Linux Task

Spawn task function as separate Linux thread

expand all in page

Add-On Required: This feature requires the Embedded Coder Support Package for ARM Cortex-A Processors add-on.

  • Linux Task block

Libraries:
Embedded Coder Support Package for ARM Cortex-A Processors

Description

Use this block to create a task function that spawns as a separate Linux® thread. The task function runs the code of the downstream Function-Call Subsystem block.

Examples

Creating Linux Task Threads

Creating Linux Task Threads

Create Linux® task threads using the Linux Task block of Embedded Coder® Support Package for ARM® Cortex®-A Processors.

Ports

Output

expand all

A function-call control signal that triggers a Function-Call Subsystem block.

Parameters

expand all

To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Specify a name for this task. You can enter at most 32 characters consisting of letters, numbers, or a combination of letters and numbers.

Programmatic Use

Block Parameter: taskName

Select the scheduling policy that applies to this thread. You can choose from these options:

  • SCHED_FIFO — This option enables a first-in, first-out (FIFO) scheduling algorithm that executes real-time processes without time slicing. With FIFO scheduling, a higher-priority process preempts a lower-priority process. The lower-priority process remains at the top of the list for its priority and resumes execution when the scheduler blocks all higher-priority processes.

    For example, in the FIFO scheduling image, task2 preempts task1, and task3 preempts task2. When task3 completes, task2 resumes. When task2 completes, task1 resumes.

    The Linux Task block uses FIFO scheduling.

    SCHED_FIFO displays the Thread priority parameter on which you can set to a value from 1 to 99.

  • SCHED_OTHER — This option enables the default Linux time-sharing scheduling algorithm. You can use this scheduling for all processes except those requiring special static priority real-time mechanisms. With this algorithm, the scheduler chooses processes based on their dynamic priority within the static priority 0 list. Each time the process is ready to run and the scheduler denies it, the operating system increases the dynamic priority of that process. Such prioritization helps the scheduler serve the SCHED_OTHER processes.

    Selecting SCHED_OTHER hides the Thread priority parameter and sets the thread priority to 0.

Programmatic Use

Block Parameter: taskPolicy

Specify the priority of the Linux thread. A value of 1 indicates a low priority, and a value of 99 indicates a high priority. Higher-priority tasks can preempt lower-priority tasks.

To enable this parameter, set Thread scheduling policy to SCHED_FIFO.

To enable this parameter, set Thread scheduling policy to SCHED_FIFO.

Programmatic Use

Block Parameter: taskPriority

Version History

Introduced in R2014a

See Also

|