The LTTng analyses are a set of various executable analyses to extract and visualize monitoring data and metrics from LTTng kernel traces on the command line.
As opposed to other "live" diagnostic or monitoring solutions, this approach is based on the following workflow:
- Record your system's activity with LTTng, a low-overhead tracer.
- Do whatever it takes for your problem to occur.
- Diagnose your problem's cause offline (when tracing is stopped).
This solution allows you to target problems that are hard to find and to "dig" until the root cause is found.
Current limitations:
The LTTng analyses can be quite slow to execute. There are a number of places where they could be optimized, but using the Python interpreter seems to be an important impediment.
This project is regarded by its authors as a testing ground to experiment analysis features, user interfaces, and usability in general. It is not considered ready to analyze long traces.
Contents:
- Python ≥ 3.4
- setuptools
- pyparsing ≥ 2.0.0
- Babeltrace ≥ 1.2 with Python
bindings (
--enable-python-bindingswhen building from source)
- LTTng ≥ 2.5: to use the
lttng-analyses-recordscript and to trace the system in general - termcolor: color support
- progressbar: terminal progress bar support (this is not required for the machine interface's progress indication feature)
To install the latest LTTng analyses release on your system from PyPI:
Install the required dependencies.
Optional: Install the optional dependencies.
Make sure
pipfor Python 3 is installed on your system. The package is namedpython3-pipon most distributions (python-pipon Arch Linux).Use
pip3to install LTTng analyses:sudo pip3 install --upgrade lttnganalyses
Note that you can also install LTTng analyses locally, only for your user:
pip3 install --user --upgrade lttnganalyses
Files are installed in
~/.local, therefore~/.local/binmust be part of yourPATHenvironment variable for the LTTng analyses to be launchable.
To install a specific LTTng analyses release (tarball) on your system:
Install the required dependencies.
Optional: Install the optional dependencies.
Download and extract the desired release tarball.
Use
setup.pyto install LTTng analyses:sudo ./setup.py install
To install LTTng analyses from a specific branch or tag of the project's Git repository:
Install the required dependencies.
Optional: Install the optional dependencies.
Make sure
pipfor Python 3 is installed on your system. The package is namedpython3-pipon most distributions (python-pipon Arch Linux).Use
pip3to install LTTng analyses:sudo pip3 install --upgrade git+git://github.com/lttng/lttng-analyses.git@master
Replace
masterwith the desired branch or tag name to install in the previous URL.Note that you can also install LTTng analyses locally, only for your user:
sudo pip3 install --user --upgrade git+git://github.com/lttng/lttng-analyses.git@master
Files are installed in
~/.local, therefore~/.local/binmust be part of yourPATHenvironment variable for the LTTng analyses to be launchable.
To install LTTng analyses on Ubuntu ≥ 12.04:
Add the LTTng Latest Stable PPA repository:
sudo apt-get install -y software-properties-common sudo apt-add-repository -y ppa:lttng/ppa sudo apt-get update
Replace
software-properties-commonwithpython-software-propertieson Ubuntu 12.04.Install the required dependencies:
sudo apt-get install -y babeltrace sudo apt-get install -y python3-babeltrace sudo apt-get install -y python3-setuptools
On Ubuntu > 12.04:
sudo apt-get install -y python3-pyparsing
On Ubuntu 12.04:
sudo pip3 install --upgrade pyparsing
Optional: Install the optional dependencies:
sudo apt-get install -y lttng-tools sudo apt-get install -y lttng-modules-dkms sudo apt-get install -y python3-progressbar sudo apt-get install -y python3-termcolor
Install LTTng analyses:
sudo apt-get install -y python3-lttnganalyses
To install LTTng analyses on Debian "sid":
Install the required dependencies:
sudo apt-get install -y babeltrace sudo apt-get install -y python3-babeltrace sudo apt-get install -y python3-setuptools sudo apt-get install -y python3-pyparsing
Optional: Install the optional dependencies:
sudo apt-get install -y lttng-tools sudo apt-get install -y lttng-modules-dkms sudo apt-get install -y python3-progressbar sudo apt-get install -y python3-termcolor
Install LTTng analyses:
sudo apt-get install -y python3-lttnganalyses
If you just want to try the tools, a sample trace is available here.
If you want to see a step-by-step usage of these tools to identify a single unusual request latency, you can check this blog post, it shows how to navigate in the sample trace and accurately find the culprit.
This section is a quick reminder of how to record an LTTng kernel trace. See LTTng's quick start guide to familiarize with LTTng.
LTTng analyses ships with a handy (installed) script,
lttng-analyses-record, which automates
the steps to record a kernel trace with the events required by the
analyses.
To use lttng-analyses-record:
Launch the installed script:
lttng-analyses-record
Do whatever it takes for your problem to occur.
When you are done recording, press Ctrl+C where the script is running.
