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@sudeep-mohanty sudeep-mohanty commented Oct 9, 2024

This PR adds support for granular locking to the FreeRTOS kernel.

Description

Granular locking introduces the concept of having localized locks per kernel data group for SMP configuration. This method is an optional replacement of the existing kernel locks and is controlled by a new port layer configuration, viz., portUSING_GRANULAR_LOCKS. More details about the approach can be found here.

Test Steps

The implementation has been tested on Espressif SoC targets, viz., the ESP32 using the ESP-IDF framework.

1. Testing on an esp32 target

  • To test the implementation of the granular locking scheme on esp32, setup the ESP-IDF environment on your local machine. The steps to follow are listed in the Getting Started Guide.
  • Instead of the main ESP-IDF repository, the granular locks implementation resides in this froked repository - https://github.com/sudeep-mohanty/esp-idf.
  • Once you have cloned the forked repository and setup the ESP-IDF environment, change your branch to feat/granular_locks_tests.
  • To run the FreeRTOS unit tests, change the directory to components/freertos/test_apps/freertos where all the test cases are located.
  • Performance tests are located in the performance subfolder at the same location.
  • Setup the target device with the command idf.py seet-target esp32.
  • Select the Amazon FreeRTOS SMP kernel using the menuconfig options. To do this you must enter the command -idf.py menuconfig -> Component config -> FreeRTOS -> Kernel -> Run the Amazon SMP FreeRTOS kernel instead (FEATURE UNDER DEVELOPMENT). Save the configuration and exit the menuconfig.
  • Now, build and flash the unit test application with the command idf.py build flash monitor.
  • Once the app is up, you can enter the number of the test case and run the unity test case.

TODO

  • Test setup for other targets (Raspberry Pi Pico)
  • Generic target tests to be uploaded to the FreeRTOS repository.

Checklist:

  • I have tested my changes. No regression in existing tests.
  • I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

@sudeep-mohanty
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@chinglee-iot @aggarg This PR introduces the granular locks changes to the FreeRTOS kernel. Please have a look and we could have discussions/changes in this PR context. Thank you.

cc: @ESP-Marius @Dazza0

@rawalexe
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rawalexe commented Oct 9, 2024

Thank you for your contribution, I'll forward this request to the team. There are few error in the PR can you please try fixing them

@rawalexe
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Hello @sudeep-mohanty, I am just following up if you had time to fix the build issues

@sudeep-mohanty sudeep-mohanty marked this pull request as draft October 15, 2024 08:25
@sudeep-mohanty
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@rawalexe Yes! I shall work on the failures and would also do some refactoring for an easier review process. For now, I've put this PR in draft.

@sudeep-mohanty sudeep-mohanty force-pushed the feature/smp_granular_locks_v4 branch 9 times, most recently from 0159a4a to 5bf8c33 Compare October 30, 2024 10:26
@sudeep-mohanty sudeep-mohanty marked this pull request as ready for review October 30, 2024 10:34
@sudeep-mohanty sudeep-mohanty requested a review from a team as a code owner October 30, 2024 10:34
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Hi @sudeep-mohanty,
Could you help check CI failing?

@sudeep-mohanty sudeep-mohanty force-pushed the feature/smp_granular_locks_v4 branch from 5bf8c33 to 9f8acc7 Compare October 31, 2024 09:25
@sudeep-mohanty
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Hi @sudeep-mohanty, Could you help check CI failing?

Hi @ActoryOu, I've made some updates which should fix the CI failures however I could not understand why the link-verifier action fails. Seems more like a script failure to me. So this action would still fail. If you have more information on what is causing it, could you let me know and I shall fix it. Thanks.

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sudeep-mohanty commented Nov 1, 2024

Created a PR to fix the CI failure - FreeRTOS/FreeRTOS#1292

@sudeep-mohanty sudeep-mohanty force-pushed the feature/smp_granular_locks_v4 branch 4 times, most recently from 70eb466 to edc1c98 Compare November 4, 2024 15:38
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sonarqubecloud bot commented Nov 4, 2024

@sudeep-mohanty sudeep-mohanty marked this pull request as draft November 15, 2024 14:25
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moninom1 pushed a commit to moninom1/FreeRTOS-Kernel that referenced this pull request Sep 30, 2025
Dazza0 and others added 26 commits October 13, 2025 10:34
…herit()

xTaskPriorityInherit() is called inside a critical section from queue.c. This
commit moves the critical section into xTaskPriorityInherit().

Co-authored-by: Sudeep Mohanty <[email protected]>
Changed xPreemptionDisable to be a count rather than a pdTRUE/pdFALSE. This
allows nested calls to vTaskPreemptionEnable(), where a yield only occurs when
xPreemptionDisable is 0.

Co-authored-by: Sudeep Mohanty <[email protected]>
Adds the required checks for granular locking port macros.

