159 lines
4.8 KiB
C
159 lines
4.8 KiB
C
/* Copyright (C) 2004 David Decotigny
|
|
|
|
This program is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU General Public License
|
|
as published by the Free Software Foundation; either version 2
|
|
of the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
|
|
USA.
|
|
*/
|
|
#ifndef _SOS_SCHED_H_
|
|
#define _SOS_SCHED_H_
|
|
|
|
|
|
/**
|
|
* @file sched.h
|
|
*
|
|
* A basic scheduler inspired from the O(1) Linux scheduler. Supports
|
|
* 2 classes of thread priorities:
|
|
* - so-called 'real-time' threads scheduled according to a simple
|
|
* traditional static priority real-time scheduler. "Real-time" round
|
|
* robin scheduling is not supported.
|
|
* - "fair" time-sharing scheduling for non real-time threads. "fair"
|
|
* because no starvation among the non real-time threads is
|
|
* possible. Contrary to the original O(1) Linux scheduler, the
|
|
* on-line adjustment of the scheduling priorities to cope with
|
|
* interactive/non interactive threads discrimination is not
|
|
* supported: threads keep having the same priority as long as the
|
|
* user does not change it.
|
|
*
|
|
* The functions below manage CPU queues, and are NEVER responsible
|
|
* for context switches (see thread.h for that) or synchronizations
|
|
* (see kwaitq.h or the higher levels primitives [mutex, semaphore,
|
|
* ...] for that).
|
|
*
|
|
* @note IMPORTANT: all the functions below are meant to be called
|
|
* ONLY by the thread/timer/kwaitq subsystems. DO NOT use them
|
|
* directly from anywhere else: use ONLY the thread/kwaitq functions!
|
|
* If you still want to call them directly despite this disclaimer,
|
|
* simply disable interrupts before clling them.
|
|
*/
|
|
|
|
#include <sos/errno.h>
|
|
#include <sos/time.h>
|
|
|
|
|
|
/**
|
|
* The definition of a priority
|
|
*/
|
|
typedef unsigned char sos_sched_priority_t;
|
|
|
|
|
|
#include <sos/thread.h>
|
|
|
|
|
|
/**
|
|
* Valid priority interval ("real-time" and non real-time threads altogether)
|
|
*/
|
|
#define SOS_SCHED_PRIO_HIGHEST 0
|
|
#define SOS_SCHED_PRIO_LOWEST 63
|
|
#define SOS_SCHED_NUM_PRIO 64
|
|
|
|
|
|
/**
|
|
* Class-specific priorities
|
|
*/
|
|
#define SOS_SCHED_PRIO_RT_HIGHEST 0 /**< Highest 'real-time' static prio. */
|
|
#define SOS_SCHED_PRIO_RT_LOWEST 15 /**< Lowest 'real-time' static priority */
|
|
#define SOS_SCHED_PRIO_TS_HIGHEST 16 /**< Highest time-sharing priority */
|
|
#define SOS_SCHED_PRIO_TS_LOWEST 63 /**< Lowest time-sharing priority */
|
|
|
|
#define SOS_SCHED_PRIO_DEFAULT 40 /**< Default priority */
|
|
|
|
|
|
/**
|
|
* Helper macros (Yes, priorities ordered in decreasing numerical value)
|
|
*
|
|
* @note: The use of this function is RESERVED
|
|
*/
|
|
#define SOS_SCHED_PRIO_CMP(prio1,prio2) ((prio1) - (prio2))
|
|
|
|
#define SOS_SCHED_PRIO_IS_VALID(prio) \
|
|
({ int __prio = (int)(prio); \
|
|
((__prio) <= SOS_SCHED_PRIO_LOWEST) \
|
|
&& \
|
|
((__prio) >= SOS_SCHED_PRIO_HIGHEST); })
|
|
|
|
#define SOS_SCHED_PRIO_IS_RT(prio) \
|
|
({ int __prio = (int)(prio); \
|
|
((__prio) <= SOS_SCHED_PRIO_RT_LOWEST) \
|
|
&& \
|
|
((__prio) >= SOS_SCHED_PRIO_RT_HIGHEST); })
|
|
|
|
|
|
/**
|
|
* The time slices for 'time-sharing' user threads, in ms
|
|
*/
|
|
#define SOS_TIME_SLICE_MIN 10 /* for SOS_SCHED_PRIO_TS_HIGHEST */
|
|
#define SOS_TIME_SLICE_MAX 200 /* for SOS_SCHED_PRIO_TS_LOWEST */
|
|
|
|
|
|
/**
|
|
* Initialize the scheduler
|
|
*
|
|
* @note: The use of this function is RESERVED
|
|
*/
|
|
sos_ret_t sos_sched_subsystem_setup(void);
|
|
|
|
|
|
/**
|
|
* Mark the given thread as ready
|
|
*
|
|
* @note: The use of this function is RESERVED
|
|
*/
|
|
sos_ret_t sos_sched_set_ready(struct sos_thread * thr);
|
|
|
|
|
|
/**
|
|
* Return the identifier of the next thread to run. Also removes it
|
|
* from the ready list, but does NOT set is as current_thread !
|
|
*
|
|
* @param current_thread TCB of the thread calling the function
|
|
*
|
|
* @param do_yield When TRUE, put the current executing thread at the
|
|
* end of the ready list. Otherwise it is kept at the head of it.
|
|
*
|
|
* @note: The use of this function is RESERVED
|
|
*/
|
|
struct sos_thread * sos_reschedule(struct sos_thread * current_thread,
|
|
sos_bool_t do_yield);
|
|
|
|
/**
|
|
* Called by thread subsystem each time a READY thread's priority is
|
|
* changed
|
|
*
|
|
* @note: The use of this function is RESERVED (to thread.c)
|
|
*/
|
|
sos_ret_t sos_sched_change_priority(struct sos_thread * thr,
|
|
sos_sched_priority_t priority);
|
|
|
|
|
|
/**
|
|
* Account for the execution of a time tick. Should be called
|
|
* immediately before the timer ISR calls sos_reschedule() before
|
|
* returning to thread context.
|
|
*
|
|
* @note The use of this function is RESERVED (to timer IRQ)
|
|
*/
|
|
sos_ret_t sos_sched_do_timer_tick(void);
|
|
|
|
#endif /* _SOS_WAITQUEUE_H_ */
|