mlqueue.cxx

开放源码实时操作系统源码.

cyg_bool
Cyg_Scheduler_Implementation::unique( cyg_priority priority)
{
    CYG_REPORT_FUNCTYPE("returning %d");
    CYG_REPORT_FUNCARG1("priority=%d", priority);
    // Priorities are not unique
    CYG_REPORT_RETVAL(true);
    return true;
}

//==========================================================================
// Support for timeslicing option

#ifdef CYGSEM_KERNEL_SCHED_TIMESLICE

// -------------------------------------------------------------------------

void
Cyg_Scheduler_Implementation::timeslice(void)
{
#ifdef CYGDBG_KERNEL_TRACE_TIMESLICE
    CYG_REPORT_FUNCTION();
#endif

#ifdef CYGPKG_KERNEL_SMP_SUPPORT

    HAL_SMP_CPU_TYPE cpu;
    HAL_SMP_CPU_TYPE cpu_count = CYG_KERNEL_CPU_COUNT();
    HAL_SMP_CPU_TYPE cpu_this = CYG_KERNEL_CPU_THIS();
    
    for( cpu = 0; cpu < cpu_count; cpu++ )
    {
        if( --timeslice_count[cpu] == 0 )
            if( cpu == cpu_this )
                timeslice_cpu();
            else CYG_KERNEL_CPU_TIMESLICE_INTERRUPT( cpu, 0 );
    }

#else    

    if( --timeslice_count[CYG_KERNEL_CPU_THIS()] == 0 )
        timeslice_cpu();
    
#endif

#ifdef CYGDBG_KERNEL_TRACE_TIMESLICE
    CYG_REPORT_RETURN();
#endif    
}

// -------------------------------------------------------------------------

void
Cyg_Scheduler_Implementation::timeslice_cpu(void)
{
#ifdef CYGDBG_KERNEL_TRACE_TIMESLICE
    CYG_REPORT_FUNCTION();
#endif

    Cyg_Thread *thread = get_current_thread();
    HAL_SMP_CPU_TYPE cpu_this = CYG_KERNEL_CPU_THIS();
    
    CYG_ASSERT( queue_map != 0, "Run queue empty");
    CYG_ASSERT( queue_map & (1<<CYG_THREAD_MIN_PRIORITY), "Idle thread vanished!!!");

#ifdef CYGSEM_KERNEL_SCHED_TIMESLICE_ENABLE
    if( thread->timeslice_enabled &&
        timeslice_count[cpu_this] == 0 )
#else    
    if( timeslice_count[cpu_this] == 0 )
#endif
    {
        CYG_INSTRUMENT_SCHED(TIMESLICE,0,0);
#ifdef CYGDBG_KERNEL_TRACE_TIMESLICE
        CYG_TRACE0( true, "quantum consumed, time to reschedule" );
#endif

        CYG_ASSERT( get_sched_lock() > 0 , "Timeslice called with zero sched_lock");

        // Only try to rotate the run queue if the current thread is running.
        // Otherwise we are going to reschedule anyway.
        if( thread->get_state() == Cyg_Thread::RUNNING )
        {
            Cyg_Scheduler *sched = &Cyg_Scheduler::scheduler;

            CYG_INSTRUMENT_MLQ( TIMESLICE, thread, 0);
                
            CYG_ASSERTCLASS( thread, "Bad current thread");
            CYG_ASSERTCLASS( sched, "Bad scheduler");
    
            cyg_priority pri    = thread->priority;
            Cyg_RunQueue *queue = &sched->run_queue[pri];

#ifdef CYGPKG_KERNEL_SMP_SUPPORT

            // In SMP systems we set the head of the queue to point to
            // the thread immediately after the current
            // thread. schedule() will then pick that thread, or one
            // after it to run next.
            
            queue->to_head( thread->get_next() );
#else            
            queue->rotate();
#endif
            
            if( queue->get_head() != thread )
                sched->set_need_reschedule();

            timeslice_count[cpu_this] = CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS;
        }
    }

    
    CYG_ASSERT( queue_map & (1<<CYG_THREAD_MIN_PRIORITY), "Idle thread vanished!!!");
    CYG_ASSERT( !run_queue[CYG_THREAD_MIN_PRIORITY].empty(), "Idle thread vanished!!!");
#ifdef CYGDBG_KERNEL_TRACE_TIMESLICE
    CYG_REPORT_RETURN();
#endif
}

