 running applications can be found
+ under columns "PID" and "LWP" of the "ps -eLf" command.
+
+ '$ctx.procname == "demo*"'
+ '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
+ '$ctx.vtid == 1234'
.fi
.IP "\fBdisable-channel\fP NAME[,NAME2,...] [\-k|\-u] [OPTIONS]"
.IP
+.IP "\fBsnapshot\fP ACTION"
+.nf
+Snapshot command for LTTng session.
+.fi
+
+.B OPTIONS:
+
+.nf
+\-h, \-\-help
+ Show summary of possible options and commands.
+\-\-list-options
+ Simple listing of options
+.fi
+
+.B ACTION:
+
+.nf
+\fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
+
+Setup and add an snapshot output for a session. Output are the destination
+where the snapshot will be sent. Only one output is permitted. To change it,
+you'll need to delete it and add back the new one.
+
+\fBdel-output\fP ID | NAME [-s <NAME>]
+
+Delete an output for a session using the ID. You can either specify the
+output's ID that can be found with list-output or the name.
+
+\fBlist-output\fP [-s <NAME>]
+
+List the output of a session. Attributes of the output are printed.
+
+\fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
+
+Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
+used instead of a previously added output. Specifying only a name or/and a max
+size will override the current output values. For instance, you can record a
+snapshot with a custom maximum size or with a different name.
+
+$ lttng add-output -n mysnapshot file:///data/snapshot
+[...]
+$ lttng snapshot record -n new_name_snapshot
+
+The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
+rather then in mysnapshot*/
+.fi
+
+.B LONG OPTIONS
+
+.nf
+\-s, \-\-session NAME
+ Apply to session name.
+\-n, \-\-name NAME
+ Name of the snapshot's output.
+\-m, \-\-max-size SIZE
+ Maximum size in bytes of the snapshot. The maxium size does not
+ include the metadata file.
+\-C, \-\-ctrl-url URL
+ Set control path URL. (Must use -D also)
+\-D, \-\-data-url URL
+ Set data path URL. (Must use -C also)
+.fi
+
+.IP
+
.IP "\fBstart\fP [NAME] [OPTIONS]"
.nf
Start tracing
projects / lttng-tools.git / blobdiff