To record an LTTng kernel trace suitable for the LTTng analyses:
Create a tracing session:
sudo lttng create
Create a channel with a large sub-buffer size:
sudo lttng enable-channel --kernel chan --subbuf-size=8M
Create event rules to capture the needed events:
sudo lttng enable-event --kernel --channel=chan block_bio_backmerge sudo lttng enable-event --kernel --channel=chan block_bio_remap sudo lttng enable-event --kernel --channel=chan block_rq_complete sudo lttng enable-event --kernel --channel=chan block_rq_issue sudo lttng enable-event --kernel --channel=chan irq_handler_entry sudo lttng enable-event --kernel --channel=chan irq_handler_exit sudo lttng enable-event --kernel --channel=chan irq_softirq_entry sudo lttng enable-event --kernel --channel=chan irq_softirq_exit sudo lttng enable-event --kernel --channel=chan irq_softirq_raise sudo lttng enable-event --kernel --channel=chan kmem_mm_page_alloc sudo lttng enable-event --kernel --channel=chan kmem_mm_page_free sudo lttng enable-event --kernel --channel=chan lttng_statedump_block_device sudo lttng enable-event --kernel --channel=chan lttng_statedump_file_descriptor sudo lttng enable-event --kernel --channel=chan lttng_statedump_process_state sudo lttng enable-event --kernel --channel=chan mm_page_alloc sudo lttng enable-event --kernel --channel=chan mm_page_free sudo lttng enable-event --kernel --channel=chan net_dev_xmit sudo lttng enable-event --kernel --channel=chan netif_receive_skb sudo lttng enable-event --kernel --channel=chan sched_pi_setprio sudo lttng enable-event --kernel --channel=chan sched_process_exec sudo lttng enable-event --kernel --channel=chan sched_process_fork sudo lttng enable-event --kernel --channel=chan sched_switch sudo lttng enable-event --kernel --channel=chan sched_wakeup sudo lttng enable-event --kernel --channel=chan sched_waking sudo lttng enable-event --kernel --channel=chan softirq_entry sudo lttng enable-event --kernel --channel=chan softirq_exit sudo lttng enable-event --kernel --channel=chan softirq_raise sudo lttng enable-event --kernel --channel=chan --syscall --all
Start recording:
sudo lttng start
Do whatever it takes for your problem to occur.
Stop recording and destroy the tracing session to free its resources:
sudo lttng stop sudo lttng destroy
See the LTTng Documentation for other use cases, like sending the trace data over the network instead of recording trace files on the target's file system.
The LTTng analyses are a set of various command-line analyses. Each analysis accepts the path to a recorded trace (see Record a trace) as its argument, as well as various command-line options to control the analysis and its output.
Many command-line options are common to all the analyses, so that you can filter by timerange, process name, process ID, minimum and maximum values, and the rest. Also note that the reported timestamps can optionally be expressed in the GMT time zone.
Each analysis is installed as an executable starting with the
lttng- prefix.
| Command | Description |
|---|---|
lttng-cputop |
Per-TID, per-CPU, and total top CPU usage. |
lttng-iolatencyfreq |
I/O request latency distribution. |
lttng-iolatencystats |
Partition and system call latency statistics. |
lttng-iolatencytop |
Top system call latencies. |
lttng-iolog |
I/O operations log. |
lttng-iousagetop |
I/O usage top. |
lttng-irqfreq |
Interrupt handler duration frequency distribution. |
lttng-irqlog |
Interrupt log. |
lttng-irqstats |
Hardware and software interrupt statistics. |
lttng-memtop |
Per-TID top allocated/freed memory. |
lttng-schedfreq |
Scheduling latency frequency distribution. |
lttng-schedlog |
Scheduling top. |
lttng-schedstats |
Scheduling latency stats. |
lttng-schedtop |
Scheduling top. |
lttng-periodlog |
Period log. |
lttng-periodstats |
Period duration stats. |
lttng-periodtop |
Period duration top. |
lttng-periodfreq |
Period duration frequency distribution. |
lttng-syscallstats |
Per-TID and global system call statistics. |
Use the --help option of any command to list the descriptions
of the possible command-line options.
Note
You can set the LTTNG_ANALYSES_DEBUG environment variable to
1 when you launch an analysis to enable a debug output. You can
also use the general --debug option.
Depending on the analysis, filter options are available. The complete list of filter options is:
| Command-line option | Description |
|---|---|
--begin |
Trace time at which to begin the analysis. Format: |
--cpu |
Comma-delimited list of CPU IDs for which to display the results. |
--end |
Trace time at which to end the analysis. Format: |
--irq |
List of hardware IRQ numbers for which to display the results. |
--limit |
Maximum number of output rows per table. This option is useful
for "top" analyses, like lttng-cputop. |
--min |
Minimum duration (µs) to keep in results. |
--minsize |
Minimum I/O operation size (B) to keep in results. |
--max |
Maximum duration (µs) to keep in results. |
--maxsize |
Maximum I/O operation size (B) to keep in results. |
--procname |
Comma-delimited list of process names for which to display the results. |
--softirq |
List of software IRQ numbers for which to display the results. |
--tid |
Comma-delimited list of thread IDs for which to display the results. |
LTTng analyses feature a powerful "period engine". A period is an interval which begins and ends under specific conditions. When the analysis results are displayed, they are isolated for the periods that were opened and closed during the process.
A period can have a parent. If it's the case, then its parent needs to exist for the period to begin at all. This tree structure of periods is useful to keep a form of custom user state during the generic kernel analysis.
Attention!
The --period and --period-captures options's arguments
include characters that are considered special by most shells,
like $, *, and &.
Make sure to always single-quote those arguments when running the LTTng analyses on the command line.
You can define one or more periods on the command line, when launching
an analysis, with the --period option. This option's argument
accepts the following form (content within square brackets is optional):
[ NAME [ (PARENT) ] ] : BEGINEXPR [ : ENDEXPR ]
NAMEOptional name of the period definition. All periods opened from this definition have this name.
The syntax of this name is the same as a C identifier.
PARENTOptional name of a previously defined period which acts as the parent period definition of this definition.
NAMEmust be set forPARENTto be set.BEGINEXPR- Matching expression which a given event must match in order for an actual period to be instantiated by this definition.
ENDEXPRMatching expression which a given event must match in order for an instance of this definition to be closed.
If this part is omitted,
BEGINEXPRis used for the ending expression too.
A matching expression is a C-like logical expression. It supports
nesting expressions with ( and ), as well as the && (logical
AND), || (logical OR), and ! (logical NOT) operators. The
precedence of those operators is the same as in the C language.
