kopia lustrzana https://github.com/espressif/esp-idf
docs: link to FreeRTOS APIs from SMP changes documentation
Ivan Grokhotkov
rodzic
66fe94f816
commit
6f90393f22
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@ -20,8 +20,8 @@ found via http://www.freertos.org/a00106.html
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port of FreeRTOS v8.2.0, a number of FreeRTOS v9.0.0 features have been backported
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to ESP-IDF.
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:ref:`tasks-and-task-creation`: Use ``xTaskCreatePinnedToCore()`` or
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``xTaskCreateStaticPinnedToCore()`` to create tasks in ESP-IDF FreeRTOS. The
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:ref:`tasks-and-task-creation`: Use :cpp:func:`xTaskCreatePinnedToCore` or
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:cpp:func:`xTaskCreateStaticPinnedToCore` to create tasks in ESP-IDF FreeRTOS. The
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last parameter of the two functions is ``xCoreID``. This parameter specifies
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which core the task is pinned to. Acceptable values are ``0`` for **PRO_CPU**,
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``1`` for **APP_CPU**, or ``tskNO_AFFINITY`` which allows the task to run on
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@ -34,13 +34,13 @@ enter a blocked state, or are distributed across a wider range of priorities.
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:ref:`scheduler-suspension`: Suspending the scheduler in ESP-IDF FreeRTOS will only
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affect the scheduler on the the calling core. In other words, calling
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``vTaskSuspendAll()`` on **PRO_CPU** will not prevent **APP_CPU** from scheduling, and
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:cpp:func:`vTaskSuspendAll` on **PRO_CPU** will not prevent **APP_CPU** from scheduling, and
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vice versa. Use critical sections or semaphores instead for simultaneous
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access protection.
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:ref:`tick-interrupt-synchronicity`: Tick interrupts of **PRO_CPU** and **APP_CPU**
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are not synchronized. Do not expect to use ``vTaskDelay`` or
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``vTaskDelayUntil`` as an accurate method of synchronizing task execution
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are not synchronized. Do not expect to use :cpp:func:`vTaskDelay` or
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:cpp:func:`vTaskDelayUntil` as an accurate method of synchronizing task execution
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between the two cores. Use a counting semaphore instead as their context
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switches are not tied to tick interrupts due to preemption.
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@ -51,15 +51,15 @@ unaffected. If the other core attemps to take same mutex, it will spin until
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the calling core has released the mutex by exiting the critical section.
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:ref:`floating-points`: The ESP32 supports hardware acceleration of single
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precision floating point arithmetic (`float`). However the use of hardware
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precision floating point arithmetic (``float``). However the use of hardware
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acceleration leads to some behavioral restrictions in ESP-IDF FreeRTOS.
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Therefore, tasks that utilize `float` will automatically be pinned to a core if
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not done so already. Furthermore, `float` cannot be used in interrupt service
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Therefore, tasks that utilize ``float`` will automatically be pinned to a core if
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not done so already. Furthermore, ``float`` cannot be used in interrupt service
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routines.
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:ref:`task-deletion`: Task deletion behavior has been backported from FreeRTOS
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v9.0.0 and modified to be SMP compatible. Task memory will be freed immediately
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when `vTaskDelete()` is called to delete a task that is not currently running
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when :cpp:func:`vTaskDelete` is called to delete a task that is not currently running
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and not pinned to the other core. Otherwise, freeing of task memory will still
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be delegated to the Idle Task.
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@ -67,7 +67,7 @@ be delegated to the Idle Task.
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Storage Pointers (TLSP) feature. However the extra feature of Deletion Callbacks has been
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added. Deletion callbacks are called automatically during task deletion and are
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used to free memory pointed to by TLSP. Call
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``vTaskSetThreadLocalStoragePointerAndDelCallback()`` to set TLSP and Deletion
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:cpp:func:`vTaskSetThreadLocalStoragePointerAndDelCallback()` to set TLSP and Deletion
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Callbacks.
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:ref:`FreeRTOS Hooks<hooks_api_reference>`: Vanilla FreeRTOS Hooks were not designed for SMP.
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@ -94,34 +94,34 @@ This feature has been backported from FreeRTOS v9.0.0 to ESP-IDF. The
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in order for static allocation functions to be available. Once enabled, the
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following functions can be called...
