WebSVN - shark - Blame - Rev 1621 - /shark/branches/xen/modules/edf/edf/edf.h

Rev	Author	Line No.	Line
961	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	* Anton Cervin
		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	------------
		24	CVS : $Id: edf.h,v 1.1 2005-02-25 10:53:41 pj Exp $
		25
		26	File: $File$
		27	Revision: $Revision: 1.1 $
		28	Last update: $Date: 2005-02-25 10:53:41 $
		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 must be <= mit. NOTE 1: a drel of 0 is interpreted as mit.
		42	NOTE 2: The utilization of the task is computed as wcet/drel.
		43	offset field specifies a release offset relative to task_activate or
		44	group_activate.
		45
		46	Guest Models Accepted:
		47	JOB_TASK_MODEL - a single guest task activation
		48	Identified by an absolute deadline and a period.
		49	period field is ignored
		50
		51	Description:
		52	This module schedules periodic and sporadic tasks based on their
		53	absolute deadlines. The task guarantee is based on a simple
		54	utilization approach. The utilization factor of a task is computed
		55	as wcet/drel. (By default, drel = mit.) A periodic task must only
		56	be activated once; subsequent activations are triggered by an
		57	internal timer. By contrast, an sporadic task must be explicitely
		58	activated for each instance. NO GUARANTEE is performed on guest
		59	tasks. The guarantee must be performed by the level that inserts
		60	guest tasks in the EDF level.
		61
		62	Exceptions raised:
		63	XUNVALID_GUEST
		64	This level doesn't support guests of this type. When a guest
		65	operation is called, the exception is raised.
		66
		67	The following exceptions may be raised by the module:
		68	XDEADLINE_MISS
		69	If a task misses its deadline and the EDF_ENABLE_DL_EXCEPTION
		70	flag is set, this exception is raised.
		71
		72	XWCET_VIOLATION
		73	If a task executes longer than its declared wcet and the
		74	EDF_ENABLE_WCET_EXCEPTION flag is set, this exception is raised.
		75
		76	XACTIVATION
		77	If a sporadic task is activated more often than its declared mit
		78	and the EDF_ENABLE_ACT_EXCEPTION flag is set, this exception is
		79	raised. This exception is also raised if a periodic task is
		80	activated while not in the SLEEP state.
		81
		82	Restrictions & special features:
		83
		84	- Relative deadlines drel <= mit may be specified.
		85	- An offset > 0 will delay the activation of the task by the same
		86	amount of time. To synchronize a group of tasks, assign suitable
		87	offsets and then use the group_activate function.
		88	- This level doesn't manage the main task.
		89	- The level uses the priority and timespec_priority fields.
		90	- The guest tasks don't provide the guest_endcycle function.
		91	- At init time, the user can specify the behavior in case of
		92	deadline and wcet overruns. The following flags are available:
		93
		94	(No flags enabled) - Deadline and wcet overruns are ignored.
		95	Pending periodic jobs are queued and are
		96	eventually scheduled with correct deadlines
		97	according to their original arrival times.
		98	Sporadic tasks that arrive to often are
		99	simply dropped.
		100	EDF_ENABLE_DL_CHECK - When a deadline overrun occurs, the
		101	dl_miss counter of the task is increased.
		102	Same behavior for pending jobs as above.
		103	EDF_ENABLE_WCET_CHECK - When a wcet overrun occurs, the
		104	wcet_miss counter of the task is increased.
		105	Same behavior for pending jobs as above.
		106	EDF_ENABLE_DL_EXCEPTION - When a deadline overrun occurs, an
		107	exception is raised.
		108	EDF_ENABLE_WCET_EXCEPTION - When a wcet overrun occurs, an
		109	exception is raised.
		110	EDF_ENABLE_ACT_EXCEPTION When a periodic or sporadic task is activated
		111	too often, an exception is raised.
		112
		113	- The functions EDF_get_dl_miss, EDF_get_wcet_miss, EDF_get_act_miss,
		114	and EDF_get_nact can be used to find out the number of missed
		115	deadlines, the number of wcet overruns, the number of skipped
		116	activations, and the number of currently queued periodic activations.
		117
		118	**/
		119
		120	/*
		121	* Copyright (C) 2000 Paolo Gai
		122	*
		123	* This program is free software; you can redistribute it and/or modify
		124	* it under the terms of the GNU General Public License as published by
		125	* the Free Software Foundation; either version 2 of the License, or
		126	* (at your option) any later version.
		127	*
		128	* This program is distributed in the hope that it will be useful,
		129	* but WITHOUT ANY WARRANTY; without even the implied warranty of
		130	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		131	* GNU General Public License for more details.
		132	*
		133	* You should have received a copy of the GNU General Public License
		134	* along with this program; if not, write to the Free Software
		135	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		136	*
		137	*/
		138
		139
		140	#ifndef __EDF_H__
		141	#define __EDF_H__
		142
		143	#include <ll/ll.h>
		144	#include <kernel/config.h>
		145	#include <sys/types.h>
		146	#include <kernel/types.h>
1621	fabio	147	#include <arch/sys/cdefs.h>
961	pj	148
		149	__BEGIN_DECLS
		150
		151	/* Level flags */
		152	#define EDF_DISABLE_ALL 0
		153	#define EDF_ENABLE_GUARANTEE 1 /* Task guarantee enabled */
		154	#define EDF_ENABLE_WCET_CHECK 2 /* Wcet monitoring enabled */
		155	#define EDF_ENABLE_DL_CHECK 4 /* Deadline monitoring enabled */
		156	#define EDF_ENABLE_WCET_EXCEPTION 8 /* Wcet overrun exception enabled */
		157	#define EDF_ENABLE_DL_EXCEPTION 16 /* Deadline overrun exception enabled */
		158	#define EDF_ENABLE_ACT_EXCEPTION 32 /* Activation exception enabled */
		159	#define EDF_ENABLE_ALL 63 /* All flags enabled */
		160
		161	/* Registration function */
		162	LEVEL EDF_register_level(int flags);
		163
		164
		165	/** Public utility functions **/
		166
		167	/* Get the bandwidth used by the level */
		168	bandwidth_t EDF_usedbandwidth(LEVEL l);
		169
		170	/* Get the number of missed deadlines for a task */
		171	int EDF_get_dl_miss(PID p);
		172
		173	/* Get the number of execution overruns for a task */
		174	int EDF_get_wcet_miss(PID p);
		175
		176	/* Get the number of skipped activations for a task */
		177	int EDF_get_act_miss(PID p);
		178
		179	/* Get the current number of queued activations for a task */
		180	int EDF_get_nact(PID p);
		181
		182
		183	__END_DECLS
		184	#endif

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