The atomic operands in those logical expressions are comparisons. For the following comparison syntaxes, consider that:
EVTindicates an event source. The available event sources are:$evtCurrent event.
$begin.$evtIn
BEGINEXPR: current event (same as$evt).In
ENDEXPR: event which, for this period instance, was matched whenBEGINEXPRwas evaluated.$parent.$begin.$evtEvent which, for the parent period instance of this period instance, was matched when
BEGINEXPRof the parent was evaluated.
FIELDindicates an event field source. The available event field sources are:NAME(direct field name)Automatic scope: try to find the field named
NAMEin the dynamic scopes in this order:- Event payload
- Event context
- Event header
- Stream event context
- Packet context
- Packet header
$payload.NAMEEvent payload field named
NAME.$ctx.NAMEEvent context field named
NAME.$header.NAMEEvent header field named
NAME.$stream_ctx.NAMEStream event context field named
NAME.$pkt_ctx.NAMEPacket context field named
NAME.$pkt_header.NAMEPacket header field named
NAME.
VALUEindicates one of:A constant, decimal number. This can be an integer or a real number, positive or negative, and supports the
escientific notation.Examples:
23,-18.28,7.2e9.A double-quoted literal string.
"and\can be escaped with\.Examples:
"hello, world!","here's another \"quoted\" string".An event field, that is,
EVT.FIELD, considering the replacements described above.
NUMVALUEindicates one of:A constant, decimal number. This can be an integer or a real number, positive or negative, and supports the
escientific notation.Examples:
23,-18.28,7.2e9.An event field, that is,
EVT.FIELD, considering the replacements described above.
| Comparison syntax | Description |
|---|---|
|
Name matching:
|
|
Value matching:
|
In any case, if EVT.FIELD does not target an existing field, the
comparison including it fails. Also, string fields cannot be compared to
number values (constant or fields).
Create a period instance named
switchwhen:- The current event name is
sched_switch.
End this period instance when:
- The current event name is
sched_switch.
Period definition:
switch : $evt.$name == "sched_switch"
- The current event name is
Create a period instance named
switchwhen:- The current event name is
sched_switchAND - The current event's
next_tidfield is NOT equal to 0.
End this period instance when:
- The current event name is
sched_switchAND - The current event's
prev_tidfield is equal to thenext_tidfield of the matched event in the begin expression AND - The current event's
cpu_idfield is equal to thecpu_idfield of the matched event in the begin expression.
Period definition:
switch : $evt.$name == "sched_switch" && $evt.next_tid != 0 : $evt.$name == "sched_switch" && $evt.prev_tid == $begin.$evt.next_tid && $evt.cpu_id == $begin.$evt.cpu_id
- The current event name is
Create a period instance named
irqwhen:- A parent period instance named
switchis currently opened. - The current event name satisfies the
irq_*_entryglobbing pattern AND - The current event's
cpu_idfield is equal to thecpu_idfield of the matched event in the begin expression of the parent period instance.
End this period instance when:
- The current event name is
irq_handler_exitAND - The current event's
cpu_idfield is equal to thecpu_idfield of the matched event in the begin expression.
Period definition:
irq(switch) : $evt.$name =* "irq_*_entry" && $evt.cpu_id == $parent.$begin.$evt.cpu_id : $evt.$name == "irq_handler_exit" && $evt.cpu_id == $begin.$evt.cpu_id
- A parent period instance named
Create a period instance named
hellowhen:- The current event name satisfies the
hello*globbing pattern, but excludeshello world.
End this period instance when:
- The current event name is the same as the name of the matched event in the begin expression AND
- The current event's
theidheader field is lesser than or equal to 231.
Period definition:
hello : $evt.$name =* "hello*" && $evt.$name != "hello world" : $evt.$name == $begin.$evt.$name && $evt.$header.theid <= 231
- The current event name satisfies the
When a period instance begins or ends, the analysis can capture the current values of specific event fields and display them in its results.
You can set period captures with the --period-captures command-line
option. This option's argument accepts the following form
(content within square brackets is optional):
NAME : BEGINCAPTURES [ : ENDCAPTURES ]
NAMEName of period instances on which to apply those captures.
A
--periodoption in the same command line must define this name.BEGINCAPTURES- Comma-delimited list of event fields to capture when the beginning
expression of the period definition named
NAMEis matched. ENDCAPTURESComma-delimited list of event fields to capture when the ending expression of the period definition named
NAMEis matched.If this part is omitted, there are no end captures.
The format of BEGINCAPTURES and ENDCAPTURES is a comma-delimited
list of tokens having this format:
[ CAPTURENAME = ] EVT.FIELD
or:
[ CAPTURENAME = ] EVT.$name
CAPTURENAMECustom name for this capture. The syntax of this name is the same as a C identifier.
If this part is omitted, the literal expression used for
EVT.FIELDis used.EVTandFIELD- See Matching expression.
With lttng-periodlog, it is possible to see the list of periods in the
context of their parent. By specifying the --aggregate-by, the lines in
the log present on the same line the timerange of the period specified by
the --select argument at the timerange of the parent period that contains
it. In lttng-periodstats and lttng-periodfreq, these two flags are
used as filter to limit the output to only the relevant periods. If omitted,
all existing combinations of parent/child statistics and frequency
distributions are output.
When fields are captured during the period analyses, it is possible to compute the statistics and frequency distribution grouped by values of the these fields, instead of globally for the trace. The format is:
--group-by "PERIODNAME.CAPTURENAME[, PERIODNAME.CAPTURENAME]"
If multiple values are passed, the analysis outputs one list of tables (statistics and/or frequency distribution) for each unique combination of the field's values.
For example, if we track the open system call and we are interested in the
average duration of this call by filename, we only have to capture the filename
field and group the results by open.filename.
