WebSVN - shark - Blame - Rev 80 - /shark/trunk/include/modules/tbs.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	------------
80	pj	24	CVS : $Id: tbs.h,v 1.3 2003-03-13 13:39:05 pj Exp $
2	pj	25
		26	File: $File$
80	pj	27	Revision: $Revision: 1.3 $
		28	Last update: $Date: 2003-03-13 13:39:05 $
2	pj	29	------------
		30
		31	This file contains the aperiodic server TBS (Total Bandwidth Server)
		32
		33	Title:
		34	TBS (Total Bandwidth Server)
		35
		36	Task Models Accepted:
		37	SOFT_TASK_MODEL - Aperiodic Tasks
		38	wcet field must be != 0
		39	met field is ignored
		40	period field is ignored
		41	periodicity must be APERIODIC
		42	arrivals can be either SAVE or SKIP
		43
		44	Description:
		45	This module schedule his tasks following the TBS scheme.
		46	Each task has a deadline assigned with the TBS scheme,
		47
		48	wcet
		49	d = max(r , d ) + ----
		50	k k k-1 Us
		51
		52	The tasks are inserted in an EDF level (or similar) with a JOB_TASK_MODEL,
		53	and the TBS level expects that the task is scheduled with the absolute
		54	deadline passed in the model.
		55
		56	The task guarantee is based on the factor utilization approach.
		57	The theory guarantees that the task set is schedulable if
		58	Up + Us <= 1
		59	so it is sufficient to add the Us to the bandwidth used by the upper
		60	levels (we suppose that the levels with level number < of the current
		61	can guarantee their task sets basing on the same formula...
		62
		63	All the tasks are put in a FIFO (FCFS) queue and at a time only the first
		64	task in the queue is put in the upper level.
		65
		66	Exceptions raised:
		67	XUNVALID_GUEST
		68	This level doesn't support guests. When a guest operation
		69	is called, the exception is raised.
		70
		71	These exceptions are pclass-dependent...
		72	XDEADLINE_MISS
		73	If a task miss his deadline, the exception is raised.
		74	Normally, a TBS task can't cause the raise of such exception because
		75	if it really use more time than declared a XWCET_VIOLATION is raised
		76	instead.
		77
		78	XWCET_VIOLATION
		79	If a task doesn't end the current cycle before if consume the wcet,
		80	an exception is raised, and the task is put in the TBS_WCET_VIOLATED
		81	state. To reactivate it, use TBS_task_activate via task_activate or
		82	manage directly the TBS data structure. Note that if the exception
		83	is not handled properly, an XDEADLINE_MISS exception will also be
		84	raised at the absolute deadline...
		85
		86	Restrictions & special features:
		87	- This level doesn't manage the main task.
		88	- At init time we have to specify:
		89	. The bandwidth used by the server
		90	. some flags
		91	. wcet check activated
		92	(If a task require more time than declared, it is stopped and put in
		93	the state TBS_WCET_VIOLATED; a XWCET_VIOLATION exception is raised)
		94	. guarantee check
		95	(when all task are created the system will check that the task_set
		96	will not use more than the available bandwidth)
		97	- The level don't use the priority field.
		98	- A function to return the used bandwidth of the level is provided.
		99
		100	**/
		101
		102	/*
		103	* Copyright (C) 2000 Paolo Gai
		104	*
		105	* This program is free software; you can redistribute it and/or modify
		106	* it under the terms of the GNU General Public License as published by
		107	* the Free Software Foundation; either version 2 of the License, or
		108	* (at your option) any later version.
		109	*
		110	* This program is distributed in the hope that it will be useful,
		111	* but WITHOUT ANY WARRANTY; without even the implied warranty of
		112	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		113	* GNU General Public License for more details.
		114	*
		115	* You should have received a copy of the GNU General Public License
		116	* along with this program; if not, write to the Free Software
		117	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		118	*
		119	*/
		120
		121
		122	#ifndef __TBS_H__
		123	#define __TBS_H__
		124
		125	#include <ll/ll.h>
		126	#include <kernel/config.h>
		127	#include <sys/types.h>
		128	#include <kernel/types.h>
80	pj	129	#include "ll/sys/cdefs.h"
2	pj	130
80	pj	131	__BEGIN_DECLS
		132
2	pj	133	/+ flags... +/
		134	#define TBS_DISABLE_ALL 0
		135	#define TBS_ENABLE_WCET_CHECK 1 /+ Wcet check enabled +/
		136	#define TBS_ENABLE_GUARANTEE 2 /+ Task Guarantee enabled +/
		137	#define TBS_ENABLE_ALL 3 /+ All flags enabled +/
		138
		139
		140	/*+ Registration function:
		141	bandwidth_t b Max bandwidth used by the TBS
		142	int flags Options to be used in this level instance...
		143	LEVEL master the level that must be used as master level for the
		144	TBS tasks
		145	int num,den used to compute the TBS bandwidth +*/
		146	void TBS_register_level(int flags, LEVEL master, int num, int den);
		147
		148	/+ Returns the used bandwidth of a level +/
		149	bandwidth_t TBS_usedbandwidth(LEVEL l);
		150
		151	/*+ Returns the number of pending activations of a task, or -1 if the level
		152	is wrong.
		153	No control is done if the task is not a TBS task! +*/
		154	int TBS_get_nact(LEVEL l, PID p);
		155
80	pj	156	__END_DECLS
2	pj	157	#endif

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