// -------------------------------------------------------------------------

__externC void cyg_scheduler_timeslice_cpu(void)
{
    Cyg_Scheduler::scheduler.timeslice_cpu();
}

#endif

//==========================================================================
// Cyg_SchedThread_Implementation class members

Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation
(
    CYG_ADDRWORD sched_info
)
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("sched_info=%08x", sched_info);
        
    // Set priority to the supplied value.
    priority = (cyg_priority)sched_info;

#ifdef CYGSEM_KERNEL_SCHED_TIMESLICE_ENABLE
    // If timeslice_enabled exists, set it true by default
    timeslice_enabled = true;
#endif
#ifdef CYGPKG_KERNEL_SMP_SUPPORT
    cpu = CYG_KERNEL_CPU_NONE;
#endif
    
    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Yield the processor to another thread

void
Cyg_SchedThread_Implementation::yield(void)
{
    CYG_REPORT_FUNCTION();
        
    // Prevent preemption
    Cyg_Scheduler::lock();

    Cyg_Thread *thread  = CYG_CLASSFROMBASE(Cyg_Thread,
                                            Cyg_SchedThread_Implementation,
                                            this);

    // Only do this if this thread is running. If it is not, there
    // is no point.
    
    if( thread->get_state() == Cyg_Thread::RUNNING )
    {
        // To yield we simply rotate the appropriate
        // run queue to the next thread and reschedule.

        CYG_INSTRUMENT_MLQ( YIELD, thread, 0);
        
        CYG_ASSERTCLASS( thread, "Bad current thread");
    
        Cyg_Scheduler *sched = &Cyg_Scheduler::scheduler;

        CYG_ASSERTCLASS( sched, "Bad scheduler");
    
        cyg_priority pri    = thread->priority;
        Cyg_RunQueue *queue = &sched->run_queue[pri];

#ifdef CYGPKG_KERNEL_SMP_SUPPORT

            // In SMP systems we set the head of the queue to point to
            // the thread immediately after the current
            // thread. schedule() will then pick that thread, or one
            // after it to run next.
            
            queue->to_head( thread->get_next() );
#else            
            queue->rotate();
#endif
        
        if( queue->get_head() != thread )
            sched->set_need_reschedule();
        else
        {
            // Reset the timeslice counter so that this thread gets a
            // full quantum as a reward for yielding when it is
            // eventually rescheduled.
            thread->timeslice_reset();
        }

    }
    
    // Unlock the scheduler and switch threads
#ifdef CYGDBG_USE_ASSERTS
    // This test keeps the assertions in unlock_inner() happy if
    // need_reschedule was not set above.
    if( !Cyg_Scheduler::get_need_reschedule() )
        Cyg_Scheduler::unlock();
    else 
#endif    
    Cyg_Scheduler::unlock_reschedule();

    
    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Rotate the run queue at a specified priority.
// (pri is the decider, not this, so the routine is static)

void
Cyg_SchedThread_Implementation::rotate_queue( cyg_priority pri )
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("priority=%d", pri);
        
    // Prevent preemption
    Cyg_Scheduler::lock();

    Cyg_Scheduler *sched = &Cyg_Scheduler::scheduler;

    CYG_ASSERTCLASS( sched, "Bad scheduler");
    
    Cyg_RunQueue *queue = &sched->run_queue[pri];

    if ( !queue->empty() ) {
        queue->rotate();
        sched->set_need_reschedule();
    }

    // Unlock the scheduler and switch threads
    Cyg_Scheduler::unlock();

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Move this thread to the head of its queue
// (not necessarily a scheduler queue)

void
Cyg_SchedThread_Implementation::to_queue_head( void )
{
    CYG_REPORT_FUNCTION();
        
    // Prevent preemption
    Cyg_Scheduler::lock();

    Cyg_Thread *thread  = CYG_CLASSFROMBASE(Cyg_Thread,
                                            Cyg_SchedThread_Implementation,
                                            this);

    CYG_ASSERTCLASS( thread, "Bad current thread");
    
    Cyg_ThreadQueue *q = thread->get_current_queue();
    if( q != NULL )
        q->to_head( thread );
    else if( thread->in_list() )
    {
        // If the queue pointer is NULL then it is on a run
        // queue. Move the thread to the head of it's priority list
        // and force a reschedule.
        