Begin captures only:
switch : $evt.next_tid, name = $evt.$name, msg_id = $parent.$begin.$evt.id
Begin and end captures:
hello : beginning = $evt.$ctx.begin_ts, $evt.received_bytes : $evt.send_bytes, $evt.$name, begin = $begin.$evt.$ctx.begin_ts end = $evt.$ctx.end_ts
Top scheduling latency (delay between sched_waking(tid=$TID) and sched_switch(next_tid=$TID))
with recording of the procname of the waker (dependant of the procname context in the trace),
priority and target CPU:
lttng-periodtop /path/to/trace \
--period 'wake : $evt.$name == "sched_waking" : $evt.$name == "sched_switch" && $evt.next_tid == $begin.$evt.$payload.tid' \
--period-capture 'wake : waker = $evt.procname, prio = $evt.prio : wakee = $evt.next_comm, cpu = $evt.cpu_id'Timerange: [2016-07-21 17:07:47.832234248, 2016-07-21 17:07:48.948152659]
Period top
Begin End Duration (us) Name Begin capture End capture
[17:07:47.835338581, 17:07:47.946834976] 111496.395 wake waker = lttng-consumerd wakee = kworker/0:2
prio = 20 cpu = 0
[17:07:47.850409057, 17:07:47.946829256] 96420.199 wake waker = swapper/2 wakee = migration/0
prio = -100 cpu = 0
[17:07:48.300313282, 17:07:48.300993892] 680.610 wake waker = Xorg wakee = ibus-ui-gtk3
prio = 20 cpu = 3
[17:07:48.300330060, 17:07:48.300920648] 590.588 wake waker = Xorg wakee = ibus-x11
prio = 20 cpu = 3
Log of all the IRQ handled while a user-space process was running, capture the procname of the process interrupted, the name and number of the IRQ:
lttng-periodlog /path/to/trace \
--period 'switch : $evt.$name == "sched_switch" && $evt.next_tid != 0 : $evt.$name == "sched_switch" && $evt.prev_tid == $begin.$evt.next_tid && $evt.cpu_id == $begin.$evt.cpu_id' \
--period 'irq(switch) : $evt.$name == "irq_handler_entry" && $evt.cpu_id == $parent.$begin.$evt.cpu_id : $evt.$name == "irq_handler_exit" && $evt.cpu_id == $begin.$evt.cpu_id' \
--period-capture 'irq : name = $evt.name, irq = $evt.irq, current = $parent.$begin.$evt.next_comm'Period log
Begin End Duration (us) Name Begin capture End capture
[10:58:26.169238875, 10:58:26.169244920] 6.045 switch
[10:58:26.169598385, 10:58:26.169602967] 4.582 irq name = ahci
irq = 41
current = lttng-consumerd
[10:58:26.169811553, 10:58:26.169816218] 4.665 irq name = ahci
irq = 41
current = lttng-consumerd
[10:58:26.170025600, 10:58:26.170030197] 4.597 irq name = ahci
irq = 41
current = lttng-consumerd
[10:58:26.169236842, 10:58:26.170105711] 868.869 switch
Log of all the open system call periods aggregated by the sched_switch in which they occurred:
lttng-periodlog /path/to/trace \
--period 'switch : $evt.$name == "sched_switch" : $evt.$name == "sched_switch" && $begin.$evt.next_tid == $evt.prev_tid && $begin.$evt.cpu_id == $evt.cpu_id' \
--period 'open(switch) : $evt.$name == "syscall_entry_open" && $parent.$begin.$evt.cpu_id == $evt.cpu_id : $evt.$name == "syscall_exit_open" && $begin.$evt.cpu_id == $evt.cpu_id' \
--period-captures 'switch : comm = $evt.next_comm, cpu = $evt.cpu_id, tid = $evt.next_tid' \
--period-captures 'open : filename = $evt.filename : fd = $evt.ret' \
--select open
--aggregate-by switchAggregated log
Aggregation of (open) by switch
Parent | | Durations (us) |
Begin End Duration (us) Name | Child name Count | Min Avg Max Stdev Runtime | Parent captures
[10:58:26.222823677, 10:58:26.224039381] 1215.704 switch | switch/open 3 | 7.517 9.548 11.248 1.887 28.644 | switch.comm = bash, switch.cpu = 3, switch.tid = 12420
[10:58:26.856224058, 10:58:26.856589867] 365.809 switch | switch/open 1 | 77.620 77.620 77.620 ? 77.620 | switch.comm = ntpd, switch.cpu = 0, switch.tid = 11132
[10:58:27.000068031, 10:58:27.000954859] 886.828 switch | switch/open 15 | 9.224 16.126 37.190 6.681 241.894 | switch.comm = irqbalance, switch.cpu = 0, switch.tid = 1656
[10:58:27.225474282, 10:58:27.229160014] 3685.732 switch | switch/open 22 | 5.797 6.767 9.308 0.972 148.881 | switch.comm = bash, switch.cpu = 1, switch.tid = 12421
Statistics about the memory allocation performed within an open system call
within a single sched_switch (no blocking or preemption):
lttng-periodstats /path/to/trace \
--period 'switch : $evt.$name == "sched_switch" : $evt.$name == "sched_switch" && $begin.$evt.next_tid == $evt.prev_tid && $begin.$evt.cpu_id == $evt.cpu_id' \
--period 'open(switch) : $evt.$name == "syscall_entry_open" && $parent.$begin.$evt.cpu_id == $evt.cpu_id : $evt.$name == "syscall_exit_open" && $begin.$evt.cpu_id == $evt.cpu_id' \
--period 'alloc(open) : $evt.$name == "kmem_cache_alloc" && $parent.$begin.$evt.cpu_id == $evt.cpu_id : $evt.$name == "kmem_cache_free" && $evt.ptr == $begin.$evt.ptr' \
--period-captures 'switch : comm = $evt.next_comm, cpu = $evt.cpu_id, tid = $evt.next_tid' \
