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Table of contents
REAL TIME IN EMBEDDED LINUX SYSTEMS
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Contents
INTRODUCTION
Hard Real Time
Soft Real Time
Standard Linux and Real Time
LATENCY IN LINUX
Linux processes
Switching processes
Linux kernel latency components
Interrupt latency
Sources of interrupt latency
Interrupt handler duration
Interrupt handler implementation
Sources of interrupt handler execution time
Scheduler latency
When is the scheduler run next?
Sources of scheduler latency
Scheduler duration
Sources of scheduler execution time
Other sources of latency
Other sources of latency (2)
Other sources of latency (3)
Issue: priority inversion
Solution: priority inheritance
Issue: interrupt inversion
Benchmarking tools
IMPROVEMENTS IN LINUX 2.6
New preemption options in Linux 2.6
1st option: no forced preemption
2nd option: voluntary kernel preemption
3rd option: preemptible kernel
Other Linux 2.6 improvements
Linux 2.6 improvements - What to remember
LINUX RT-PREEMPT PATCHES
Linux real-time preemption patches
New option: complete real-time preemption
Soft and hard IRQs run in thread context
Priority inheritance support
High-resolution timers
Current issues and limitations
Wrong ideas about real-time preemption
Distributions
Useful reading
DEBUGGING THE REAL-TIME KERNEL
ftrace - kernel function tracer
Using ftrace
Wakeup latency timing option
Latency tracing option - Example
Other tracers
Soft lockup detection
USING THE POSIX REAL-TIME API
Real-time processes
Differences with standard processes
Managing real-time tasks
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Locking pages in RAM
POSIX shared memory (1)
POSIX shared memory (2)
POSIX shared memory (3)
POSIX manual pages
POSIX message queues
Creating and opening a message queue
Posting a message
Receiving a message
POSIX semaphores (1)
POSIX semaphores (2)
POSIX real-time signals (1)
POSIX real-time signals (2)
POSIX clocks and timers
Availabe POSIX clocks (1)
Available POSIX clocks (2)
Time management
Using timers (1)
Using timers (2)
Using high resolution timers
Asynchronous I/O
Compiling instructions
More information on the POSIX interface
Your real-time Linux checklist
LINUX HARD REAL-TIME EXTENSIONS
Linux hard real-time extensions
RTLinux
REAL-TIME IN EMBEDDED LINUX SYSTEMS - RTAI
RTAI project
System architecture
RTAI concepts
RTAI implementation
RTAI usage
RTAI example (1)
RTAI example (2)
Adeos nanokernel
Virtualization
RTAI weaknesses
LINUX HARD REAL-TIME EXTENSIONS - Xenomai
Xenomai project
Xenomai architecture
Most recent kernel versions supported
Kernel versions supported by Xenomai
Xenomai vs. RTAI
COMMERCIAL REAL-TIME DISTRIBUTIONS
Commercial offerings
Montavista
Wind River
TimeSys
BlueCat Linux
Other offerings
Conclusion
Books
References
Related documents
How to help
Thanks
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