The new Simple SMP Scheduler allocates a processor for the processor
count highest priority ready threads. The thread priority and position
in the ready chain are the only information to determine the scheduling
decision. Threads with an allocated processor are in the scheduled
chain. After initialization the scheduled chain has exactly processor
count nodes. Each processor has exactly one allocated thread after
initialization. All enqueue and extract operations may exchange threads
with the scheduled chain. One thread will be added and another will be
removed. The scheduled and ready chain is ordered according to the
thread priority order. The chain insert operations are O(count of ready
threads), thus this scheduler is unsuitable for most real-time
applications.
The thread preempt mode will be ignored.
Add and use _Scheduler_simple_Insert_priority_fifo_order(),
_Scheduler_simple_Insert_priority_lifo_order(),
_Scheduler_simple_Insert_priority_fifo() and
_Scheduler_simple_Insert_priority_lifo().
The yielding thread of the yield operation is now specified by a
parameter. The tick operation may be performed for each executing
thread in a SMP configuration.
Rename in rtems_smp_get_processor_count(). Always provide
<rtems/score/smp.h> and <rtems/rtems/smp.h>. Add
_SMP_Get_processor_count(). This function will be a compile time
constant defined to be one on uni-processor configurations. This allows
iterations over all processors without overhead on uni-processor
configurations.
Delete _Thread_Evaluate_is_dispatch_needed().
Use _Thread_Dispatch_is_enabled() in rtems_task_mode() instead of the
system state to determine if a thread dispatch is allowed. Signales are
now delivered in rtems_task_mode() even if preemption is disabled. This
is in line with rtems_signal_send().
Use interrupt disable/enable to protect the complete refill state
change. This avoids race conditions for the task driven configuration
and a later SMP support.
Add and use _Objects_Put_without_thread_dispatch(). These two functions
pair with the _Objects_Get() function. This helps to introduce object
specific SMP locks to avoid lock contention.
Move thread dispatch declarations and inline functions to new header
<rtems/score/threaddispatch.h> to make it independent of the
Thread_Control structure. This avoids a cyclic dependency in case
thread dispatch functions are used for the object implementation.