--period-captures 'open : filename = $evt.filename : fd = $evt.ret' \
--period-captures 'alloc : ptr = $evt.ptr'Timerange: [2015-01-06 10:58:26.140545481, 2015-01-06 10:58:27.229358936]
Period tree:
switch
|-- open
|-- alloc
Period statistics (us)
Period Count Min Avg Max Stdev Runtime
switch 831 2.824 5233.363 172056.802 16197.531 4348924.614
switch/open 41 5.797 12.123 77.620 12.076 497.039
switch/open/alloc 44 1.152 10.277 74.476 11.582 452.175
Per-parent period duration statistics (us)
With active children
Period Parent Min Avg Max Stdev
switch/open switch 28.644 124.260 241.894 92.667
switch/open/alloc switch 24.036 113.044 229.713 87.827
switch/open/alloc switch/open 4.550 11.029 74.476 11.768
Per-parent duration ratio (%)
With active children
Period Parent Min Avg Max Stdev
switch/open switch 2 13.723 27 12.421
switch/open/alloc switch 1 12.901 25 12.041
switch/open/alloc switch/open 76 88.146 115 7.529
Per-parent period count statistics
With active children
Period Parent Min Avg Max Stdev
switch/open switch 1 10.250 22 9.979
switch/open/alloc switch 1 11.000 22 10.551
switch/open/alloc switch/open 1 1.073 2 0.264
Per-parent period duration statistics (us)
Globally
Period Parent Min Avg Max Stdev
switch/open switch 0.000 0.598 241.894 10.251
switch/open/alloc switch 0.000 0.544 229.713 9.443
switch/open/alloc switch/open 4.550 11.029 74.476 11.768
Per-parent duration ratio (%)
Globally
Period Parent Min Avg Max Stdev
switch/open switch 0 0.066 27 1.209
switch/open/alloc switch 0 0.062 25 1.150
switch/open/alloc switch/open 76 88.146 115 7.529
Per-parent period count statistics
Globally
Period Parent Min Avg Max Stdev
switch/open switch 0 0.049 22 0.929
switch/open/alloc switch 0 0.053 22 0.991
switch/open/alloc switch/open 1 1.073 2 0.264
These statistics can also be scoped by value of the FD returned by the open
system, by appending --group-by "open.fd" to the previous command line.
That way previous tables will be output for each value of FD returned, so it
is possible to observe the behaviour based on the parameters of a system call.
Using the lttng-periodfreq or the --freq parameter, these tables can
also be presented as frequency distributions.
If the progressbar optional dependency is installed, a progress bar is available to indicate the progress of the analysis.
By default, the progress bar is based on the current event's timestamp.
Progress options are:
| Command-line option | Description |
|---|---|
--no-progress |
Disable the progress bar. |
--progress-use-size |
Use the approximate event size instead of the current event's timestamp to estimate the progress value. |
If you want to display LTTng analyses results in a custom viewer,
you can use the JSON-based LTTng analyses machine interface (LAMI).
Each command in the previous table has its corresponding LAMI version
with the -mi suffix. For example, the LAMI version of
lttng-cputop is lttng-cputop-mi.
This version of LTTng analyses conforms to LAMI 1.0.
The LAMI output can be used in TraceCompass (>=2.1) to create graphs based on the output of the scripts.
This section shows a few examples of using some LTTng analyses.
lttng-iolatencystats /path/to/traceTimerange: [2015-01-06 10:58:26.140545481, 2015-01-06 10:58:27.229358936] Syscalls latency statistics (usec): Type Count Min Average Max Stdev ----------------------------------------------------------------------------------------- Open 45 5.562 13.835 77.683 15.263 Read 109 0.316 5.774 62.569 9.277 Write 101 0.256 7.060 48.531 8.555 Sync 207 19.384 40.664 160.188 21.201 Disk latency statistics (usec): Name Count Min Average Max Stdev ----------------------------------------------------------------------------------------- dm-0 108 0.001 0.004 0.007 1.306
lttng-iolatencyfreq /path/to/traceTimerange: [2015-01-06 10:58:26.140545481, 2015-01-06 10:58:27.229358936] Open latency distribution (usec) ############################################################################### 5.562 ███████████████████████████████████████████████████████████████████ 25 9.168 ██████████ 4 12.774 █████████████████████ 8 16.380 ████████ 3 19.986 █████ 2 23.592 0 27.198 0 30.804 0 34.410 ██ 1 38.016 0 41.623 0 45.229 0 48.835 0 52.441 0 56.047 0 59.653 0 63.259 0 66.865 0 70.471 0 74.077 █████ 2