Port Config:

- portUSING_GRANULAR_LOCKS to enable granular locks
- portCRITICAL_NESTING_IN_TCB should be disabled

Granular Locking Port Macros:

- Spinlocks
        - portSPINLOCK_TYPE
        - portINIT_SPINLOCK( pxSpinlock )
        - portINIT_SPINLOCK_STATIC
- Locking
        - portGET_SPINLOCK()
        - portRELEASE_SPINLOCK()

Co-authored-by: Sudeep Mohanty <[email protected]>
- Updated prvCheckForRunStateChange() for granular locks
- Updated vTaskSuspendAll() and xTaskResumeAll()
    - Now holds the xTaskSpinlock during kernel suspension
    - Increments/decrements xPreemptionDisable. Only yields when 0, thus allowing
    for nested suspensions across different data groups

Co-authored-by: Sudeep Mohanty <[email protected]>
Updated critical section macros with granular locks.

Some tasks.c API relied on their callers to enter critical sections. This
assumption no longer works under granular locking. Critical sections added to
the following functions:

- `vTaskInternalSetTimeOutState()`
- `xTaskIncrementTick()`
- `vTaskSwitchContext()`
- `xTaskRemoveFromEventList()`
- `vTaskInternalSetTimeOutState()`
- `eTaskConfirmSleepModeStatus()`
- `xTaskPriorityDisinherit()`
- `pvTaskIncrementMutexHeldCount()`

Added missing suspensions to the following functions:

- `vTaskPlaceOnEventList()`
- `vTaskPlaceOnUnorderedEventList()`
- `vTaskPlaceOnEventListRestricted()`

Fixed the locking in vTaskSwitchContext()

vTaskSwitchContext() must aquire both kernel locks, viz., task lock and
ISR lock. This is because, vTaskSwitchContext() can be called from
either task context or ISR context. Also, vTaskSwitchContext() must not
alter the interrupt state prematurely.

Co-authored-by: Sudeep Mohanty <[email protected]>
Updated queue.c to use granular locking

- Added xTaskSpinlock and xISRSpinlock
- Replaced  critical section macros with data group critical section macros
such as taskENTER/EXIT_CRITICAL/_FROM_ISR() with queueENTER/EXIT_CRITICAL_FROM_ISR().
- Added vQueueEnterCritical/FromISR() and vQueueExitCritical/FromISR()
  which map to the data group critical section macros.
- Added prvLockQueueForTasks() and prvUnlockQueueForTasks() as the granular locking equivalents
to prvLockQueue() and prvUnlockQueue() respectively

Co-authored-by: Sudeep Mohanty <[email protected]>
Updated event_groups.c to use granular locking

- Added xTaskSpinlock and xISRSpinlock
- Replaced critical section macros with data group critical section macros
such as taskENTER/EXIT_CRITICAL/_FROM_ISR() with event_groupsENTER/EXIT_CRITICAL/_FROM_ISR().
- Added vEventGroupsEnterCritical/FromISR() and
  vEventGroupsExitCriti/FromISR() functions that map to the data group
critical section macros.
- Added prvLockEventGroupForTasks() and prvUnlockEventGroupForTasks() to suspend the event
group when executing non-deterministic code.
- xEventGroupSetBits() and vEventGroupDelete() accesses the kernel data group
directly. Thus, added vTaskSuspendAll()/xTaskResumeAll() to these fucntions.

Co-authored-by: Sudeep Mohanty <[email protected]>
Updated stream_buffer.c to use granular locking

- Added xTaskSpinlock and xISRSpinlock
- Replaced critical section macros with data group critical section macros
such as taskENTER/EXIT_CRITICAL/_FROM_ISR() with sbENTER/EXIT_CRITICAL_FROM_ISR().
- Added vStreambuffersEnterCritical/FromISR() and
  vStreambuffersExitCritical/FromISR() to map to the data group critical
section macros.
- Added prvLockStreamBufferForTasks() and prvUnlockStreamBufferForTasks() to suspend the stream
buffer when executing non-deterministic code.

Co-authored-by: Sudeep Mohanty <[email protected]>
Updated timers.c to use granular locking

- Added xTaskSpinlock and xISRSpinlock
- Replaced critical section macros with data group critical section macros
such as taskENTER/EXIT_CRITICAL() with tmrENTER/EXIT_CRITICAL().
- Added vTimerEnterCritical() and vTimerExitCritical() to map to the
  data group critical section macros.

Co-authored-by: Sudeep Mohanty <[email protected]>
This commit removes the need for suspending the scheduler when calling
some event_groups.c APIs as the non-deterministic operations are
happening with the event group being locked and the preemption being
disabled from the current task.
@sudeep-mohanty sudeep-mohanty force-pushed the feature/smp_granular_locks_v4 branch from b20d191 to 1b91c54 Compare October 13, 2025 08:34
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Granular Lock for SMP

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