alex/esp-idf
1
0
Fork 0
mirror of https://github.com/espressif/esp-idf.git synced 2025-10-27 20:04:21 +00:00
Code Issues Packages Projects Releases Wiki Activity

Merge branch 'bugfix/freertos_round_robin_scheduling_retain_skip_v4.3' into 'release/v4.3'

Browse Source 
freertos: Implement best effort round robin scheduling (v4.3)

See merge request espressif/esp-idf!16542
This commit is contained in:
Zim Kalinowski
2021-12-31 02:58:53 +00:00
parent 04d2887493 e9cbf56d36
commit aef7850157
6 changed files with 346 additions and 208 deletions
Download Patch File Download Diff File Expand all files Collapse all files

231
components/freertos/tasks.c
View File

@@ -131,22 +131,10 @@ configIDLE_TASK_NAME in FreeRTOSConfig.h. */
/*-----------------------------------------------------------*/
#define taskSELECT_HIGHEST_PRIORITY_TASK() \
{ \
UBaseType_t uxTopPriority = uxTopReadyPriority; \
\
/* Find the highest priority queue that contains ready tasks. */ \
while( listLIST_IS_EMPTY( &( pxReadyTasksLists[ uxTopPriority ] ) ) ) \
{ \
configASSERT( uxTopPriority ); \
--uxTopPriority; \
} \
\
/* listGET_OWNER_OF_NEXT_ENTRY indexes through the list, so the tasks of \
the same priority get an equal share of the processor time. */ \
listGET_OWNER_OF_NEXT_ENTRY( pxCurrentTCB[xPortGetCoreID()], &( pxReadyTasksLists[ uxTopPriority ] ) ); \
uxTopReadyPriority = uxTopPriority; \
} /* taskSELECT_HIGHEST_PRIORITY_TASK */
/* SMP does not support optimized selection while single-core configuration
can choose whether or not optimized selection is used. Therefore, this SMP
selection function must work for single-core and SMP */
#define taskSELECT_HIGHEST_PRIORITY_TASK() taskSelectHighestPriorityTaskSMP()
/*-----------------------------------------------------------*/
@@ -3245,11 +3233,98 @@ BaseType_t xSwitchRequired = pdFALSE;
#endif /* configUSE_APPLICATION_TASK_TAG */
/*-----------------------------------------------------------*/
#if ( configUSE_PORT_OPTIMISED_TASK_SELECTION == 0 )
static void taskSelectHighestPriorityTaskSMP( void )
{
/* This function is called from a critical section. So some optimizations are made */
BaseType_t uxCurPriority;
BaseType_t xTaskScheduled = pdFALSE;
BaseType_t xNewTopPrioritySet = pdFALSE;
BaseType_t xCoreID = xPortGetCoreID(); /* Optimization: Read once */
/* Search for tasks, starting form the highest ready priority. If nothing is
* found, we eventually default to the IDLE tasks at priority 0 */
for ( uxCurPriority = uxTopReadyPriority; uxCurPriority >= 0 && xTaskScheduled == pdFALSE; uxCurPriority-- )
{
/* Check if current priority has one or more ready tasks. Skip if none */
if( listLIST_IS_EMPTY( &( pxReadyTasksLists[ uxCurPriority ] ) ) )
{
continue;
}
/* Save a copy of highest priority that has a ready state task */
if( xNewTopPrioritySet == pdFALSE )
{
xNewTopPrioritySet = pdTRUE;
uxTopReadyPriority = uxCurPriority;
}
/* We now search this priority's ready task list for a runnable task.
* We always start searching from the head of the list, so we reset
* pxIndex to point to the tail so that we start walking the list from
* the first item */
pxReadyTasksLists[ uxCurPriority ].pxIndex = ( ListItem_t * ) &( pxReadyTasksLists[ uxCurPriority ].xListEnd );
/* Get the first item on the list */
TCB_t * pxTCBCur;
TCB_t * pxTCBFirst;
listGET_OWNER_OF_NEXT_ENTRY( pxTCBCur, &( pxReadyTasksLists[ uxCurPriority ] ) );
pxTCBFirst = pxTCBCur;
do
{
/* Check if the current task is currently being executed. However, if
* it's being executed by the current core, we can still schedule it.
* Todo: Each task can store a xTaskRunState, instead of needing to
* check each core */