lttng-iolatencytop /path/to/trace --limit=3 --minsize=2Checking the trace for lost events... Timerange: [2015-01-15 12:18:37.216484041, 2015-01-15 12:18:53.821580313] Top open syscall latencies (usec) Begin End Name Duration (usec) Size Proc PID Filename [12:18:50.432950815,12:18:50.870648568] open 437697.753 N/A apache2 31517 /var/lib/php5/sess_0ifir2hangm8ggaljdphl9o5b5 (fd=13) [12:18:52.946080165,12:18:52.946132278] open 52.113 N/A apache2 31588 /var/lib/php5/sess_mr9045p1k55vin1h0vg7rhgd63 (fd=13) [12:18:46.800846035,12:18:46.800874916] open 28.881 N/A apache2 31591 /var/lib/php5/sess_r7c12pccfvjtas15g3j69u14h0 (fd=13) [12:18:51.389797604,12:18:51.389824426] open 26.822 N/A apache2 31520 /var/lib/php5/sess_4sdb1rtjkhb78sabnoj8gpbl00 (fd=13) Top read syscall latencies (usec) Begin End Name Duration (usec) Size Proc PID Filename [12:18:37.256073107,12:18:37.256555967] read 482.860 7.00 B bash 10237 unknown (origin not found) (fd=3) [12:18:52.000209798,12:18:52.000252304] read 42.506 1.00 KB irqbalance 1337 /proc/interrupts (fd=3) [12:18:37.256559439,12:18:37.256601615] read 42.176 5.00 B bash 10237 unknown (origin not found) (fd=3) [12:18:42.000281918,12:18:42.000320016] read 38.098 1.00 KB irqbalance 1337 /proc/interrupts (fd=3) Top write syscall latencies (usec) Begin End Name Duration (usec) Size Proc PID Filename [12:18:49.913241516,12:18:49.915908862] write 2667.346 95.00 B apache2 31584 /var/log/apache2/access.log (fd=8) [12:18:37.472823631,12:18:37.472859836] writev 36.205 21.97 KB apache2 31544 unknown (origin not found) (fd=12) [12:18:37.991578372,12:18:37.991612724] writev 34.352 21.97 KB apache2 31589 unknown (origin not found) (fd=12) [12:18:39.547778549,12:18:39.547812515] writev 33.966 21.97 KB apache2 31584 unknown (origin not found) (fd=12) Top sync syscall latencies (usec) Begin End Name Duration (usec) Size Proc PID Filename [12:18:50.162776739,12:18:51.157522361] sync 994745.622 N/A sync 22791 None (fd=None) [12:18:37.227867532,12:18:37.232289687] sync_file_range 4422.155 N/A lttng-consumerd 19964 /home/julien/lttng-traces/analysis-20150115-120942/kernel/metadata (fd=32) [12:18:37.238076585,12:18:37.239012027] sync_file_range 935.442 N/A lttng-consumerd 19964 /home/julien/lttng-traces/analysis-20150115-120942/kernel/metadata (fd=32) [12:18:37.220974711,12:18:37.221647124] sync_file_range 672.413 N/A lttng-consumerd 19964 /home/julien/lttng-traces/analysis-20150115-120942/kernel/metadata (fd=32)
lttng-iolog /path/to/trace[10:58:26.221618530,10:58:26.221620659] write 2.129 8.00 B /usr/bin/x-term 11793 anon_inode:[eventfd] (fd=5) [10:58:26.221623609,10:58:26.221628055] read 4.446 50.00 B /usr/bin/x-term 11793 /dev/ptmx (fd=24) [10:58:26.221638929,10:58:26.221640008] write 1.079 8.00 B /usr/bin/x-term 11793 anon_inode:[eventfd] (fd=5) [10:58:26.221676232,10:58:26.221677385] read 1.153 8.00 B /usr/bin/x-term 11793 anon_inode:[eventfd] (fd=5) [10:58:26.223401804,10:58:26.223411683] open 9.879 N/A sleep 12420 /etc/ld.so.cache (fd=3) [10:58:26.223448060,10:58:26.223455577] open 7.517 N/A sleep 12420 /lib/x86_64-linux-gnu/libc.so.6 (fd=3) [10:58:26.223456522,10:58:26.223458898] read 2.376 832.00 B sleep 12420 /lib/x86_64-linux-gnu/libc.so.6 (fd=3) [10:58:26.223918068,10:58:26.223929316] open 11.248 N/A sleep 12420 (fd=3) [10:58:26.231881565,10:58:26.231895970] writev 14.405 16.00 B /usr/bin/x-term 11793 socket:[45650] (fd=4) [10:58:26.231979636,10:58:26.231988446] recvmsg 8.810 16.00 B Xorg 1827 socket:[47480] (fd=38)
lttng-iousagetop /path/to/traceTimerange: [2014-10-07 16:36:00.733214969, 2014-10-07 16:36:18.804584183]
Per-process I/O Read
###############################################################################
██████████████████████████████████████████████████ 16.00 MB lttng-consumerd (2619) 0 B file 4.00 B net 16.00 MB unknown
█████ 1.72 MB lttng-consumerd (2619) 0 B file 0 B net 1.72 MB unknown
█ 398.13 KB postgres (4219) 121.05 KB file 277.07 KB net 8.00 B unknown
256.09 KB postgres (1348) 0 B file 255.97 KB net 117.00 B unknown
204.81 KB postgres (4218) 204.81 KB file 0 B net 0 B unknown
123.77 KB postgres (4220) 117.50 KB file 6.26 KB net 8.00 B unknown
Per-process I/O Write
###############################################################################
██████████████████████████████████████████████████ 16.00 MB lttng-consumerd (2619) 0 B file 8.00 MB net 8.00 MB unknown
██████ 2.20 MB postgres (4219) 2.00 MB file 202.23 KB net 0 B unknown
█████ 1.73 MB lttng-consumerd (2619) 0 B file 887.73 KB net 882.58 KB unknown
██ 726.33 KB postgres (1165) 8.00 KB file 6.33 KB net 712.00 KB unknown
158.69 KB postgres (1168) 158.69 KB file 0 B net 0 B unknown
80.66 KB postgres (1348) 0 B file 80.66 KB net 0 B unknown
Files Read
###############################################################################
██████████████████████████████████████████████████ 8.00 MB anon_inode:[lttng_stream] (lttng-consumerd) 'fd 32 in lttng-consumerd (2619)'
