Book Image

Mastering Embedded Linux Programming - Second Edition

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming - Second Edition

By: Chris Simmonds

Overview of this book

Embedded Linux runs many of the devices we use every day, from smart TVs to WiFi routers, test equipment to industrial controllers - all of them have Linux at their heart. Linux is a core technology in the implementation of the inter-connected world of the Internet of Things. The comprehensive guide shows you the technologies and techniques required to build Linux into embedded systems. You will begin by learning about the fundamental elements that underpin all embedded Linux projects: the toolchain, the bootloader, the kernel, and the root filesystem. You’ll see how to create each of these elements from scratch, and how to automate the process using Buildroot and the Yocto Project. Moving on, you’ll find out how to implement an effective storage strategy for flash memory chips, and how to install updates to the device remotely once it is deployed. You’ll also get to know the key aspects of writing code for embedded Linux, such as how to access hardware from applications, the implications of writing multi-threaded code, and techniques to manage memory in an efficient way. The final chapters show you how to debug your code, both in applications and in the Linux kernel, and how to profile the system so that you can look out for performance bottlenecks. By the end of the book, you will have a complete overview of the steps required to create a successful embedded Linux system.
Table of Contents (17 chapters)

Poor man's profiler

You can profile an application just by using GDB to stop it at arbitrary intervals to see what it is doing. This is the poor man's profiler. It is easy to set up and is one way of gathering profile data.

The procedure is simple:

  1. Attach to the process using gdbserver (for a remote debug) or GDB (for a native debug). The process stops.
  2. Observe the function it stopped in. You can use the backtrace GDB command to see the call stack.
  3. Type continue so that the program resumes.
  4. After a while, type Ctrl + C to stop it again, and go back to step 2.

If you repeat steps 2 to 4 several times, you will quickly get an idea of whether it is looping or making progress, and if you repeat them often enough, you will get an idea of where the hot spots in the code are.

There is a whole web page dedicated to the idea at http://poormansprofiler.org, together with scripts...