WebSVN - shark - Blame - Rev 159 - /shark/trunk/include/modules/edf.h

Rev	Author	Line No.	Line
2	pj	1	/*
		2	* Project: S.Ha.R.K.
		3	*
		4	* Coordinators:
		5	* Giorgio Buttazzo <giorgio@sssup.it>
		6	* Paolo Gai <pj@gandalf.sssup.it>
		7	*
		8	* Authors :
		9	* Paolo Gai <pj@gandalf.sssup.it>
		10	* Massimiliano Giorgi <massy@gandalf.sssup.it>
		11	* Luca Abeni <luca@gandalf.sssup.it>
		12	* (see the web pages for full authors list)
		13	*
		14	* ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
		15	*
		16	* http://www.sssup.it
		17	* http://retis.sssup.it
		18	* http://shark.sssup.it
		19	*/
		20
		21
		22	/**
		23	------------
159	pj	24	CVS : $Id: edf.h,v 1.4 2003-05-05 07:31:12 pj Exp $
2	pj	25
		26	File: $File$
159	pj	27	Revision: $Revision: 1.4 $
		28	Last update: $Date: 2003-05-05 07:31:12 $
2	pj	29	------------
		30
		31	This file contains the scheduling module EDF (Earliest Deadline First)
		32
		33	Title:
		34	EDF (Earliest Deadline First)
		35
		36	Task Models Accepted:
		37	HARD_TASK_MODEL - Hard Tasks (Periodic and Sporadic)
		38	wcet field and mit field must be != 0. They are used to set the wcet
		39	and period of the tasks.
		40	periodicity field can be either PERIODIC or APERIODIC
		41	drel field is ignored
		42
		43	Guest Models Accepted:
		44	JOB_TASK_MODEL - a single guest task activation
		45	Identified by an absolute deadline and a period.
		46	period field is ignored
		47
		48	Description:
		49	This module schedule his tasks following the classic EDF scheme.
		50	The task guarantee is based on the factor utilization approach.
		51	The tasks scheduled are periodic and sporadic. The sporadic tasks
		52	are like hard task with periodicity set to APERIODIC; they are guaranteed
		53	as a periodic task with period equal to the minimum interarrival time.
		54	All the task are put in a queue and the scheduling is based on the
		55	deadline value.
		56	NO GUARANTEE is performed on guest tasks. The guarantee must be performed
		57	by the level that inserts guest tasks in the EDF level.
		58
		59	Exceptions raised:
		60	XUNVALID_GUEST
		61	This level doesn't support guests. When a guest operation
		62	is called, the exception is raised.
		63
		64	These exceptions are pclass-dependent...
		65	XDEADLINE_MISS
		66	If a task miss his deadline, the exception is raised.
		67
		68	XWCET_VIOLATION
		69	If a task doesn't end the current cycle before if consume the wcet,
		70	an exception is raised, and the task is put in the EDF_WCET_VIOLATED
		71	state. To reactivate it, use EDF_task_activate via task_activate or
		72	manage directly the EDF data structure. Note that the exception is not
		73	handled properly, an XDEADLINE_MISS exeeption will also be raised at
		74	the period end...
		75
		76	XACTIVATION
		77	If a sporadic task is activated with a rate that is greather than the
		78	rate declared in the model, this exception is raised and the task is NOT
		79	activated.
		80	This exception is also raised if we are trying to activate a periodic task
		81	stopped with task_sleep before the deadline in which the task_sleep is
		82	called.
		83
		84	Restrictions & special features:
		85	- This level doesn't manage the main task.
		86	- At init time we can choose if the level have to activate
		87	. the wcet check
		88	(If a task require more time than declared, it is stopped and put in
		89	the state EDF_WCET_VIOLATED; a XWCET_VIOLATION exception is raised)
		90	. the task guarantee algorithm
		91	(when all task are created the system will check that the task_set
		92	will not use more than the available bandwidth)
		93	- The level use the priority and timespec_priority fields.
		94	- A function to return the used bandwidth of a level is provided.
		95	- The guest tasks don't provide the guest_endcycle function
		96
		97	**/
		98
		99	/*
		100	* Copyright (C) 2000 Paolo Gai
		101	*
		102	* This program is free software; you can redistribute it and/or modify
		103	* it under the terms of the GNU General Public License as published by
		104	* the Free Software Foundation; either version 2 of the License, or
		105	* (at your option) any later version.
		106	*
		107	* This program is distributed in the hope that it will be useful,
		108	* but WITHOUT ANY WARRANTY; without even the implied warranty of
		109	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		110	* GNU General Public License for more details.
		111	*
		112	* You should have received a copy of the GNU General Public License
		113	* along with this program; if not, write to the Free Software
		114	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		115	*
		116	*/
		117
		118
		119	#ifndef __EDF_H__
		120	#define __EDF_H__
		121
		122	#include <ll/ll.h>
		123	#include <kernel/config.h>
		124	#include <sys/types.h>
		125	#include <kernel/types.h>
80	pj	126	#include "ll/sys/cdefs.h"
2	pj	127
80	pj	128	__BEGIN_DECLS
2	pj	129
80	pj	130
2	pj	131	/+ flags... +/
		132	#define EDF_DISABLE_ALL 0
		133	#define EDF_ENABLE_WCET_CHECK 1 /+ Wcet check enabled +/
		134	#define EDF_ENABLE_GUARANTEE 2 /+ Task Guarantee enabled +/
		135	#define EDF_ENABLE_ALL 3 /+ All flags enabled +/
		136
		137
		138	/*+ Registration function:
38	pj	139	int flag Options to be used in this level instance...
2	pj	140
38	pj	141	returns the level number at which the module has been registered.
		142	+*/
		143	LEVEL EDF_register_level(int flag);
		144
2	pj	145	/+ Returns the used bandwidth of a level +/
		146	bandwidth_t EDF_usedbandwidth(LEVEL l);
		147
80	pj	148	__END_DECLS
2	pj	149	#endif

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