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Questions tagged [real-time]

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1answer
17 views

Rate Monotonic maximum execution time

There are several periodic tasks (Period, Execution time), e.g.: A = (20, 9) B = (12, 4) C = (4, X) What methods/tests can be used for finding the maximum execution time X for which the task ...
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4 views

When does a task inherit the priority ceiling in Multiprocessor PCP

In detail: does a task inherit the priority ceiling, only when it is executing the critical section or already when it is selected to run the critical section next (after being blocked for example). I ...
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0answers
38 views

Agreeing on a Time in a Trustless Network

Imagine a chord-like network $N$. each machine $m \in N$ is directly connected to $N_m \subset N$. Without relying on official timeservers, I want all machines to synchronize to some time with ...
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0answers
28 views

Avoiding collisions in space and time

Say I have an image, represented as a 2D array of pixel values. Also, say I have a set of points on that image where each has a current (x, y) position and a Destination (x, y) associated with it. I ...
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24 views

What type of process schedulers are typically used in EKG machines?

I'm researching real-time schedulers for class, and I was trying to think of interesting examples of machines that use real-time schedulers. I thought EKGs would be a good example, so I've been trying ...
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47 views

EDF vs Rate Monotonic

I have to task a set of periodic tasks. Why for EDF is suficient that the utilization factor is <= 1 in order to produce a feasible scheduling, and instead for Rate Monotonic an utilization factor ...
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1answer
33 views

EDF vs Rate Monotonic context changes

I'm studying real time scheduling algorithms. In particular EDF and Rate monotonic. I have an intuition that using EDF we have less context changes than using Rate Monotonic. But i dont know how to ...
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13 views

Real time scheduling activation time

I'm studying the real time scheduling of periodic tasks and some algorithms as EDF,Rate Monotonic and Deadline monotonic. In the all the examples i found,if we have tasks $\tau _{1},...,\tau _{n}$, i ...
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87 views

Deadline Monotonic vs EDF

The deadline monotonic algorithm is used then the deadline is < of the period of the task. In this case, it's also possible to use EDF , or we can use EDF only for periodic tasks for which the ...
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61 views

Utilization Factor, periodic tasks and schedulability

We have 2 periodic tasks that start at the same moment in a monocore processor. Why can happen that, even if the utilization factor is <= 1, the 2 periodic tasks are not schedulable ? For example, ...
3
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1answer
34 views

timed automata - advance only in certain states

I am currently looking into timed automata for a project. I am thinking about a timed automaton where a clock only advances when the automaton is in a certain state. However, my little knowledge in ...
0
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1answer
268 views

Determine deadline for periodic task that enter ready queue in RTOS

I am currently trying to optimise the scheduler of FreeRTOS and in general Real-Time Operating Systems as a Project. In FreeRTOS, and I suspect other RTOS as well, we don't specify the deadline for ...
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3answers
107 views

What does it mean that HDLs “explicitly include the notion of time”?

I got onto the topic of HDLs (Hardware Description Languages) from a comment elsewhere on this site. The Wikipedia article states, rather tantalizingly: One important difference between most ...
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2answers
96 views

How to prove that a system is real-time?

I'm writing a paper on the system I designed which upon receiving an event, performs a number of calculations and publishes the result to several subscribers. I can calculate the amount of time it ...
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0answers
54 views

Neural networks fed with training data on demand?

What I want to achieve is to build a neural network with Keras which will have to stabilize a quadcopter I've built. The network would have three inputs: pitch, roll, yaw, acceleration x, accel y and ...
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0answers
209 views

why p1 misses it first deadline? Rate monotonic scheduling

I understand that rate monotonic scheduling assigns a priority to a process based on the periodicity of the tasks it generates and the process with the shortest inter-task period has the highest ...
0
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1answer
40 views

Are there any efficient algorithems to find packets similarities in a list?

I would like to make a program which finds similar packets (there might be more then one class of similarity) in packet list (which is updated all the time). Are there any efficient algorithems to ...
1
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2answers
603 views

Real time application with DFA or NFA application

Can anyone here give an example of DFA or NFA real time application? And, can I know what are complexity and decidability problems in real time application? Does every real time application have ...
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3answers
962 views

What is 'real time' in a Computer Vision context?

Suppose you have a program which works on a stream of images. It gets an image, makes edits and stores the image. What is the maximum latency with which one can still speak of a "real time application"...
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1answer
96 views

Rate Monotonic First Fit vs. Rate Monotonic Next Fit vs. Proportionate Fair

What would an example of a set of tasks be, where RMFF, RMNF and P-Fair all result in a different number of processors required?
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0answers
317 views

Problems of cyclic executive approach for scheduling of real time systems

I have a doubt on the cyclic executive approach for scheduling on real time systems. From Alan Burns's book Real-time Systems and Programming Languages. This final property represents one of the ...
5
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1answer
308 views

Priority inversion in Hoare and Mesa monitors

I understand the difference between Hoare and Mesa monitors. However I don't understand why priority inversion (when a lower priority process gets done before a higher priority process) is possible in ...
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0answers
150 views

Optimality of EDF

For Earliest Deadline First, I have read that if utilization is less or equal to 1, the task set is schedulable under EDF. But does this criteria expresses the optimality for EDF? If not, how can we ...
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1answer
67 views

Probabilistic Analysis in real time network : Error in data and feedback channel. Two users communication

I'm studying probabilistic analysis in real time network. We have learned how many attempts in average are required to transmit a packet when there is no error on the feedback channel. With no error ...
2
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1answer
2k views

A real-world example for a kind of real-time applications

I submitted a paper regarding hard real-time systems to an engineering journal. But the referees generally agreed my task model is too limited. My task model is a frame-based real-time application ...
5
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1answer
540 views

Can multiple tasks in an RTOS share one stack to save memory?

Many small embedded systems have a limited amount of RAM, 10k or less. I know you can run an RTOS on such systems, however, a realistic number of tasks in such a system is very low, mainly because ...
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3answers
1k views

What guarantees do “soft” real-time operating systems actually provide

I think I know what a "hard" real-time operating system is. It is an operating system with a scheduler that provides a contract with the application programmer. An application provides a deadline ...
5
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1answer
294 views

Realtime hardware/software versus PC software/hardware, how are these distinct and alike?

This question stems from a few answers and comments on a question I posted in signal processing found here. I guess I am a little confused. Are there any concrete differences between realtime ...