static Thread_Control *_Scheduler_priority_SMP_Get_highest_ready(
Scheduler_SMP_Control *self
)
{
Thread_Control *highest_ready = NULL;
if ( !_Priority_bit_map_Is_empty() ) {
highest_ready = _Scheduler_priority_Ready_queue_first( &self->ready[ 0 ] );
}
return highest_ready;
}
static Scheduler_Node *_Scheduler_priority_SMP_Get_highest_ready(
Scheduler_Context *context,
Scheduler_Node *node
)
{
Scheduler_priority_SMP_Context *self =
_Scheduler_priority_SMP_Get_self( context );
(void) node;
return (Scheduler_Node *) _Scheduler_priority_Ready_queue_first(
&self->Bit_map,
&self->Ready[ 0 ]
);
}
/*
* This method is unique to this scheduler because it takes into
* account affinity as it determines the highest ready thread.
* Since this is used to pick a new thread to replace the victim,
* the highest ready thread must have affinity such that it can
* be executed on the victim's processor.
*/
static Scheduler_Node *_Scheduler_priority_affinity_SMP_Get_highest_ready(
Scheduler_Context *context,
Scheduler_Node *victim
)
{
Scheduler_priority_SMP_Context *self =
_Scheduler_priority_SMP_Get_self( context );
Priority_Control index;
Scheduler_Node *highest = NULL;
Thread_Control *victim_thread;
uint32_t victim_cpu_index;
Scheduler_priority_affinity_SMP_Node *node;
/*
* This is done when we need to check if reevaluations are needed.
*/
if ( victim == NULL ) {
node = (Scheduler_priority_affinity_SMP_Node *)
_Scheduler_priority_Ready_queue_first(
&self->Bit_map,
&self->Ready[ 0 ]
);
return &node->Base.Base.Base;
}
victim_thread = _Scheduler_Node_get_owner( victim );
victim_cpu_index = _Per_CPU_Get_index( _Thread_Get_CPU( victim_thread ) );
/**
* @todo The deterministic priority scheduler structure is optimized
* for insertion, extraction, and finding the highest priority
* thread. Scanning the list of ready threads is not a purpose
* for which it was optimized. There are optimizations to be
* made in this loop.
*
* + by checking the major bit, we could potentially skip entire
* groups of 16.
*
* When using this scheduler as implemented, the application's
* choice of numeric priorities and their distribution can have
* an impact on performance.
*/
for ( index = _Priority_bit_map_Get_highest( &self->Bit_map ) ;
index <= PRIORITY_MAXIMUM;
index++ )
{
Chain_Control *chain = &self->Ready[index];
Chain_Node *chain_node;
for ( chain_node = _Chain_First( chain );
chain_node != _Chain_Immutable_tail( chain ) ;
chain_node = _Chain_Next( chain_node ) )
{
node = (Scheduler_priority_affinity_SMP_Node *) chain_node;
/*
* Can this thread run on this CPU?
*/
if ( CPU_ISSET( (int) victim_cpu_index, node->Affinity.set ) ) {
highest = &node->Base.Base.Base;
break;
}
}
if ( highest )
break;
}
_Assert( highest != NULL );
return highest;
}