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- ``xTaskCreateStatic()`` See :ref:`backporting-notes` below
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- ``xQueueCreateStatic()``
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- ``xSemaphoreCreateBinaryStatic()``
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- ``xSemaphoreCreateCountingStatic()``
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- ``xSemaphoreCreateMutexStatic()``
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- ``xSemaphoreCreateRecursiveMutexStatic()``
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- ``xTimerCreateStatic()`` See :ref:`backporting-notes` below
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- ``xEventGroupCreateStatic()``
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- :cpp:func:`xTaskCreateStatic` (see :ref:`backporting-notes` below)
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- :c:macro:`xQueueCreateStatic`
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- :c:macro:`xSemaphoreCreateBinaryStatic`
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- :c:macro:`xSemaphoreCreateCountingStatic`
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- :c:macro:`xSemaphoreCreateMutexStatic`
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- :c:macro:`xSemaphoreCreateRecursiveMutexStatic`
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- :cpp:func:`xTimerCreateStatic` (see :ref:`backporting-notes` below)
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- :cpp:func:`xEventGroupCreateStatic`
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Other Features
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^^^^^^^^^^^^^^
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- ``vTaskSetThreadLocalStoragePointer()`` See :ref:`backporting-notes` below
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- ``pvTaskGetThreadLocalStoragePointer()`` See :ref:`backporting-notes` below
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- ``vTimerSetTimerID()``
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- ``xTimerGetPeriod()``
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- ``xTimerGetExpiryTime()``
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- ``pcQueueGetName()``
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- ``uxSemaphoreGetCount()``
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- :cpp:func:`vTaskSetThreadLocalStoragePointer` (see :ref:`backporting-notes` below)
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- :cpp:func:`pvTaskGetThreadLocalStoragePointer` (see :ref:`backporting-notes` below)
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- :cpp:func:`vTimerSetTimerID`
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- :cpp:func:`xTimerGetPeriod`
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- :cpp:func:`xTimerGetExpiryTime`
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- :cpp:func:`pcQueueGetName`
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- :c:macro:`uxSemaphoreGetCount`
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.. _backporting-notes:
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Backporting Notes
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^^^^^^^^^^^^^^^^^
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**1)** ``xTaskCreateStatic`` has been made SMP compatible in a similar
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fashion to ``xTaskCreate`` (see :ref:`tasks-and-task-creation`). Therefore
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``xTaskCreateStaticPinnedToCore()`` can also be called.
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**1)** :cpp:func:`xTaskCreateStatic` has been made SMP compatible in a similar
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fashion to :cpp:func:`xTaskCreate` (see :ref:`tasks-and-task-creation`). Therefore
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:cpp:func:`xTaskCreateStaticPinnedToCore` can also be called.
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**2)** Although vanilla FreeRTOS allows the Timer feature's daemon task to
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be statically allocated, the daemon task is always dynamically allocated in
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@ -130,7 +130,7 @@ defined when using statically allocated timers in ESP-IDF FreeRTOS.
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**3)** The Thread Local Storage Pointer feature has been modified in ESP-IDF
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FreeRTOS to include Deletion Callbacks (see :ref:`deletion-callbacks`). Therefore
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the function ``vTaskSetThreadLocalStoragePointerAndDelCallback()`` can also be
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the function :cpp:func:`vTaskSetThreadLocalStoragePointerAndDelCallback` can also be
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called.
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@ -142,9 +142,9 @@ Tasks and Task Creation
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Tasks in ESP-IDF FreeRTOS are designed to run on a particular core, therefore
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two new task creation functions have been added to ESP-IDF FreeRTOS by
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appending ``PinnedToCore`` to the names of the task creation functions in
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vanilla FreeRTOS. The vanilla FreeRTOS functions of ``xTaskCreate()``
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and ``xTaskCreateStatic()`` have led to the addition of
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``xTaskCreatePinnedToCore()`` and ``xTaskCreateStaticPinnedToCore()`` in
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vanilla FreeRTOS. The vanilla FreeRTOS functions of :cpp:func:`xTaskCreate`
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and :cpp:func:`xTaskCreateStatic` have led to the addition of
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:cpp:func:`xTaskCreatePinnedToCore` and :cpp:func:`xTaskCreateStaticPinnedToCore` in
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ESP-IDF FreeRTOS (see :ref:`backported-features`).
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For more details see :component_file:`freertos/task.c`
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@ -164,9 +164,9 @@ of 1000 bytes. It should be noted that the ``uxStackDepth`` parameter in
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vanilla FreeRTOS specifies a task’s stack depth in terms of the number of
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words, whereas ESP-IDF FreeRTOS specifies the stack depth in terms of bytes.
