Configuration tips for building Linux real-time applications using CMake

Configuration tips for building Linux real-time applications using CMake

Introduction:
As the demand for real-time computing increases, the need to build real-time applications is also increasing. CMake is a popular cross-platform build tool that provides rich configuration options and easy-to-use syntax to help developers efficiently build real-time applications. This article will introduce some configuration tips for using CMake to build Linux real-time applications and provide relevant code examples.

1. Configure the CMakeLists.txt file
Before starting to build a Linux real-time application, we need to configure the CMakeLists.txt file. CMakeLists.txt is the CMake build script used to specify the build information and dependencies of the project.

First, we need to add the following lines in the CMakeLists.txt file to enable the C99 standard and use the RT (Real-Time) library:

set(CMAKE_C_STANDARD 99)
set(CMAKE_C_STANDARD_REQUIRED ON)

find_library(RT_LIBRARY rt)

Then, we can specify the name of the project, Source and target executables:

cmake_minimum_required(VERSION 3.12)

project(realtime_app)

set(SOURCE_FILES main.c)

add_executable(realtime_app ${SOURCE_FILES})

Next, we need to specify the other dependencies required by the real-time application. For example, if we need to use the POSIX thread library, we can add the following line:

find_package(Threads REQUIRED)

Then, we can add it to the target executable file:

target_link_libraries(realtime_app ${RT_LIBRARY} Threads::Threads)

2. Configure the real-time scheduling policy
In Linux, we can use the sched_setscheduler function to select a real-time scheduling strategy. In the CMakeLists.txt file, we can add the following code to set the real-time scheduling policy:

target_link_libraries(realtime_app ${RT_LIBRARY} Threads::Threads)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_GNU_SOURCE")
target_compile_definitions(realtime_app PRIVATE _GNU_SOURCE)

Then, we can use the sched_setscheduler function in the code to set the real-time scheduling policy:

#include <sched.h>

struct sched_param params;
params.sched_priority = sched_get_priority_max(SCHED_FIFO);
sched_setscheduler(0, SCHED_FIFO, &params);

3. Configuring the real-time clock
In order to obtain higher time resolution and accuracy, we can use a clock based on real time. In the CMakeLists.txt file, we can add the following code to configure the real-time clock:

target_link_libraries(realtime_app ${RT_LIBRARY} Threads::Threads)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_GNU_SOURCE")
target_compile_definitions(realtime_app PRIVATE _GNU_SOURCE)

find_library(REALTIME_LIBRARY rt)

Then, we can add the real-time clock library to the target executable:

target_link_libraries(realtime_app ${RT_LIBRARY} ${REALTIME_LIBRARY} Threads::Threads)

Next, We can use the clock_nanosleep function in the code to use the real-time clock:

#include <time.h>

struct timespec sleep_time;
sleep_time.tv_sec = 0;
sleep_time.tv_nsec = 1000000; // 1 millisecond
clock_nanosleep(CLOCK_REALTIME, 0, &sleep_time, NULL);

Conclusion:
This article introduces the configuration skills of using CMake to build Linux real-time applications and provides relevant code examples. By configuring the CMakeLists.txt file, selecting a real-time scheduling strategy and configuring the real-time clock, we can provide better performance and accuracy for real-time applications. I hope this article can help developers better build real-time applications and achieve efficient processing of real-time computing needs.

Reference:

1. "CMake 3.12 Documentation" [Online]. Available: https://cmake.org/documentation/
2. "POSIX Threads Programming" [Online]. Available: http://man7.org/linux/man-pages/man7/pthreads.7.html
3. "Linux Scheduler" [Online]. Available: http://man7.org /linux/man-pages/man7/sched.7.html
4. "Real-time Clocks" [Online]. Available: http://man7.org/linux/man-pages/man7/clock_gettime. 7.html

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