mlqueue.cxx

eCos1.31版

//==========================================================================
//
//      sched/mlqueue.cxx
//
//      Multi-level queue scheduler class implementation
//
//==========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    nickg
// Contributors: nickg, jlarmour
// Date:         1999-02-17
// Purpose:      Multilevel queue scheduler class implementation
// Description:  This file contains the implementations of
//               Cyg_Scheduler_Implementation and
//               Cyg_SchedThread_Implementation.
//              
//
//####DESCRIPTIONEND####
//
//==========================================================================

#include <pkgconf/kernel.h>

#include <cyg/kernel/ktypes.h>         // base kernel types
#include <cyg/infra/cyg_trac.h>        // tracing macros
#include <cyg/infra/cyg_ass.h>         // assertion macros

#include <cyg/kernel/sched.hxx>        // our header

#include <cyg/hal/hal_arch.h>          // Architecture specific definitions

#include <cyg/kernel/thread.inl>       // thread inlines
#include <cyg/kernel/sched.inl>        // scheduler inlines

#ifdef CYGSEM_KERNEL_SCHED_MLQUEUE

//-------------------------------------------------------------------------
// Some local tracing control - a default.
#ifdef CYGDBG_USE_TRACING
# if !defined( CYGDBG_INFRA_DEBUG_TRACE_ASSERT_SIMPLE ) && \
     !defined( CYGDBG_INFRA_DEBUG_TRACE_ASSERT_FANCY  )
   // ie. not a tracing implementation that takes a long time to output

#  ifndef CYGDBG_KERNEL_TRACE_TIMESLICE
#   define CYGDBG_KERNEL_TRACE_TIMESLICE
#  endif // control not already defined

# endif  // trace implementation not ..._SIMPLE && not ..._FANCY
#endif   // CYGDBG_USE_TRACING

//==========================================================================
// Cyg_Scheduler_Implementation class static members

#ifdef CYGSEM_KERNEL_SCHED_TIMESLICE

cyg_ucount32 Cyg_Scheduler_Implementation::timeslice_count =
                                        CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS;

#endif


//==========================================================================
// Cyg_Scheduler_Implementation class members

// -------------------------------------------------------------------------
// Constructor.

Cyg_Scheduler_Implementation::Cyg_Scheduler_Implementation()
{
    CYG_REPORT_FUNCTION();
        
    queue_map   = 0;

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// Choose the best thread to run next

Cyg_Thread *
Cyg_Scheduler_Implementation::schedule(void)
{
    CYG_REPORT_FUNCTYPE("returning thread %08x");

    // The run queue may _never_ be empty, there is always
    // an idle thread at the lowest priority.

    CYG_ASSERT( queue_map != 0, "Run queue empty");
    CYG_ASSERT( queue_map & (1<<CYG_THREAD_MIN_PRIORITY), "Idle thread vanished!!!");
    CYG_ASSERT( !run_queue[CYG_THREAD_MIN_PRIORITY].empty(), "Idle thread vanished!!!");
    
    register cyg_uint32 index;

    HAL_LSBIT_INDEX(index, queue_map);

    Cyg_Thread *thread = run_queue[index].highpri();

    CYG_ASSERT( thread != NULL , "No threads in run queue");

    CYG_REPORT_RETVAL(thread);

    return thread;
}

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

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

    cyg_priority pri                            = thread->priority;
    Cyg_ThreadQueue_Implementation *queue       = &run_queue[pri];

    CYG_ASSERT((CYG_THREAD_MIN_PRIORITY >= pri) 
               && (CYG_THREAD_MAX_PRIORITY <= pri),
               "Priority out of range!");

    // If the thread is on some other queue, remove it
    // here.
    if( thread->queue != NULL )
    {
        thread->queue->remove(thread);
        thread->queue = NULL;
    }
    
    if( queue->empty() )
    {
        // set the map bit and ask for a reschedule if this is a
        // new highest priority thread.
      
        queue_map |= (1<<pri);

        // If the new thread is higher priority than the
        // current thread, request a reschedule.

        if( pri < Cyg_Scheduler::get_current_thread()->priority )
            need_reschedule = true;
        
    }
    // else the queue already has an occupant, queue behind him

    CYG_ASSERT( queue_map != 0, "Run queue empty");
    CYG_ASSERT( queue_map & (1<<pri), "Queue map bit not set for pri");
    CYG_ASSERT( queue_map & (1<<CYG_THREAD_MIN_PRIORITY), "Idle thread vanished!!!");
//    CYG_ASSERT( !run_queue[CYG_THREAD_MIN_PRIORITY].empty(), "Idle thread vanished!!!");
    
    queue->enqueue(thread);
    
    CYG_REPORT_RETURN();
}

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

void
Cyg_Scheduler_Implementation::rem_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("thread=%08x", thread);
        
    CYG_ASSERT( queue_map != 0, "Run queue empty");
      
    cyg_priority pri                            = thread->priority;
    Cyg_ThreadQueue_Implementation *queue       = &run_queue[pri];

    CYG_ASSERT( pri != CYG_THREAD_MIN_PRIORITY, "Idle thread trying to sleep!");
    CYG_ASSERT( queue_map & (1<<pri), "Queue map bit not set for pri");
    CYG_ASSERT( !run_queue[CYG_THREAD_MIN_PRIORITY].empty(), "Idle thread vanished!!!");
    
    // remove thread from queue
    queue->remove(thread);

    if( queue->empty() )
    {
        // If this was only thread in
        // queue, clear map.
      
        queue_map &= ~(1<<pri);
    }

    CYG_ASSERT( queue_map != 0, "Run queue empty");
    CYG_ASSERT( queue_map & (1<<CYG_THREAD_MIN_PRIORITY), "Idle thread vanished!!!");
    CYG_ASSERT( !run_queue[CYG_THREAD_MIN_PRIORITY].empty(), "Idle thread vanished!!!");

    CYG_REPORT_RETURN();
}

// -------------------------------------------------------------------------
// register thread with scheduler

void
Cyg_Scheduler_Implementation::register_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("thread=%08x", thread);
    // No registration necessary in this scheduler
    CYG_REPORT_RETURN();
}

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

// deregister thread
void
Cyg_Scheduler_Implementation::deregister_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();
    CYG_REPORT_FUNCARG1("thread=%08x", thread);
    // No registration necessary in this scheduler    
    CYG_REPORT_RETURN();
}
    
// -------------------------------------------------------------------------
// Test the given priority for uniqueness

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
    CYG_ASSERT( queue_map != 0, "Run queue empty");
    CYG_ASSERT( queue_map & (1<<CYG_THREAD_MIN_PRIORITY), "Idle thread vanished!!!");
    
    if( --timeslice_count == 0 )
    {
        CYG_INSTRUMENT_SCHED(TIMESLICE,0,0);
#ifdef CYGDBG_KERNEL_TRACE_TIMESLICE
        CYG_TRACE0( true, "quantum consumed, time to reschedule" );
#endif
        // And force the current thread to yield.
        current_thread->yield();
    }

    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
}

#endif

//==========================================================================
// Cyg_Cyg_SchedThread_Implementation class members

Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation
(
    CYG_ADDRWORD sched_info
)
{