Book Image

Mastering Embedded Linux Programming

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming

By: Chris Simmonds

Overview of this book

Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will begin by learning about toolchains, bootloaders, the Linux kernel, and how to configure a root filesystem to create a basic working device. You will then learn how to use the two most commonly used build systems, Buildroot and Yocto, to speed up and simplify the development process. Building on this solid base, the next section considers how to make best use of raw NAND/NOR flash memory and managed flash eMMC chips, including mechanisms for increasing the lifetime of the devices and to perform reliable in-field updates. Next, you need to consider what techniques are best suited to writing applications for your device. We will then see how functions are split between processes and the usage of POSIX threads, which have a big impact on the responsiveness and performance of the final device The closing sections look at the techniques available to developers for profiling and tracing applications and kernel code using perf and ftrace.
Table of Contents (16 chapters)
15
Index

Identifying memory leaks

A memory leak occurs when memory is allocated but not freed when it is no longer needed. Memory leakage is by no means unique to embedded systems, but it becomes an issue partly because targets don't have much memory in the first place, and partly because they often run for long periods of time without rebooting, allowing the leaks to become a large puddle.

You will realize that there is a leak when you run free or top and see that free memory is continually going down, even if you drop caches, as shown in the preceding section. You will be able to identify the culprit (or culprits) by looking at the Uss and Rss per process.

There are several tools for identifying memory leaks in a program. I will look at two: mtrace and Valgrind.

mtrace

mtrace is a component of glibc that traces calls to malloc(3), free(3), and related functions, and identifies areas of memory not freed when the program exits. You need to call the mtrace() function from within the program to begin...