source: rtems/cpukit/score/include/rtems/score/schedulersimplesmp.h @ 7e119990

4.115
Last change on this file since 7e119990 was 5c3d250, checked in by Sebastian Huber <sebastian.huber@…>, on 07/04/14 at 12:34:23

score: Implement scheduler helping protocol

The following scheduler operations return a thread in need for help

  • unblock,
  • change priority, and
  • yield.

A thread in need for help is a thread that encounters a scheduler state
change from scheduled to ready or a thread that cannot be scheduled in
an unblock operation. Such a thread can ask threads which depend on
resources owned by this thread for help.

Add a new ask for help scheduler operation. This operation is used by
_Scheduler_Ask_for_help() to help threads in need for help returned by
the operations mentioned above. This operation is also used by
_Scheduler_Thread_change_resource_root() in case the root of a resource
sub-tree changes. A use case is the ownership change of a resource.

In case it is not possible to schedule a thread in need for help, then
the corresponding scheduler node will be placed into the set of ready
scheduler nodes of the scheduler instance. Once a state change from
ready to scheduled happens for this scheduler node it may be used to
schedule the thread in need for help.

  • Property mode set to 100644
File size: 3.5 KB
Line 
1/**
2 * @file
3 *
4 * @brief Simple SMP Scheduler API
5 *
6 * @ingroup ScoreSchedulerSMPSimple
7 */
8
9/*
10 *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
11 *
12 *  Copyright (c) 2013 embedded brains GmbH.
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.org/license/LICENSE.
17 */
18
19#ifndef _RTEMS_SCORE_SCHEDULERSIMPLE_SMP_H
20#define _RTEMS_SCORE_SCHEDULERSIMPLE_SMP_H
21
22#ifdef __cplusplus
23extern "C" {
24#endif
25
26#include <rtems/score/scheduler.h>
27#include <rtems/score/schedulerpriority.h>
28#include <rtems/score/schedulersmp.h>
29
30/**
31 * @defgroup ScoreSchedulerSMPSimple Simple Priority SMP Scheduler
32 *
33 * @ingroup ScoreSchedulerSMP
34 *
35 * The Simple Priority SMP Scheduler allocates a processor for the processor
36 * count highest priority ready threads.  The thread priority and position in
37 * the ready chain are the only information to determine the scheduling
38 * decision.  Threads with an allocated processor are in the scheduled chain.
39 * After initialization the scheduled chain has exactly processor count nodes.
40 * Each processor has exactly one allocated thread after initialization.  All
41 * enqueue and extract operations may exchange threads with the scheduled
42 * chain.  One thread will be added and another will be removed.  The scheduled
43 * and ready chain is ordered according to the thread priority order.  The
44 * chain insert operations are O(count of ready threads), thus this scheduler
45 * is unsuitable for most real-time applications.
46 *
47 * The thread preempt mode will be ignored.
48 *
49 * @{
50 */
51
52typedef struct {
53  Scheduler_SMP_Context Base;
54  Chain_Control         Ready;
55} Scheduler_simple_SMP_Context;
56
57/**
58 * @brief Entry points for the Simple SMP Scheduler.
59 */
60#define SCHEDULER_SIMPLE_SMP_ENTRY_POINTS \
61  { \
62    _Scheduler_simple_SMP_Initialize, \
63    _Scheduler_default_Schedule, \
64    _Scheduler_simple_SMP_Yield, \
65    _Scheduler_simple_SMP_Block, \
66    _Scheduler_simple_SMP_Unblock, \
67    _Scheduler_simple_SMP_Change_priority, \
68    _Scheduler_simple_SMP_Ask_for_help, \
69    _Scheduler_simple_SMP_Node_initialize, \
70    _Scheduler_default_Node_destroy, \
71    _Scheduler_simple_SMP_Update_priority, \
72    _Scheduler_priority_Priority_compare, \
73    _Scheduler_default_Release_job, \
74    _Scheduler_default_Tick, \
75    _Scheduler_SMP_Start_idle \
76    SCHEDULER_OPERATION_DEFAULT_GET_SET_AFFINITY \
77  }
78
79void _Scheduler_simple_SMP_Initialize( const Scheduler_Control *scheduler );
80
81void _Scheduler_simple_SMP_Node_initialize(
82  const Scheduler_Control *scheduler,
83  Thread_Control          *the_thread
84);
85
86void _Scheduler_simple_SMP_Block(
87  const Scheduler_Control *scheduler,
88  Thread_Control *thread
89);
90
91Thread_Control *_Scheduler_simple_SMP_Unblock(
92  const Scheduler_Control *scheduler,
93  Thread_Control *thread
94);
95
96Thread_Control *_Scheduler_simple_SMP_Change_priority(
97  const Scheduler_Control *scheduler,
98  Thread_Control          *the_thread,
99  Priority_Control         new_priority,
100  bool                     prepend_it
101);
102
103Thread_Control *_Scheduler_simple_SMP_Ask_for_help(
104  const Scheduler_Control *scheduler,
105  Thread_Control          *offers_help,
106  Thread_Control          *needs_help
107);
108
109void _Scheduler_simple_SMP_Update_priority(
110  const Scheduler_Control *scheduler,
111  Thread_Control          *thread,
112  Priority_Control         new_priority
113);
114
115Thread_Control *_Scheduler_simple_SMP_Yield(
116  const Scheduler_Control *scheduler,
117  Thread_Control *thread
118);
119
120/** @} */
121
122#ifdef __cplusplus
123}
124#endif
125
126#endif
127/* end of include file */
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