int sched_yield( void )
{
_Thread_Disable_dispatch();
_Scheduler_Yield( _Thread_Executing );
_Thread_Enable_dispatch();
return 0;
}
void _Scheduler_priority_Tick( void )
{
Thread_Control *executing;
executing = _Thread_Executing;
#ifdef __RTEMS_USE_TICKS_FOR_STATISTICS__
/*
* Increment the number of ticks this thread has been executing
*/
executing->cpu_time_used++;
#endif
/*
* If the thread is not preemptible or is not ready, then
* just return.
*/
if ( !executing->is_preemptible )
return;
if ( !_States_Is_ready( executing->current_state ) )
return;
/*
* The cpu budget algorithm determines what happens next.
*/
switch ( executing->budget_algorithm ) {
case THREAD_CPU_BUDGET_ALGORITHM_NONE:
break;
case THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE:
#if defined(RTEMS_SCORE_THREAD_ENABLE_EXHAUST_TIMESLICE)
case THREAD_CPU_BUDGET_ALGORITHM_EXHAUST_TIMESLICE:
#endif
if ( (int)(--executing->cpu_time_budget) <= 0 ) {
/*
* A yield performs the ready chain mechanics needed when
* resetting a timeslice. If no other thread's are ready
* at the priority of the currently executing thread, then the
* executing thread's timeslice is reset. Otherwise, the
* currently executing thread is placed at the rear of the
* FIFO for this priority and a new heir is selected.
*/
_Scheduler_Yield();
executing->cpu_time_budget = _Thread_Ticks_per_timeslice;
}
break;
#if defined(RTEMS_SCORE_THREAD_ENABLE_SCHEDULER_CALLOUT)
case THREAD_CPU_BUDGET_ALGORITHM_CALLOUT:
if ( --executing->cpu_time_budget == 0 )
(*executing->budget_callout)( executing );
break;
#endif
}
}
int nanosleep(
const struct timespec *rqtp,
struct timespec *rmtp
)
{
Watchdog_Interval ticks;
/*
* Return EINVAL if the delay interval is negative.
*
* NOTE: This behavior is beyond the POSIX specification.
* FSU and GNU/Linux pthreads shares this behavior.
*/
if ( !_Timespec_Is_valid( rqtp ) )
rtems_set_errno_and_return_minus_one( EINVAL );
ticks = _Timespec_To_ticks( rqtp );
/*
* A nanosleep for zero time is implemented as a yield.
* This behavior is also beyond the POSIX specification but is
* consistent with the RTEMS API and yields desirable behavior.
*/
if ( !ticks ) {
_Thread_Disable_dispatch();
_Scheduler_Yield();
_Thread_Enable_dispatch();
if ( rmtp ) {
rmtp->tv_sec = 0;
rmtp->tv_nsec = 0;
}
return 0;
}
/*
* Block for the desired amount of time
*/
_Thread_Disable_dispatch();
_Thread_Set_state(
_Thread_Executing,
STATES_DELAYING | STATES_INTERRUPTIBLE_BY_SIGNAL
);
_Watchdog_Initialize(
&_Thread_Executing->Timer,
_Thread_Delay_ended,
_Thread_Executing->Object.id,
NULL
);
_Watchdog_Insert_ticks( &_Thread_Executing->Timer, ticks );
_Thread_Enable_dispatch();
/* calculate time remaining */
if ( rmtp ) {
ticks -=
_Thread_Executing->Timer.stop_time - _Thread_Executing->Timer.start_time;
_Timespec_From_ticks( ticks, rmtp );
/*
* Only when POSIX is enabled, can a sleep be interrupted.
*/
#if defined(RTEMS_POSIX_API)
/*
* If there is time remaining, then we were interrupted by a signal.
*/
if ( ticks )
rtems_set_errno_and_return_minus_one( EINTR );
#endif
}
return 0;
}
