---
name: "lttngtop"
section: "1"
platform: "linux"
package: "lttngtop"
version: "0.2-2+b1"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/lttngtop"
---

# lttngtop(1)

LTTng Trace Viewer

## NAME

lttngtop — LTTng Trace Viewer

## SYNOPSIS

```
lttngtop INPUT
```

## DESCRIPTION

Lttngtop is a ncurses interface for reading and browsing traces recorded by the LTTng tracer and displaying various statistics. As of now, the cpu usage, performance counters and per process/file I/O bandwidth are displayed. This version currently only supports offline traces, but a live version is in alpha and will be available for testing soon.

## OPTIONS

- **INPUT**

  Input trace path

## TRACE REQUIREMENTS

LTTngTop requires that the pid, procname, tid and ppid context information are enabled during tracing.

If you want the CPU activity view, you need the sched\_switch event, if you want the I/O statistics, you need to enable the system call tracing, and if you want the performance counters, you need to enable them for the events you are interested in (or all of them). Note, there is a hardware limitation for the number of performance counter you can enable, check dmesg for information.

The following example creates a trace with all events enabled, the mandatory context informations and three performance counters. It assumes that you are running as root or with a user part of the tracing group and a lttng-sessiond launched as root.

```
lttng create lttngtop
lttng enable-event -k -a
lttng add-context -k -t pid -t procname -t tid -t ppid -t perf:cache-misses -t perf:major-faults -t perf:branch-load-misses
lttng start
sleep 10
lttng stop
lttng destroy
```

## KEY BINDINGS

- ´**F2**´: *CPUTop*

  Switch to the CPUTop view which displays the CPU usage of each process

- ´**F3**´: *PerfTop*

  Switch to the PerfTop view which displays the performance counters (PMU) value of each process (if enabled during tracing)

- ´**F4**´: *IOTop*

  Switch to the IOTop view which displays the I/O usage of each process (as of now read and writes on any file descriptor network or disk)

- ´**Enter**´: *Process details*

  Display all relevant information for the process selected

- ´**Space**´: *Highlight*

  Highlights the process under the blue line to make it easy to find it across all views or toggle view in preference panel

- ´**q**´: *Quit*

  Exit the program

- ´**t**´: *Threads*

  Toggle threads display in CPUTop

- ´**r**´: *Preferences*

  Display the preference menu for the current view, this menu helps select the column displayed (only in PerfTop view for now) and the column to sort, use 's' to sort and 'space' to toggle the view

- ´**s**´: *Sort*

  In preference view, sort on the currently selected line

- ´**p**´: *Pause/Resume*

  Pause the display, hit again to resume the refresh (only works when the trace has not been fully displayed)

- ´**Right arrow**´: *Move forward in time*

  Display the next second of data, can be hit several time to bypass the default 1 second refresh period to fast forward

- ´**Left arrow**´: *Move backward in time*

  Display the previous second of data, automatically switch to pause if not already enabled

- ´**Up arrow´ / ´k´**: *Move UP the cursor*

  Move up the blue line to select processes

- ´**Down arrow´ / ´j´**: *Move DOWN the cursor*

  Move down the blue line to select processes

- ´**\>**': *Sort the next column*

  Update the sorting to the next column

- ´**\<**': *Sort the previous column*

  Update the sorting to the previous column

## SEE ALSO

[babeltrace(1)](/babeltrace/1.md), [babeltrace-log(1)](/babeltrace-log/1.md), [lttng(1)](/lttng/1.md), [lttng-ust(3)](/lttng-ust/3.md), [lttng-sessiond(8)](/lttng-sessiond/8.md)

## BUGS

No knows bugs at this point.

If you encounter any issues or usability problem, please report it on our mailing list \<lttng-dev@lists.lttng.org\> to help improve this project.

## CREDITS

LTTngTop is distributed under the GPLv2 license. See the LICENSE file in the source tree for details.

A Web site is available at http://www.efficios.com/babeltrace for more information on Babeltrace and the Common Trace Format. See http://lttng.org for more information on the LTTng project.

Mailing list for support and development: \<lttng-dev@lists.lttng.org\>.

You can find us on IRC server irc.oftc.net (OFTC) in #lttng.

## AUTHORS

LTTngTop was originally written by Julien Desfossez, with contribution from Mathieu Bain for the I/O bandwidth view, and suggestions and ideas from the team working with the LTTng project. It is currently maintained by Julien Desfossez \<jdesfossez@efficios.com\>