source: trunk/kernel/kern/scheduler.h @ 416

Last change on this file since 416 was 416, checked in by alain, 7 years ago

Improve sys_exec.
File size: 6.4 KB
Line 
1/*
2 * scheduler.h - Core scheduler definition.
3 *
4 * Author    Alain Greiner (2016)
5 *
6 * Copyright (c) UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH.
9 *
10 * ALMOS-MKH is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-MKH is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#ifndef _SCHEDULER_H_
25#define _SCHEDULER_H_
26
27#include <hal_types.h>
28#include <list.h>
29#include <spinlock.h>
30
31/****  Forward declarations  ****/
32
33struct core_s;
34struct thread_s;
35
36/*********************************************************************************************
37 * This structure define the scheduler associated to a given core.
38 ********************************************************************************************/
39
40typedef struct scheduler_s
41{
42    spinlock_t        lock;            /*! readlock protecting lists of threads             */
43    uint16_t          u_threads_nr;    /*! total number of attached user threads            */
44    uint16_t          k_threads_nr;    /*! total number of attached kernel threads          */
45    list_entry_t      u_root;          /*! root of list of user threads                     */
46    list_entry_t      k_root;          /*! root of list of kernel threads                   */
47    list_entry_t    * u_last;          /*! pointer on list_entry for last executed k_thread */
48    list_entry_t    * k_last;          /*! pointer on list entry for last executed u_thread */
49    struct thread_s * idle;            /*! pointer on idle thread                           */
50    struct thread_s * current;         /*! pointer on current running thread                */
51    bool_t            req_ack_pending; /*! signal_handller must be called when true         */
52}
53scheduler_t;
54
55/*********************************************************************************************
56 *  This function initialises the scheduler for a given core.
57 ********************************************************************************************/ 
58void sched_init( struct core_s * core );
59
60/*********************************************************************************************
61 * This function register a new thread in a given core scheduler.
62 *********************************************************************************************
63 * @ core    : local pointer on the core descriptor.
64 * @ thread  : local pointer on the thread descriptor.
65 ********************************************************************************************/ 
66void sched_register_thread( struct core_s   * core,
67                            struct thread_s * thread );
68
69/*********************************************************************************************
70 * This function is the only method to make a context switch. It is called in cas of TICK,
71 * or when when a thread explicitely requires a scheduling.
72 * It handles the pending signals for all threads attached to the core running the calling
73 * thread, and calls the sched_select() function to select a new thread.
74 * The cause argument is only used for debug by the sched_display() function, and
75 * indicates the scheduling cause.
76 *********************************************************************************************
77 * @ cause    : character string defining the scheduling cause.
78 ********************************************************************************************/
79void sched_yield( char * cause );
80
81/*********************************************************************************************
82 * This function scan all threads attached to a given scheduler, and executes the relevant
83 * actions for pending THREAD_FLAG_REQ_ACK or THREAD_FLAG_REQ_DELETE requests.
84 * It is called in by the sched_yield() function, with IRQ disabled.
85 * - REQ_ACK : it checks that target thread is blocked, decrements the response counter
86 *   to acknowledge the client thread, and reset the pending request.
87 * - REQ_DELETE : it detach the target thread from parent if attached, detach it from
88 *   the process, remove it from scheduler, release memory allocated to thread descriptor,
89 *   and destroy the process descriptor it the target thread was the last thread.
90 *********************************************************************************************
91 * @ core    : local pointer on the core descriptor.
92 ********************************************************************************************/
93void sched_handle_requests( struct core_s * core );
94
95/*********************************************************************************************
96 * This function does NOT modify the scheduler state.
97 * It just select a thread in the list of attached threads, implementing the following
98 * three steps policy:
99 * 1) It scan the list of kernel threads, from the next thread after the last executed one,
100 *    and returns the first runnable found : not IDLE, not blocked, client queue not empty.
101 *    It can be the current thread.
102 * 2) If no kernel thread found, it scan the list of user thread, from the next thread after
103 *    the last executed one, and returns the first runable found : not blocked.
104 *    It can be the current thread.
105 * 3) If no runable thread found, it returns the idle thread.
106 *********************************************************************************************
107 * @ core    : local pointer on scheduler.
108 * @ returns pointer on selected thread descriptor
109 ********************************************************************************************/
110struct thread_s * sched_select( struct scheduler_s * sched );
111
112/*********************************************************************************************
113 * This function display the internal state of the local core identified by its <lid>.
114 *********************************************************************************************
115 * @ lid      : local index of target core.
116 ********************************************************************************************/
117void sched_display( lid_t lid );
118
119
120#endif  /* _SCHEDULER_H_ */
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