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Note that the vanilla FreeRTOS functions ``xTaskCreate`` and
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``xTaskCreateStatic`` have been macro defined in ESP-IDF FreeRTOS to call
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``xTaskCreatePinnedToCore()`` and ``xTaskCreateStaticPinnedToCore()``
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Note that the vanilla FreeRTOS functions :cpp:func:`xTaskCreate` and
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:cpp:func:`xTaskCreateStatic` have been defined in ESP-IDF FreeRTOS as inline functions which call
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:cpp:func:`xTaskCreatePinnedToCore` and :cpp:func:`xTaskCreateStaticPinnedToCore`
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respectively with ``tskNO_AFFINITY`` as the ``xCoreID`` value.
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Each Task Control Block (TCB) in ESP-IDF stores the ``xCoreID`` as a member.
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@ -283,18 +283,18 @@ different cores.
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Scheduler Suspension
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^^^^^^^^^^^^^^^^^^^^
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In vanilla FreeRTOS, suspending the scheduler via ``vTaskSuspendAll()`` will
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prevent calls of ``vTaskSwitchContext()`` from context switching until the
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scheduler has been resumed with ``vTaskResumeAll()``. However servicing ISRs
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In vanilla FreeRTOS, suspending the scheduler via :cpp:func:`vTaskSuspendAll` will
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prevent calls of ``vTaskSwitchContext`` from context switching until the
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scheduler has been resumed with :cpp:func:`xTaskResumeAll`. However servicing ISRs
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are still permitted. Therefore any changes in task states as a result from the
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current running task or ISRSs will not be executed until the scheduler is
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resumed. Scheduler suspension in vanilla FreeRTOS is a common protection method
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against simultaneous access of data shared between tasks, whilst still allowing
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ISRs to be serviced.
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In ESP-IDF FreeRTOS, ``vTaskSuspendAll()`` will only prevent calls of
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In ESP-IDF FreeRTOS, :cpp:func:`xTaskResumeAll` will only prevent calls of
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``vTaskSwitchContext()`` from switching contexts on the core that called for the
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suspension. Hence if **PRO_CPU** calls ``vTaskSuspendAll()``, **APP_CPU** will
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suspension. Hence if **PRO_CPU** calls :cpp:func:`vTaskSuspendAll`, **APP_CPU** will
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still be able to switch contexts. If data is shared between tasks that are
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pinned to different cores, scheduler suspension is **NOT** a valid method of
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protection against simultaneous access. Consider using critical sections
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@ -302,7 +302,7 @@ protection against simultaneous access. Consider using critical sections
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protecting shared resources in ESP-IDF FreeRTOS.
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In general, it's better to use other RTOS primitives like mutex semaphores to protect
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against data shared between tasks, rather than ``vTaskSuspendAll()``.
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against data shared between tasks, rather than :cpp:func:`vTaskSuspendAll`.
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.. _tick-interrupt-synchronicity:
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@ -316,8 +316,8 @@ each core being independent, and the tick interrupts to each core being
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unsynchronized.
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In vanilla FreeRTOS the tick interrupt triggers a call to
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``xTaskIncrementTick()`` which is responsible for incrementing the tick
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counter, checking if tasks which have called ``vTaskDelay()`` have fulfilled
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:cpp:func:`xTaskIncrementTick` which is responsible for incrementing the tick
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counter, checking if tasks which have called :cpp:func:`vTaskDelay` have fulfilled
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their delay period, and moving those tasks from the Delayed Task List to the
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Ready Task List. The tick interrupt will then call the scheduler if a context
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switch is necessary.
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@ -372,11 +372,11 @@ The ESP-IDF FreeRTOS critical section functions have been modified as follows…
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- ``taskENTER_CRITICAL(mux)``, ``taskENTER_CRITICAL_ISR(mux)``,
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``portENTER_CRITICAL(mux)``, ``portENTER_CRITICAL_ISR(mux)`` are all macro
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defined to call ``vTaskEnterCritical()``
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defined to call :cpp:func:`vTaskEnterCritical`
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- ``taskEXIT_CRITICAL(mux)``, ``taskEXIT_CRITICAL_ISR(mux)``,
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``portEXIT_CRITICAL(mux)``, ``portEXIT_CRITICAL_ISR(mux)`` are all macro
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defined to call ``vTaskExitCritical()``
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defined to call :cpp:func:`vTaskExitCritical`
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For more details see :component_file:`freertos/include/freertos/portmacro.h`
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and :component_file:`freertos/task.c`
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@ -394,23 +394,23 @@ Floating Point Aritmetic
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------------------------
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The ESP32 supports hardware acceleration of single precision floating point
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arithmetic (`float`) via Floating Point Units (FPU, also known as coprocessors)
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arithmetic (``float``) via Floating Point Units (FPU, also known as coprocessors)
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attached to each core. The use of the FPUs imposes some behavioral restrictions
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on ESP-IDF FreeRTOS.
