Feature/smp granular locks v4 #1154

sudeep-mohanty · 2024-10-09T13:20:58Z

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

Closes Granular Lock for SMP #905

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 · 2024-10-09T13:23:42Z

@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 · 2024-10-09T16:55:58Z

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 · 2024-10-14T22:28:24Z

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

sudeep-mohanty · 2024-10-15T08:26:38Z

@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.

ActoryOu · 2024-10-31T05:02:09Z

Hi @sudeep-mohanty,
Could you help check CI failing?

sudeep-mohanty · 2024-10-31T09:27:52Z

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.

sudeep-mohanty · 2024-11-01T10:57:39Z

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

sonarqubecloud · 2024-11-04T15:38:43Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
6.3% Duplication on New Code

See analysis details on SonarCloud

timers.c

chinglee-iot

Early feedback for this PR.

Some NIT can be improved separately

Review the SMP comment and use the following terms when granular lock feature has different implementation
- SMP with granular lock
- SMP without granular lock

For example,

#ifndef portRELEASE_TASK_LOCK
    #if ( ( portUSING_GRANULAR_LOCKS == 1 ) || ( configNUMBER_OF_CORES == 1 ) )
        #define portRELEASE_TASK_LOCK( xCoreID )
    #else
        #error portRELEASE_TASK_LOCK is required in SMP without granular lock feature
    #endif
#endif /* portRELEASE_TASK_LOCK */

egLOCK/UNLOCK and egENTER/EXIT_CRITICAL macros are used. I am favor of not using abbreviation "eg" here. We can consider to use full name. For example, using the following macros or other macros with full name.

#define event_groupLOCK
#define event_groupUNLOCK
#define event_groupENTER_CRITICAL
#define event_groupEXIT_CRITICAL

I will continue to review the following files and update my review suggestion again.

queue.c
stream_buffer.c
tasks.c

event_groups.c

include/FreeRTOS.h

include/task.h

timers.c

chinglee-iot

Update review suggestion for the following files

queue.c
event_groups.c

Overall review suggestions:

portGET/RELEASE_SPINLOCK should be implemented with thread-safety.
Consider to add coreID as parameter for the following port macros for performance consideration.
- portENTER_CRITICAL_DATA_GROUP
- portEXIT_CRITICAL_DATA_GROUP
- portENTER_CRITICAL_DATA_GROUP_FROM_ISR
- portEXIT_CRITICAL_DATA_GROUP_FROM_ISR
The critical nesting count is used among all the data groups, including tasks.c. Can we move the portXXX_DATA_GROUP implementation back to kernel and use portXXX_CRITICAL_NESTING_COUNT in the implementation?

queue.c

chinglee-iot · 2025-01-23T07:53:11Z

event_groups.c

+            portDISABLE_INTERRUPTS();
+
+            /* Keep holding xTaskSpinlock to prevent tasks on other cores from accessing
+             * the event group while it is suspended. */
+            portGET_SPINLOCK( portGET_CORE_ID(), &( pxEventBits->xTaskSpinlock ) );
+
+            portENABLE_INTERRUPTS();


portGET_SPINLOCK supposed to be thread safe then we can remove the disable/enable interrupts call here.

chinglee-iot · 2025-01-23T08:10:30Z

queue.c

+        /* Keep holding xTaskSpinlock after unlocking the data group to prevent tasks
+         * on other cores from accessing the queue while it is suspended. */
+        portGET_SPINLOCK( portGET_CORE_ID(), &( pxQueue->xTaskSpinlock ) );
+
+        queueEXIT_CRITICAL( pxQueue );


Can we adapt the following change to acquire task spinlock with interrupt enabled?

Suggested change

/* Keep holding xTaskSpinlock after unlocking the data group to prevent tasks

* on other cores from accessing the queue while it is suspended. */

portGET_SPINLOCK( portGET_CORE_ID(), &( pxQueue->xTaskSpinlock ) );

queueEXIT_CRITICAL( pxQueue );

queueEXIT_CRITICAL( pxQueue );

/* Keep holding xTaskSpinlock after unlocking the data group to prevent tasks

* on other cores from accessing the queue while it is suspended. */

portGET_SPINLOCK( portGET_CORE_ID(), &( pxQueue->xTaskSpinlock ) );

chinglee-iot · 2025-01-23T08:14:03Z

stream_buffer.c

+        vTaskPreemptionDisable( NULL );
+
+        /* Lock the stream buffer data group so that we can suspend the stream buffer atomically */
+        sbENTER_CRITICAL( pxStreamBuffer );


Similar reason like other module. portGET_SPINLOCK should be thread safe, then we can remove enter/exit critical section here.

stream_buffer.c

…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 locking macros such as taskENTER/EXIT_CRITICAL() with queueENTER/EXIT_CRITICAL(). - 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 locking macros such as taskENTER/EXIT_CRITICAL() with egENTER/EXIT_CRITICAL(). - 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 locking macros such as taskENTER/EXIT_CRITICAL() with sbENTER/EXIT_CRITICAL(). - 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 locking macros such as taskENTER/EXIT_CRITICAL() with tmrENTER/EXIT_CRITICAL(). Co-authored-by: Sudeep Mohanty <[email protected]>

Co-authored-by: Sudeep Mohanty <[email protected]>

sonarqubecloud · 2025-01-23T10:05:46Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
7.2% Duplication on New Code

See analysis details on SonarQube Cloud

sudeep-mohanty marked this pull request as draft October 15, 2024 08:25

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 marked this pull request as ready for review October 30, 2024 10:34

sudeep-mohanty requested a review from a team as a code owner October 30, 2024 10:34

sudeep-mohanty force-pushed the feature/smp_granular_locks_v4 branch from 5bf8c33 to 9f8acc7 Compare October 31, 2024 09:25

sudeep-mohanty force-pushed the feature/smp_granular_locks_v4 branch 2 times, most recently from c79962d to f50d476 Compare October 31, 2024 12:43

sudeep-mohanty mentioned this pull request Nov 1, 2024

change(freertos/smp/granular_locks): Updated prvYieldCore() coverage tests FreeRTOS/FreeRTOS#1292

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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

sudeep-mohanty marked this pull request as draft November 15, 2024 14:25

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aohzju mentioned this pull request Dec 15, 2024

[BUG]ulTaskGetRunTimeCount(NULL) returns incorrect result #1202

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sudeep-mohanty marked this pull request as ready for review January 14, 2025 14:21

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Dazza0 and others added 10 commits January 23, 2025 11:05

refactor(freertos/smp): Move critical sections inside xTaskPriorityIn…

6d9eae9

…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]>

feat(freertos/smp): Add Granular Locking V4 proposal documents

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Co-authored-by: Sudeep Mohanty <[email protected]>

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Feature/smp granular locks v4 #1154

Feature/smp granular locks v4 #1154

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Feature/smp granular locks v4 #1154

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sudeep-mohanty commented Oct 9, 2024 • edited Loading

Description

Test Steps

TODO

Checklist:

Related Issue

sudeep-mohanty commented Oct 9, 2024

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sudeep-mohanty commented Oct 31, 2024

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