What is a mutex FreeRTOS?
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What is a mutex FreeRTOS?
A mutex (short for MUTual EXclusion) is a flag or lock used to allow only one thread to access a section of code at a time. It blocks (or locks out) all other threads from accessing the code or resource.
What is deadlock in FreeRTOS?
Deadlock is a phenomenon when two tasks are in a blocked state waiting for the resources held by one and another simultaneously.
Does FreeRTOS have threads?
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How does mutex prevent priority inversion?
Whenever a task locks a mutex, its priority is automatically raised to the ceiling priority for that mutex. In other words, when any task locks a mutex, its priority is raised to the level, or above that, of all tasks that may want to lock the mutex.
What is starvation in FreeRTOS?
If you design your application so that a task will starve then it will starve. If you design priority inversion into you app then this will happen also. FreeRTOS will do what you ask it to do and (hopefully) behave in a deterministic way when doing so. It does not change your design.
How can we avoid deadlock in RTOS?
Deadlock can be prevented by eliminating any of the four necessary conditions, which are mutual exclusion, hold and wait, no preemption, and circular wait. Mutual exclusion, hold and wait and no preemption cannot be violated practically. Circular wait can be feasibly eliminated by assigning a priority to each resource.
What is a message queue in RTOS?
Message queues are kernel objects used to pass content to a task. Messages are typically void pointers to a storage area containing the actual message. However, the pointer can point to anything, even a function for the receiving task to execute. The meaning of the message is thus application-dependent.
How do I fix priority inversion?
One way to solve priority inversion is to use the priority ceiling protocol , which gives each shared resource a predefined priority ceiling. When a task acquires a shared resource, the task is hoisted (has its priority temporarily raised) to the priority ceiling of that resource.
What are the types of priorities in RTOS?
The decision of what task to execute is known as task scheduling and most RTOS use fixed-priority scheduling (FPS), where the developers assign each task a static priority level to indicate their relative urgency.
What is task starvation?
Starvation is usually caused by an overly simplistic scheduling algorithm. For example, if a (poorly designed) multi-tasking system always switches between the first two tasks while a third never gets to run, then the third task is being starved of CPU time.