        Cyg_Scheduler *sched = &Cyg_Scheduler::scheduler;
        sched->run_queue[thread->priority].to_head( thread );
        sched->set_need_reschedule( thread );
    }

    // Unlock the scheduler and switch threads
    Cyg_Scheduler::unlock();

    CYG_REPORT_RETURN();
}

//==========================================================================
// Cyg_ThreadQueue_Implementation class members

// -------------------------------------------------------------------------        

void
Cyg_ThreadQueue_Implementation::enqueue(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("thread=%08x", thread);

    CYG_INSTRUMENT_MLQ( ENQUEUE, this, thread );
    
#ifdef CYGIMP_KERNEL_SCHED_SORTED_QUEUES

    // Insert the thread into the queue in priority order.

    Cyg_Thread *qhead = get_head();

    if( qhead == NULL ) add_tail( thread );
    else if( qhead == qhead->get_next() )
    {
        // There is currently only one thread in the queue, join it
        // and adjust the queue pointer to point to the highest
        // priority of the two. If they are the same priority,
        // leave the pointer pointing to the oldest.

        qhead->insert( thread );

        if( thread->priority < qhead->priority )
            to_head(thread);
    }
    else
    {
        // There is more than one thread in the queue. First check
        // whether we are of higher priority than the head and if
        // so just jump in at the front. Also check whether we are
        // lower priority than the tail and jump onto the end.
        // Otherwise we really have to search the queue to find
        // our place.

        if( thread->priority < qhead->priority )
        {
            qhead->insert( thread );
            to_head(thread);
        }
        else if( thread->priority > get_tail()->priority )
        {
            // We are lower priority than any thread in the queue,
            // go in at the end.

            add_tail( thread );
        }
        else
        {
            // Search the queue. We do this backwards so that we
            // always add new threads after any that have the same
            // priority.

            // Because of the previous tests we know that this
            // search will terminate before we hit the head of the
            // queue, hence we do not need to check for that
            // condition.
                
            Cyg_Thread *qtmp = get_tail();

            // Scan the queue until we find a higher or equal
            // priority thread.

            while( qtmp->priority > thread->priority )
                qtmp = qtmp->get_prev();

            // Append ourself after the node pointed to by qtmp.
                
            qtmp->append( thread );
        }
    }
#else
    // Just add the thread to the tail of the list
    add_tail( thread );
#endif
    
    thread->queue = CYG_CLASSFROMBASE(Cyg_ThreadQueue,
                                      Cyg_ThreadQueue_Implementation,
                                      this);
    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------

Cyg_Thread *
Cyg_ThreadQueue_Implementation::dequeue(void)
{
    CYG_REPORT_FUNCTYPE("returning thread %08x");
        
    Cyg_Thread *thread = rem_head();

    CYG_INSTRUMENT_MLQ( DEQUEUE, this, thread );
    
    if( thread != NULL )
        thread->queue = NULL;

    CYG_REPORT_RETVAL(thread);
    return thread;
}

// -------------------------------------------------------------------------

void
Cyg_ThreadQueue_Implementation::remove( Cyg_Thread *thread )
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("thread=%08x", thread);

    CYG_INSTRUMENT_MLQ( REMOVE, this, thread );
    
    thread->queue = NULL;

    Cyg_CList_T<Cyg_Thread>::remove( thread );

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------

Cyg_Thread *
Cyg_ThreadQueue_Implementation::highpri(void)
{
    CYG_REPORT_FUNCTYPE("returning thread %08x");
    CYG_REPORT_RETVAL(get_head());
    return get_head();
}

// -------------------------------------------------------------------------

inline void
Cyg_ThreadQueue_Implementation::set_thread_queue(Cyg_Thread *thread,
                                                 Cyg_ThreadQueue *tq )

{
    thread->queue = tq;
}

// -------------------------------------------------------------------------

#endif

// -------------------------------------------------------------------------
// EOF sched/mlqueue.cxx