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/*
* Project: S.Ha.R.K.
*
* Coordinators:
* Giorgio Buttazzo <giorgio@sssup.it>
* Paolo Gai <pj@gandalf.sssup.it>
*
* Authors :
* Paolo Gai <pj@gandalf.sssup.it>
* Massimiliano Giorgi <massy@gandalf.sssup.it>
* Luca Abeni <luca@gandalf.sssup.it>
* (see the web pages for full authors list)
*
* ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
*
* http://www.sssup.it
* http://retis.sssup.it
* http://shark.sssup.it
*/
/**
------------
CVS : $Id: cbs.h,v 1.1.1.1 2002-03-29 14:12:51 pj Exp $
File: $File$
Revision: $Revision: 1.1.1.1 $
Last update: $Date: 2002-03-29 14:12:51 $
------------
This file contains the aperiodic server CBS (Total Bandwidth Server)
Title:
CBS (Constant Bandwidth Server)
Task Models Accepted:
SOFT_TASK_MODEL - Soft Tasks
wcet field is ignored
met field must be != 0
period field must be != 0
periodicity field can be either PERIODIC or APERIODIC
arrivals field can be either SAVE or SKIP
Description:
This module schedule his tasks following the CBS scheme.
(see Luca Abeni and Giorgio Buttazzo,
"Integrating Multimedia Applications in Hard Real-Time Systems"
Proceedings of the IEEE Real-Time Systems Symposium, Madrid, Spain,
December 1998)
The tasks are inserted in an EDF level (or similar) with a JOB_TASK_MODEL,
and the CBS level expects that the task is scheduled with the absolute
deadline passed in the model.
The task guarantee is based on the factor utilization approach.
Exceptions raised:
XUNVALID_GUEST
This level doesn't support guests. When a guest operation
is called, the exception is raised.
These exceptions are pclass-dependent...
XDEADLINE_MISS
If a task miss his deadline, the exception is raised.
Normally, a CBS task can't cause the raise of such exception because
if it really use more time than declared the deadline is postponed.
Restrictions & special features:
- This level doesn't manage the main task.
- At init time we have to specify:
. guarantee check
(when all task are created the system will check that the task_set
will not use more than the available bandwidth)
- A function to return the used bandwidth of the level is provided.
- A function to return the pending activations of the task.
**/
/*
* Copyright (C) 2000 Paolo Gai
*
* 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 __CBS_H__
#define __CBS_H__
#include <ll/ll.h>
#include <kernel/config.h>
#include <sys/types.h>
#include <kernel/types.h>
#include <modules/codes.h>
/*+ flags... +*/
#define CBS_DISABLE_ALL 0 /*+ Task Guarantee enabled +*/
#define CBS_ENABLE_GUARANTEE 1 /*+ Task Guarantee enabled +*/
#define CBS_ENABLE_ALL 1
#define CBS_FAILED_GUARANTEE 8 /*+ used in the module, unsettable
in EDF_register_level... +*/
/*+ Registration function:
int flags Options to be used in this level instance...
LEVEL master the level that must be used as master level for the
CBS tasks
+*/
void CBS_register_level(int flags, LEVEL master);
/*+ Returns the used bandwidth of a level +*/
bandwidth_t CBS_usedbandwidth(LEVEL l);
/*+ Returns the number of pending activations of a task.
No control is done if the task is not a CBS task! +*/
int CBS_get_nact(LEVEL l, PID p);
#endif