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

Introducing perf

perf is an abbreviation of the Linux performance event counter subsystem, perf_events, and also the name of the command-line tool for interacting with perf_events. Both have been part of the kernel since Linux 2.6.31. There is plenty of useful information in the Linux source tree in tools/perf/Documentation, and also at https://perf.wiki.kernel.org.

The initial impetus for developing perf was to provide a unified way to access the registers of the performance measurement unit (PMU), which is part of most modern processor cores. Once the API was defined and integrated into Linux, it became logical to extend it to cover other types of performance counters.

At its heart, perf is a collection of event counters with rules about when they actively collect data. By setting the rules, you can capture data from the whole system, or just the kernel, or just one process and its children, and do it across all CPUs or just one CPU. It is very flexible. With this one tool you can start...