/**
* @file rtems/score/scheduleredf.h
*
* @brief Data Related to the Manipulation of Threads for the EDF Scheduler
*
* This include file contains all the constants and structures associated
* with the manipulation of threads for the EDF scheduler.
*/
/*
* Copryight (c) 2011 Petr Benes.
* Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifndef _RTEMS_SCORE_SCHEDULEREDF_H
#define _RTEMS_SCORE_SCHEDULEREDF_H
#include <rtems/score/priority.h>
#include <rtems/score/scheduler.h>
#include <rtems/score/schedulerpriority.h>
#include <rtems/score/rbtree.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup ScoreSchedulerEDF EDF Scheduler
*
* @ingroup ScoreScheduler
*/
/**@{*/
#define SCHEDULER_EDF_MAXIMUM_PRIORITY 255
/**
* Entry points for the Earliest Deadline First Scheduler.
*/
#define SCHEDULER_EDF_ENTRY_POINTS \
{ \
_Scheduler_EDF_Initialize, /* initialize entry point */ \
_Scheduler_EDF_Schedule, /* schedule entry point */ \
_Scheduler_EDF_Yield, /* yield entry point */ \
_Scheduler_EDF_Block, /* block entry point */ \
_Scheduler_EDF_Unblock, /* unblock entry point */ \
_Scheduler_EDF_Change_priority, /* change priority entry point */ \
_Scheduler_EDF_Map_priority, /* map priority entry point */ \
_Scheduler_EDF_Unmap_priority, /* unmap priority entry point */ \
SCHEDULER_OPERATION_DEFAULT_ASK_FOR_HELP \
_Scheduler_EDF_Node_initialize, /* node initialize entry point */ \
_Scheduler_default_Node_destroy, /* node destroy entry point */ \
_Scheduler_EDF_Update_priority, /* update priority entry point */ \
_Scheduler_EDF_Release_job, /* new period of task */ \
_Scheduler_default_Tick, /* tick entry point */ \
_Scheduler_default_Start_idle /* start idle entry point */ \
SCHEDULER_OPERATION_DEFAULT_GET_SET_AFFINITY \
}
/**
* This is just a most significant bit of Priority_Control type. It
* distinguishes threads which are deadline driven (priority
* represented by a lower number than @a SCHEDULER_EDF_PRIO_MSB) from those
* ones who do not have any deadlines and thus are considered background
* tasks.
*/
#define SCHEDULER_EDF_PRIO_MSB 0x80000000
typedef struct {
/**
* @brief Basic scheduler context.
*/
Scheduler_Context Base;
/**
* Top of the ready queue.
*/
RBTree_Control Ready;
} Scheduler_EDF_Context;
/**
* @typedef Scheduler_EDF_Queue_state
*
* This enumeration distiguishes state of a thread with respect to the
* ready queue.
*/
typedef enum {
SCHEDULER_EDF_QUEUE_STATE_NOT_PRESENTLY,
SCHEDULER_EDF_QUEUE_STATE_YES,
SCHEDULER_EDF_QUEUE_STATE_NEVER_HAS_BEEN
} Scheduler_EDF_Queue_state;
/**
* @brief Scheduler node specialization for EDF schedulers.
*/
typedef struct {
/**
* @brief Basic scheduler node.
*/
Scheduler_Node Base;
/**
* Pointer to corresponding Thread Control Block.
*/
Thread_Control *thread;
/**
* Rbtree node related to this thread.
*/
RBTree_Node Node;
/**
* State of the thread with respect to ready queue.
*/
Scheduler_EDF_Queue_state queue_state;
} Scheduler_EDF_Node;
/**
* @brief Initialize EDF scheduler.
*
* This routine initializes the EDF scheduler.
*
* @param[in] scheduler The scheduler instance.
*/
void _Scheduler_EDF_Initialize( const Scheduler_Control *scheduler );
/**
* @brief Removes thread from ready queue.
*
* This routine removes @a the_thread from the scheduling decision,
* that is, removes it from the ready queue. It performs
* any necessary scheduling operations including the selection of
* a new heir thread.
*
* @param[in] scheduler The scheduler instance.
* @param[in] the_thread is the thread to be blocked.
*/
void _Scheduler_EDF_Block(
const Scheduler_Control *scheduler,
Thread_Control *the_thread
);
/**
* @brief Sets the heir thread to be the next ready thread
* in the rbtree ready queue.
*
* This kernel routine sets the heir thread to be the next ready thread
* in the rbtree ready queue.
*
* @param[in] scheduler The scheduler instance.
* @param[in] the_thread being scheduled.
*/
void _Scheduler_EDF_Schedule(
const Scheduler_Control *scheduler,
Thread_Control *the_thread
);
/**
* @brief Initializes an EDF specific scheduler node of @a the_thread.
*
* @param[in] scheduler The scheduler instance.
* @param[in] the_thread being initialized.
*/
void _Scheduler_EDF_Node_initialize(
const Scheduler_Control *scheduler,
Thread_Control *the_thread
);
/**
* @brief Updates position in the ready queue of @a the_thread.
*
* This routine updates position in the ready queue of @a the_thread.
*
* @param[in] scheduler The scheduler instance.
* @param[in] the_thread will have its scheduler specific information
* structure updated.
* @param[in] new_priority is the desired new priority.
*/
void _Scheduler_EDF_Update_priority(
const Scheduler_Control *scheduler,
Thread_Control *the_thread,
Priority_Control new_priority
);
/**
* @brief Adds @a the_thread to the scheduling decision.
*
* This routine adds @a the_thread to the scheduling decision, that is,
* adds it to the ready queue and updates any appropriate scheduling
* variables, for example the heir thread.
*
* @param[in] scheduler The scheduler instance.
* @param[in] the_thread will be unblocked.
*/
Scheduler_Void_or_thread _Scheduler_EDF_Unblock(
const Scheduler_Control *scheduler,
Thread_Control *the_thread
);
Scheduler_Void_or_thread _Scheduler_EDF_Change_priority(
const Scheduler_Control *scheduler,
Thread_Control *the_thread,
Priority_Control new_priority,
bool prepend_it
);
Priority_Control _Scheduler_EDF_Map_priority(
const Scheduler_Control *scheduler,
Priority_Control priority
);
Priority_Control _Scheduler_EDF_Unmap_priority(
const Scheduler_Control *scheduler,
Priority_Control priority
);
/**
* @brief invoked when a thread wishes to voluntarily
* transfer control of the processor to another thread
* with equal deadline.
*
* This routine is invoked when a thread wishes to voluntarily
* transfer control of the processor to another thread in the queue with
* equal deadline. This does not have to happen very often.
*
* This routine will remove the specified THREAD from the ready queue
* and place it back. The rbtree ready queue is responsible for FIFO ordering
* in such a case.
*
* @param[in] scheduler The scheduler instance.
* @param[in,out] the_thread The yielding thread.
*/
Scheduler_Void_or_thread _Scheduler_EDF_Yield(
const Scheduler_Control *scheduler,
Thread_Control *the_thread
);
/**
* @brief Called when a new job of task is released.
*
* This routine is called when a new job of task is released.
* It is called only from Rate Monotonic manager in the beginning
* of new period.
*
* @param[in] scheduler The scheduler instance.
* @param[in] the_thread is the owner of the job.
* @param[in] deadline of the new job from now. If equal to 0,
* the job was cancelled or deleted, thus a running task
* has to be suspended.
*/
void _Scheduler_EDF_Release_job (
const Scheduler_Control *scheduler,
Thread_Control *the_thread,
uint32_t deadline
);
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
