This document presents a student project comparing real-time operating systems Linux, Xenomai, and RTAI. It includes an introduction to real-time systems, outlines of Xenomai and RTAI, code snippets showing task creation in Linux and Xenomai, output from running the code in each system, and a conclusion that Xenomai is best for simulating real-time applications due to lower latency than RTAI.

1. ©M. S. Ramaiah University of Applied Sciences
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Faculty of Engineering & Technology
Linux and Xenomai Platform
Sree Nikhilendra Prasad DJ
FT 2014 Batch, Reg. No.: 14ETCS037010
M. Tech. in Real Time Embedded Systems
Module Leader: Ms. Jishmi J. Choondal and Mr. Deepak V.
Module Name: Real Time Operating Systems and System
Programming
Module Code : CSN502

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Faculty of Engineering & Technology
Marking
Head Maximum Score
Technical Content 5
Grasp and Explanation 5
Quality of Slides and
Delivery
5
Q & A 5
Total 20

3. ©M. S. Ramaiah University of Applied Sciences
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Faculty of Engineering & Technology
Presentation Outline
• Introduction
• Xenomai
• RTAI
• Linux Code Snippet
• Linux Output
• Xenomai Code Snippet
• Xenomai Output
• Conclusion
• References

4. ©M. S. Ramaiah University of Applied Sciences
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Faculty of Engineering & Technology
Introduction
• A real time system is the one in which the
correctness of the computation is depended upon
the logical but also upon the span of the
computation carried out.
• A system can be said to be deterministic if the
computation are logically correct and produced on
time without the any interrupts.

5. ©M. S. Ramaiah University of Applied Sciences
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Faculty of Engineering & Technology
Xenomai
• In xenomai, the module will use the standard way
of loading modules in Linux kernel as its entry
point.
• Xenomai consists of the several abstract layers in
which it introduce an enormous flexibility.

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Faculty of Engineering & Technology
RTAI
• RTAI attempts to cut the response times even
further.
• Incoming interrupts that are not registered with
the RTAI are forwarded to the ADEOS and allowing
its nano-kernel to do usual work.

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Faculty of Engineering & Technology
Linux Code Snippet
//function
for(p=1;p<=k;p++)
{
if(x[p]==1)
{ for(m=l;m<tid;m++)
printf("moving upwards %dn",m);
}
else
{ for(m=l;m>tid;m--)
printf("moving downwards %dn",m);
}
}
//Thread Creation
for(j=1;j<=k;j++)
{
printf("ndoor ceasesn");
rc = pthread_create(&threads, NULL, printfloor, (void *)o[j]);
pthread_join(threads,NULL);
}

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Faculty of Engineering & Technology
Linux Output

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Faculty of Engineering & Technology
Xenomai Code snippet
//Task creation and start
for(p=1;p<=n;p++)
{
printf("door ceasesn");
if(x[p]==1)
{
rt_task_spawn(&task_desc2,"MyTaskname2",TASK_STKSZ,TASK_PRIO,TASK_MODE,&
task_body2,NULL);
}
if(x[p]==2)
{
rt_task_spawn(&task_desc,"MyTaskname",TASK_STKSZ,TASK_PRIO,TASK_MODE,&ta
sk_body,NULL);
}
}

10. ©M. S. Ramaiah University of Applied Sciences
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Faculty of Engineering & Technology
Xenomai Output

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Faculty of Engineering & Technology
Conclusion
• Xenomai is best suitable platform to simulate the
real-time application than the RTAI in Linux
operating system.
• RTAI introduces the latency which leads to wrong
computation of the real-time system output.

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Faculty of Engineering & Technology
References
• Jae Hwan Koh and Byoung Wook Choi. (2013)
Real-time Performance of Real-time Mechanisms
for RTAI and Xenomai in Various Running
Conditions, Internationall Journal of Control and
Automation, Vol. 6, No. 1.
• Markus Franke. (2007) A Quantitative Comparison
of Real-time Linux Solutions, Department of
Computer Science, Chemnitz University of
Technology.