UBaseType_t ux;
for( ux = 0; ux < ( UBaseType_t )portNUM_PROCESSORS; ux++ )
{
if ( ux == xCoreID )
{
continue;
}
else if ( pxCurrentTCB[ux] == pxTCBCur )
{
/* Current task is already being executed. Get the next task */
goto get_next_task;
}
}
/* Check if the current task has a compatible affinity */
if ( ( pxTCBCur->xCoreID != xCoreID ) && ( pxTCBCur->xCoreID != tskNO_AFFINITY ) )
{
goto get_next_task;
}
/* The current task is runnable. Schedule it */
pxCurrentTCB[ xCoreID ] = pxTCBCur;
xTaskScheduled = pdTRUE;
/* Move the current tasks list item to the back of the list in order
* to implement best effort round robin. To do this, we need to reset
* the pxIndex to point to the tail again. */
pxReadyTasksLists[ uxCurPriority ].pxIndex = ( ListItem_t * ) &( pxReadyTasksLists[ uxCurPriority ].xListEnd );
uxListRemove( &( pxTCBCur->xStateListItem ) );
vListInsertEnd( &( pxReadyTasksLists[ uxCurPriority ] ), &( pxTCBCur->xStateListItem ) );
break;
get_next_task:
/* The current task cannot be scheduled. Get the next task in the list */
listGET_OWNER_OF_NEXT_ENTRY( pxTCBCur, &( pxReadyTasksLists[ uxCurPriority ] ) );
} while( pxTCBCur != pxTCBFirst); /* Check to see if we've walked the entire list */
}
assert( xTaskScheduled == pdTRUE ); /* At this point, a task MUST have been scheduled */
}
#endif /* configUSE_PORT_OPTIMISED_TASK_SELECTION */
void vTaskSwitchContext( void )
{
//Theoretically, this is only called from either the tick interrupt or the crosscore interrupt, so disabling
//interrupts shouldn't be necessary anymore. Still, for safety we'll leave it in for now.
int irqstate=portENTER_CRITICAL_NESTED();
/* vTaskSwitchContext is called either from:
* - ISR dispatcher when return from an ISR (interrupts will already be disabled)
* - vTaskSuspend() which is not in a critical section
* Therefore, we enter a critical section ISR version to ensure safety */
taskENTER_CRITICAL_ISR( &xTaskQueueMutex );
if( uxSchedulerSuspended[ xPortGetCoreID() ] != ( UBaseType_t ) pdFALSE )
{
@@ -3278,7 +3353,6 @@ void vTaskSwitchContext( void )
overflows. The guard against negative values is to protect
against suspect run time stat counter implementations - which
are provided by the application, not the kernel. */
taskENTER_CRITICAL_ISR(&xTaskQueueMutex);
if( ulTotalRunTime > ulTaskSwitchedInTime[ xPortGetCoreID() ] )
{
pxCurrentTCB[ xPortGetCoreID() ]->ulRunTimeCounter += ( ulTotalRunTime - ulTaskSwitchedInTime[ xPortGetCoreID() ] );
@@ -3287,7 +3361,6 @@ void vTaskSwitchContext( void )
{
mtCOVERAGE_TEST_MARKER();
}
taskEXIT_CRITICAL_ISR(&xTaskQueueMutex);
ulTaskSwitchedInTime[ xPortGetCoreID() ] = ulTotalRunTime;
}
#endif /* configGENERATE_RUN_TIME_STATS */
@@ -3296,123 +3369,17 @@ void vTaskSwitchContext( void )
taskFIRST_CHECK_FOR_STACK_OVERFLOW();
taskSECOND_CHECK_FOR_STACK_OVERFLOW();
/* Select a new task to run */
/*
We cannot do taskENTER_CRITICAL_ISR(&xTaskQueueMutex); here because it saves the interrupt context to the task tcb, and we're
swapping that out here. Instead, we're going to do the work here ourselves. Because interrupts are already disabled, we only
need to acquire the mutex.
*/
vPortCPUAcquireMutex( &xTaskQueueMutex );
#if !configUSE_PORT_OPTIMISED_TASK_SELECTION
unsigned portBASE_TYPE foundNonExecutingWaiter = pdFALSE, ableToSchedule = pdFALSE, resetListHead;
unsigned portBASE_TYPE holdTop=pdFALSE;
tskTCB * pxTCB;
portBASE_TYPE uxDynamicTopReady = uxTopReadyPriority;
/*
* ToDo: This scheduler doesn't correctly implement the round-robin scheduling as done in the single-core
* FreeRTOS stack when multiple tasks have the same priority and are all ready; it just keeps grabbing the
