Using LTTng

LTTng is a set of dual licensed GPLv2 and LGPL tracing and profiling tools for both applications and kernel. It produces binary trace files in the production optimized Compact Trace Format (CTF), which can then be analyzed by tools, such as babeltrace.

Getting ready

To include the different LTTng tools in your system, add the following to your conf/local.conf file:

IMAGE_INSTALL_append = " lttng-tools lttng-modules lttng-ust"

They are also part of the tools-profile image feature, so you can also add them with:

EXTRA_IMAGE_FEATURES += "tools-profile"

These are also included in the -sdk images.

Tip

At the time of writing, Yocto 1.7 excludes lttng-modules from the tools-profile feature and sdk images for ARM; so they have to be added manually.

The LTTng command-line tool is the main user interface to LTTng. It can be used to trace both the Linux kernel—using the kernel tracing interfaces we have seen in previous recipes—as well as instrumented user space applications.

How to do it...

A kernel...