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ESP-IDF FreeRTOS implements Lazy Context Switching for FPUs. In other words,
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the state of a core's FPU registers are not immediately saved when a context
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switch occurs. Therefore, tasks that utilize `float` must be pinned to a
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switch occurs. Therefore, tasks that utilize ``float`` must be pinned to a
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particular core upon creation. If not, ESP-IDF FreeRTOS will automatically pin
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the task in question to whichever core the task was running on upon the task's
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first use of `float`. Likewise due to Lazy Context Switching, interrupt service
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routines must also not use `float`.
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first use of ``float``. Likewise due to Lazy Context Switching, interrupt service
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routines must also not use ``float``.
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ESP32 does not support hardware acceleration for double precision floating point
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arithmetic (`double`). Instead `double` is implemented via software hence the
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behavioral restrictions with regards to `float` do not apply to `double`. Note
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that due to the lack of hardware acceleration, `double` operations may consume
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significantly larger amount of CPU time in comparison to `float`.
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arithmetic (``double``). Instead ``double`` is implemented via software hence the
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behavioral restrictions with regards to ``float`` do not apply to ``double``. Note
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that due to the lack of hardware acceleration, ``double`` operations may consume
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significantly larger amount of CPU time in comparison to ``float``.
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.. _task-deletion:
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@ -420,12 +420,12 @@ Task Deletion
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FreeRTOS task deletion prior to v9.0.0 delegated the freeing of task memory
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entirely to the Idle Task. Currently, the freeing of task memory will occur
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immediately (within `vTaskDelete()`) if the task being deleted is not currently
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immediately (within :cpp:func:`vTaskDelete`) if the task being deleted is not currently
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running or is not pinned to the other core (with respect to the core
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`vTaskDelete()` is called on). TLSP deletion callbacks will also run immediately
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:cpp:func:`vTaskDelete` is called on). TLSP deletion callbacks will also run immediately
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if the same conditions are met.
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However, calling `vTaskDelete()` to delete a task that is either currently
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However, calling :cpp:func:`vTaskDelete` to delete a task that is either currently
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running or pinned to the other core will still result in the freeing of memory
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being delegated to the Idle Task.
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@ -456,8 +456,8 @@ is the index number of the associated TLSP, and the second parameter is the
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TLSP itself.
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Deletion callbacks are set alongside TLSP by calling
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``vTaskSetThreadLocalStoragePointerAndDelCallback()``. Calling the vanilla
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FreeRTOS function ``vTaskSetThreadLocalStoragePointer()`` will simply set the
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:cpp:func:`vTaskSetThreadLocalStoragePointerAndDelCallback`. Calling the vanilla
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FreeRTOS function :cpp:func:`vTaskSetThreadLocalStoragePointer` will simply set the
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TLSP's associated Deletion Callback to `NULL` meaning that no callback will be
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called for that TLSP during task deletion. If a deletion callback is `NULL`,
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users should manually free the memory pointed to by the associated TLSP before
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@ -466,7 +466,7 @@ task deletion in order to avoid memory leak.
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:ref:`CONFIG_FREERTOS_THREAD_LOCAL_STORAGE_POINTERS` in menuconfig can be used
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to configure the number TLSP and Deletion Callbacks a TCB will have.
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For more details see :component_file:`freertos/include/freertos/task.h`
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For more details see :doc:`FreeRTOS API reference<../api-reference/system/freertos>`.
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.. _esp-idf-freertos-configuration:
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@ -491,9 +491,9 @@ number of Thread Local Storage Pointers each task will have in ESP-IDF
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FreeRTOS.
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:ref:`CONFIG_SUPPORT_STATIC_ALLOCATION` will enable the backported
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functionality of ``xTaskCreateStaticPinnedToCore()`` in ESP-IDF FreeRTOS
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functionality of :cpp:func:`xTaskCreateStaticPinnedToCore` in ESP-IDF FreeRTOS
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:ref:`CONFIG_FREERTOS_ASSERT_ON_UNTESTED_FUNCTION` will trigger a halt in
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particular functions in ESP-IDF FreeRTOS which have not been fully tested
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in an SMP context.
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