source: rtems/cpukit/score/include/rtems/score/scheduler.h @ 6eba7c85

4.115
Last change on this file since 6eba7c85 was 6eba7c85, checked in by Sebastian Huber <sebastian.huber@…>, on Jun 10, 2013 at 2:15:46 PM

scheduler: Specify thread of yield operation

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.

  • Property mode set to 100644
File size: 4.5 KB
Line 
1/**
2 *  @file  rtems/score/scheduler.h
3 *
4 *  @brief Constants and Structures Associated with the Scheduler
5 *
6 *  This include file contains all the constants and structures associated
7 *  with the scheduler.
8 */
9
10/*
11 *  Copyright (C) 2010 Gedare Bloom.
12 *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
13 *
14 *  The license and distribution terms for this file may be
15 *  found in the file LICENSE in this distribution or at
16 *  http://www.rtems.com/license/LICENSE.
17 */
18
19#ifndef _RTEMS_SCORE_SCHEDULER_H
20#define _RTEMS_SCORE_SCHEDULER_H
21
22#include <rtems/score/percpu.h>
23#include <rtems/score/chain.h>
24#include <rtems/score/priority.h>
25#include <rtems/score/prioritybitmap.h>
26
27#ifdef __cplusplus
28extern "C" {
29#endif
30
31/**
32 *  @defgroup ScoreScheduler Scheduler Handler
33 *
34 *  @ingroup Score
35 *
36 *  This handler encapsulates functionality related to managing sets of threads
37 *  that are ready for execution.
38 */
39/**@{*/
40
41/**
42 * function jump table that holds pointers to the functions that
43 * implement specific schedulers.
44 */
45typedef struct {
46  /** Implements the scheduling decision logic (policy). */
47  void ( *initialize )(void);
48
49  /** Implements the scheduling decision logic (policy). */
50  void ( *schedule )(void);
51
52  /**
53   * @brief Voluntarily yields the processor per the scheduling policy.
54   *
55   * @see _Scheduler_Yield().
56   */
57  void ( *yield )( Thread_Control *thread );
58
59  /** Removes the given thread from scheduling decisions. */
60  void ( *block )(Thread_Control *);
61
62  /** Adds the given thread to scheduling decisions. */
63  void ( *unblock )(Thread_Control *);
64
65  /** allocates the scheduler field of the given thread */
66  void * ( *allocate )(Thread_Control *);
67
68  /** frees the scheduler field of the given thread */
69  void ( *free )(Thread_Control *);
70
71  /** updates the scheduler field of the given thread -- primarily used
72   * when changing the thread's priority. */
73  void ( *update )(Thread_Control *);
74
75  /** enqueue a thread as the last of its priority group */
76  void ( *enqueue )(Thread_Control *);
77
78  /** enqueue a thread as the first of its priority group */
79  void ( *enqueue_first )(Thread_Control *);
80
81  /** extract a thread from the ready set */
82  void ( *extract )(Thread_Control *);
83
84  /**
85   * Compares two priorities (returns >0 for higher priority, 0 for equal
86   * and <0 for lower priority).
87   */
88  int ( *priority_compare )(Priority_Control, Priority_Control);
89
90  /** This routine is called upon release of a new job. */
91  void ( *release_job ) (Thread_Control *, uint32_t);
92
93  /** perform scheduler update actions required at each clock tick */
94  void ( *tick )(void);
95
96  /**
97   * @brief Starts the idle thread for a particular processor.
98   *
99   * @see _Scheduler_Start_idle().
100   */
101  void ( *start_idle )( Thread_Control *thread, Per_CPU_Control *processor );
102} Scheduler_Operations;
103
104/**
105 * This is the structure used to manage the scheduler.
106 */
107typedef struct {
108  /**
109   *  This points to the data structure used to manage the ready set of
110   *  tasks. The pointer varies based upon the type of
111   *  ready queue required by the scheduler.
112   */
113  void                   *information;
114
115  /** The jump table for scheduler-specific functions */
116  Scheduler_Operations    Operations;
117} Scheduler_Control;
118
119/**
120 *  The _Scheduler holds the structures used to manage the
121 *  scheduler.
122 *
123 * @note Can we make this per-cpu? then _Scheduler will be a macro.
124 *
125 * @note This is instantiated and initialized in confdefs.h.
126 */
127extern Scheduler_Control  _Scheduler;
128
129/**
130 * Macro testing whether @a p1 has lower priority than @a p2
131 * in the intuitive sense of priority.
132 */
133#define _Scheduler_Is_priority_lower_than( _p1, _p2 ) \
134  (_Scheduler_Priority_compare(_p1,_p2) < 0)
135
136/**
137 * Macro testing whether @a p1 has higher priority than @a p2
138 * in the intuitive sense of priority.
139 */
140#define _Scheduler_Is_priority_higher_than( _p1, _p2 ) \
141  (_Scheduler_Priority_compare(_p1,_p2) > 0)
142
143/**
144 *  @brief Initializes the scheduler to the policy chosen by the user.
145 *
146 *  This routine initializes the scheduler to the policy chosen by the user
147 *  through confdefs, or to the priority scheduler with ready chains by
148 *  default.
149 */
150void _Scheduler_Handler_initialization( void );
151
152/**
153 * @brief Unblocks the thread.
154 *
155 * @param[in/out] thread An idle thread.
156 * @param[in] processor This parameter is unused.
157 */
158void _Scheduler_default_Start_idle(
159  Thread_Control  *thread,
160  Per_CPU_Control *processor
161);
162
163#ifndef __RTEMS_APPLICATION__
164#include <rtems/score/scheduler.inl>
165#endif
166
167/**@}*/
168
169#ifdef __cplusplus
170}
171#endif
172
173#endif
174/* end of include file */
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