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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>
* Giacomo Guidi <giacomo@gandalf.sssup.it>
*
* ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
*
* http://www.sssup.it
* http://retis.sssup.it
* http://shark.sssup.it
*/
/*
This file contains the aperiodic server CBS (Total Bandwidth Server)
with hard reservation and met/period update
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 __HCBS_H__
#define __HCBS_H__
#include <ll/ll.h>
#include <kernel/config.h>
#include <sys/types.h>
#include <kernel/types.h>
#include "ll/sys/cdefs.h"
__BEGIN_DECLS
/*+ flags... +*/
#define HCBS_DISABLE_ALL 0 /*+ Task Guarantee enabled +*/
#define HCBS_ENABLE_GUARANTEE 1 /*+ Task Guarantee enabled +*/
#define HCBS_ENABLE_ALL 1
#define HCBS_SET_PERIOD 0
#define HCBS_GET_PERIOD 1
#define HCBS_SET_MET 2
#define HCBS_GET_MET 3
typedef struct {
int command;
TIME param;
} HCBS_command_message;
/*+ 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
returns the level number at which the module has been registered.
+*/
LEVEL HCBS_register_level(int flags, LEVEL master);
/*+ Returns the used bandwidth of a level +*/
bandwidth_t HCBS_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 HCBS_get_nact(LEVEL l, PID p);
__END_DECLS
#endif