█████ 834.41 KB base/16384/pg_internal.init 'fd 7 in postgres (4219)', 'fd 7 in postgres (4220)', 'fd 7 in postgres (4221)', 'fd 7 in postgres (4222)', 'fd 7 in postgres (4223)', 'fd 7 in postgres (4224)', 'fd 7 in postgres (4225)', 'fd 7 in postgres (4226)'
█ 256.09 KB socket:[8893] (postgres) 'fd 9 in postgres (1348)'
█ 174.69 KB pg_stat_tmp/pgstat.stat 'fd 9 in postgres (4218)', 'fd 9 in postgres (1167)'
109.48 KB global/pg_internal.init 'fd 7 in postgres (4218)', 'fd 7 in postgres (4219)', 'fd 7 in postgres (4220)', 'fd 7 in postgres (4221)', 'fd 7 in postgres (4222)', 'fd 7 in postgres (4223)', 'fd 7 in postgres (4224)', 'fd 7 in postgres (4225)', 'fd 7 in postgres (4226)'
104.30 KB base/11951/pg_internal.init 'fd 7 in postgres (4218)'
12.85 KB socket (lttng-sessiond) 'fd 30 in lttng-sessiond (384)'
4.50 KB global/pg_filenode.map 'fd 7 in postgres (4218)', 'fd 7 in postgres (4219)', 'fd 7 in postgres (4220)', 'fd 7 in postgres (4221)', 'fd 7 in postgres (4222)', 'fd 7 in postgres (4223)', 'fd 7 in postgres (4224)', 'fd 7 in postgres (4225)', 'fd 7 in postgres (4226)'
4.16 KB socket (postgres) 'fd 9 in postgres (4226)'
4.00 KB /proc/interrupts 'fd 3 in irqbalance (1104)'
Files Write
###############################################################################
██████████████████████████████████████████████████ 8.00 MB socket:[56371] (lttng-consumerd) 'fd 30 in lttng-consumerd (2619)'
█████████████████████████████████████████████████ 8.00 MB pipe:[53306] (lttng-consumerd) 'fd 12 in lttng-consumerd (2619)'
██████████ 1.76 MB pg_xlog/00000001000000000000000B 'fd 31 in postgres (4219)'
█████ 887.82 KB socket:[56369] (lttng-consumerd) 'fd 26 in lttng-consumerd (2619)'
█████ 882.58 KB pipe:[53309] (lttng-consumerd) 'fd 18 in lttng-consumerd (2619)'
160.00 KB /var/lib/postgresql/9.1/main/base/16384/16602 'fd 14 in postgres (1165)'
158.69 KB pg_stat_tmp/pgstat.tmp 'fd 3 in postgres (1168)'
144.00 KB /var/lib/postgresql/9.1/main/base/16384/16613 'fd 12 in postgres (1165)'
88.00 KB /var/lib/postgresql/9.1/main/base/16384/16609 'fd 11 in postgres (1165)'
78.28 KB socket:[8893] (postgres) 'fd 9 in postgres (1348)'
Block I/O Read
###############################################################################
Block I/O Write
###############################################################################
██████████████████████████████████████████████████ 1.76 MB postgres (pid=4219)
████ 160.00 KB postgres (pid=1168)
██ 100.00 KB kworker/u8:0 (pid=1540)
██ 96.00 KB jbd2/vda1-8 (pid=257)
█ 40.00 KB postgres (pid=1166)
8.00 KB kworker/u9:0 (pid=4197)
4.00 KB kworker/u9:2 (pid=1381)
Disk nr_sector
###############################################################################
███████████████████████████████████████████████████████████████████ 4416.00 sectors vda1
Disk nr_requests
###############################################################################
████████████████████████████████████████████████████████████████████ 177.00 requests vda1
Disk request time/sector
###############################################################################
██████████████████████████████████████████████████████████████████ 0.01 ms vda1
Network recv_bytes
###############################################################################
███████████████████████████████████████████████████████ 739.50 KB eth0
█████ 80.27 KB lo
Network sent_bytes
###############################################################################
████████████████████████████████████████████████████████ 9.36 MB eth0
lttng-syscallstats /path/to/traceTimerange: [2015-01-15 12:18:37.216484041, 2015-01-15 12:18:53.821580313]
Per-TID syscalls statistics (usec)
find (22785) Count Min Average Max Stdev Return values
- getdents 14240 0.380 364.301 43372.450 1629.390 {'success': 14240}
- close 14236 0.233 0.506 4.932 0.217 {'success': 14236}
- fchdir 14231 0.252 0.407 5.769 0.117 {'success': 14231}
- open 7123 0.779 2.321 12.697 0.936 {'success': 7119, 'ENOENT': 4}
- newfstatat 7118 1.457 143.562 28103.532 1410.281 {'success': 7118}
- openat 7118 1.525 2.411 9.107 0.771 {'success': 7118}
- newfstat 7117 0.272 0.654 8.707 0.248 {'success': 7117}
- write 573 0.298 0.715 8.584 0.391 {'success': 573}
- brk 27 0.615 5.768 30.792 7.830 {'success': 27}
- rt_sigaction 22 0.227 0.283 0.589 0.098 {'success': 22}
- mmap 12 1.116 2.116 3.597 0.762 {'success': 12}
- mprotect 6 1.185 2.235 3.923 1.148 {'success': 6}
- read 5 0.925 2.101 6.300 2.351 {'success': 5}
- ioctl 4 0.342 1.151 2.280 0.873 {'success': 2, 'ENOTTY': 2}
- access 4 1.166 2.530 4.202 1.527 {'ENOENT': 4}
- rt_sigprocmask 3 0.325 0.570 0.979 0.357 {'success': 3}
- dup2 2 0.250 0.562 0.874 ? {'success': 2}
- munmap 2 3.006 5.399 7.792 ? {'success': 2}
