# Yocto Project Profiling and Tracing Manual

## Introduction

Yocto bundles a number of tracing and profiling tools - this 'HOWTO' describes their basic usage and shows by example how to make use of them to examine application and system behavior.

The tools presented are for the most part completely open-ended and have quite good and/or extensive documentation of their own which can be used to solve just about any problem you might come across in Linux. Each section that describes a particular tool has links to that tool's documentation and website.

The purpose of this 'HOWTO' is to present a set of common and generally useful tracing and profiling idioms along with their application (as appropriate) to each tool, in the context of a general-purpose 'drill-down' methodology that can be applied to solving a large number (90%?) of problems. For help with more advanced usages and problems, please see the documentation and/or websites listed for each tool.

The final section of this 'HOWTO' is a collection of real-world examples which we'll be continually adding to as we solve more problems using the tools - feel free to add your own examples to the list!

## General Setup

Most of the tools are available only in 'sdk' images or in images built after adding 'tools-profile' to your local.conf. So, in order to be able to access all of the tools described here, please first build and boot an 'sdk' image e.g.

         $ bitbake core-image-sato-sdk

or alternatively by adding 'tools-profile' to the EXTRA_IMAGE_FEATURES line in your local.conf:

          EXTRA_IMAGE_FEATURES = "debug-tweaks tools-profile"

If you use the 'tools-profile' method, you don't need to build an sdk image - the tracing and profiling tools will be included in non-sdk images as well e.g.:

         $ bitbake core-image-sato

By default, the Yocto build system strips symbols from the binaries it packages, which makes it difficult to use some of the tools.

You can prevent that by setting the `INHIBIT_PACKAGE_STRIP` variable to "1" in your `local.conf` when you build the image:

         INHIBIT_PACKAGE_STRIP = "1"

The above setting will noticeably increase the size of your image.

If you've already built a stripped image, you can generate debug packages (xxx-dbg) which you can manually install as needed.

To generate debug info for packages, you can add dbg-pkgs to EXTRA_IMAGE_FEATURES in local.conf. For example:

         EXTRA_IMAGE_FEATURES = "debug-tweaks tools-profile dbg-pkgs"

Additionally, in order to generate the right type of debuginfo, we also need to add the following to local.conf:

         PACKAGE_DEBUG_SPLIT_STYLE = 'debug-file-directory'