* first one. ToDo: fix this.
* (Is this still true? if any, there's the issue with one core skipping over the processes for the other
* core, potentially not giving the skipped-over processes any time.)
*/
while ( ableToSchedule == pdFALSE && uxDynamicTopReady >= 0 )
{
resetListHead = pdFALSE;
// Nothing to do for empty lists
if (!listLIST_IS_EMPTY( &( pxReadyTasksLists[ uxDynamicTopReady ] ) )) {
ableToSchedule = pdFALSE;
tskTCB * pxRefTCB;
/* Remember the current list item so that we
can detect if all items have been inspected.
Once this happens, we move on to a lower
priority list (assuming nothing is suitable
for scheduling). Note: This can return NULL if
the list index is at the listItem */
pxRefTCB = pxReadyTasksLists[ uxDynamicTopReady ].pxIndex->pvOwner;
if ((void*)pxReadyTasksLists[ uxDynamicTopReady ].pxIndex==(void*)&pxReadyTasksLists[ uxDynamicTopReady ].xListEnd) {
//pxIndex points to the list end marker. Skip that and just get the next item.
listGET_OWNER_OF_NEXT_ENTRY( pxRefTCB, &( pxReadyTasksLists[ uxDynamicTopReady ] ) );
}
do {
listGET_OWNER_OF_NEXT_ENTRY( pxTCB, &( pxReadyTasksLists[ uxDynamicTopReady ] ) );
/* Find out if the next task in the list is
already being executed by another core */
foundNonExecutingWaiter = pdTRUE;
portBASE_TYPE i = 0;
for ( i=0; i<portNUM_PROCESSORS; i++ ) {
if (i == xPortGetCoreID()) {
continue;
} else if (pxCurrentTCB[i] == pxTCB) {
holdTop=pdTRUE; //keep this as the top prio, for the other CPU
foundNonExecutingWaiter = pdFALSE;
break;
}
}
if (foundNonExecutingWaiter == pdTRUE) {
/* If the task is not being executed
by another core and its affinity is
compatible with the current one,
prepare it to be swapped in */
if (pxTCB->xCoreID == tskNO_AFFINITY) {
pxCurrentTCB[xPortGetCoreID()] = pxTCB;
ableToSchedule = pdTRUE;
} else if (pxTCB->xCoreID == xPortGetCoreID()) {
pxCurrentTCB[xPortGetCoreID()] = pxTCB;
ableToSchedule = pdTRUE;
} else {
ableToSchedule = pdFALSE;
holdTop=pdTRUE; //keep this as the top prio, for the other CPU
}
} else {
ableToSchedule = pdFALSE;
}
if (ableToSchedule == pdFALSE) {
resetListHead = pdTRUE;
} else if ((ableToSchedule == pdTRUE) && (resetListHead == pdTRUE)) {
tskTCB * pxResetTCB;
do {
listGET_OWNER_OF_NEXT_ENTRY( pxResetTCB, &( pxReadyTasksLists[ uxDynamicTopReady ] ) );
} while(pxResetTCB != pxRefTCB);
}
} while ((ableToSchedule == pdFALSE) && (pxTCB != pxRefTCB));
} else {
if (!holdTop) --uxTopReadyPriority;
}
--uxDynamicTopReady;
}
#else
//For Unicore targets we can keep the current FreeRTOS O(1)
//Scheduler. I hope to optimize better the scheduler for
//Multicore settings -- This will involve to create a per
//affinity ready task list which will impact hugely on
//tasks module
taskSELECT_HIGHEST_PRIORITY_TASK();
#endif
/* Select a new task to run using either the generic C or port
optimised asm code. */
taskSELECT_HIGHEST_PRIORITY_TASK(); /*lint !e9079 void * is used as this macro is used with timers and co-routines too. Alignment is known to be fine as the type of the pointer stored and retrieved is the same. */
traceTASK_SWITCHED_IN();
xSwitchingContext[ xPortGetCoreID() ] = pdFALSE;
//Exit critical region manually as well: release the mux now, interrupts will be re-enabled when we
//exit the function.
vPortCPUReleaseMutex( &xTaskQueueMutex );
xSwitchingContext[ xPortGetCoreID() ] = pdFALSE;
#if CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK
vPortSetStackWatchpoint(pxCurrentTCB[xPortGetCoreID()]->pxStack);
#endif
}
portEXIT_CRITICAL_NESTED(irqstate);
taskEXIT_CRITICAL_ISR( &xTaskQueueMutex );
}
/*-----------------------------------------------------------*/