- execve 1 7277.974 7277.974 7277.974 ? {'success': 1}
- setpgid 1 0.945 0.945 0.945 ? {'success': 1}
- fcntl 1 ? 0.000 0.000 ? {}
- newuname 1 1.240 1.240 1.240 ? {'success': 1}
Total: 71847
-----------------------------------------------------------------------------------------------------------------
apache2 (31517) Count Min Average Max Stdev Return values
- fcntl 192 ? 0.000 0.000 ? {}
- newfstat 156 0.237 0.484 1.102 0.222 {'success': 156}
- read 144 0.307 1.602 16.307 1.698 {'success': 117, 'EAGAIN': 27}
- access 96 0.705 1.580 3.364 0.670 {'success': 12, 'ENOENT': 84}
- newlstat 84 0.459 0.738 1.456 0.186 {'success': 63, 'ENOENT': 21}
- newstat 74 0.735 2.266 11.212 1.772 {'success': 50, 'ENOENT': 24}
- lseek 72 0.317 0.522 0.915 0.112 {'success': 72}
- close 39 0.471 0.615 0.867 0.069 {'success': 39}
- open 36 2.219 12162.689 437697.753 72948.868 {'success': 36}
- getcwd 28 0.287 0.701 1.331 0.277 {'success': 28}
- poll 27 1.080 1139.669 2851.163 856.723 {'success': 27}
- times 24 0.765 0.956 1.327 0.107 {'success': 24}
- setitimer 24 0.499 5.848 16.668 4.041 {'success': 24}
- write 24 5.467 6.784 16.827 2.459 {'success': 24}
- writev 24 10.241 17.645 29.817 5.116 {'success': 24}
- mmap 15 3.060 3.482 4.406 0.317 {'success': 15}
- munmap 15 2.944 3.502 4.154 0.427 {'success': 15}
- brk 12 0.738 4.579 13.795 4.437 {'success': 12}
- chdir 12 0.989 1.600 2.353 0.385 {'success': 12}
- flock 6 0.906 1.282 2.043 0.423 {'success': 6}
- rt_sigaction 6 0.530 0.725 1.123 0.217 {'success': 6}
- pwrite64 6 1.262 1.430 1.692 0.143 {'success': 6}
- rt_sigprocmask 6 0.539 0.650 0.976 0.162 {'success': 6}
- shutdown 3 7.323 8.487 10.281 1.576 {'success': 3}
- getsockname 3 1.015 1.228 1.585 0.311 {'success': 3}
- accept4 3 5174453.611 3450157.282 5176018.235 ? {'success': 2}
Total: 1131
lttng-irqstats /path/to/traceTimerange: [2014-03-11 16:05:41.314824752, 2014-03-11 16:05:45.041994298]
Hard IRQ Duration (us)
count min avg max stdev
----------------------------------------------------------------------------------|
1: <i8042> 30 10.901 45.500 64.510 18.447 |
42: <ahci> 259 3.203 7.863 21.426 3.183 |
43: <eth0> 2 3.859 3.976 4.093 0.165 |
44: <iwlwifi> 92 0.300 3.995 6.542 2.181 |
Soft IRQ Duration (us) Raise latency (us)
count min avg max stdev | count min avg max stdev
----------------------------------------------------------------------------------|------------------------------------------------------------
1: <TIMER_SOFTIRQ> 495 0.202 21.058 51.060 11.047 | 53 2.141 11.217 20.005 7.233
3: <NET_RX_SOFTIRQ> 14 0.133 9.177 32.774 10.483 | 14 0.763 3.703 10.902 3.448
4: <BLOCK_SOFTIRQ> 257 5.981 29.064 125.862 15.891 | 257 0.891 3.104 15.054 2.046
6: <TASKLET_SOFTIRQ> 26 0.309 1.198 1.748 0.329 | 26 9.636 39.222 51.430 11.246
7: <SCHED_SOFTIRQ> 299 1.185 14.768 90.465 15.992 | 298 1.286 31.387 61.700 11.866
9: <RCU_SOFTIRQ> 338 0.592 3.387 13.745 1.356 | 147 2.480 29.299 64.453 14.286
lttng-irqfreq --timerange=[16:05:42,16:05:45] --irq=44 --stats /path/to/traceTimerange: [2014-03-11 16:05:42.042034570, 2014-03-11 16:05:44.998914297]
Hard IRQ Duration (us)
count min avg max stdev
----------------------------------------------------------------------------------|
44: <iwlwifi> 72 0.300 4.018 6.542 2.164 |
Frequency distribution iwlwifi (44)
###############################################################################
0.300 █████ 1.00
0.612 ██████████████████████████████████████████████████████████████ 12.00
0.924 ████████████████████ 4.00
1.236 ██████████ 2.00
1.548 0.00
1.861 █████ 1.00
2.173 0.00
2.485 █████ 1.00
2.797 ██████████████████████████ 5.00
3.109 █████ 1.00
3.421 ███████████████ 3.00
3.733 0.00
4.045 █████ 1.00
4.357 █████ 1.00
4.669 ██████████ 2.00
4.981 ██████████ 2.00
5.294 █████████████████████████████████████████ 8.00
5.606 ████████████████████████████████████████████████████████████████████ 13.00
5.918 ██████████████████████████████████████████████████████████████ 12.00
6.230 ███████████████ 3.00
LTTng analyses is part of the LTTng project and shares its community.
We hope you have fun trying this project and please remember it is a work in progress; feedback, bug reports and improvement ideas are always welcome!
| Item | Location | Notes |
|---|---|---|
| Mailing list | lttng-dev
([email protected]) |
Preferably, use the [lttng-analyses] subject prefix |
| IRC | #lttng on the OFTC network |
|
| Code contribution | Create a new GitHub pull request | |
| Bug reporting | Create a new GitHub issue | |
| Continuous integration | lttng-analyses_master_build item on LTTng's CI and lttng/lttng-analyses project on Travis CI | |
| Blog | The LTTng blog contains some posts about LTTng analyses |