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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: edf.h,v 1.5 2004-05-17 15:03:50 anton Exp $

 File:        $File$

 Revision:    $Revision: 1.5 $

 Last update: $Date: 2004-05-17 15:03:50 $

 ------------

 This file contains the scheduling module EDF (Earliest Deadline First)

 Title:

   EDF (Earliest Deadline First)

 Task Models Accepted:

   HARD_TASK_MODEL - Hard Tasks (Periodic and Sporadic)

     wcet field and mit field must be != 0. They are used to set the wcet

       and period of the tasks.

     periodicity field can be either PERIODIC or APERIODIC

     drel field must be <= mit. NOTE: a drel of 0 is interpreted as mit.

     offset field specifies a release offset relative to task_activate or

       group_activate.

 Guest Models Accepted:

   JOB_TASK_MODEL - a single guest task activation

     Identified by an absolute deadline and a period.

     period field is ignored

 Description:

   This module schedules periodic and sporadic tasks based on their

   absolute deadlines. The task guarantee is based on a simple

   utilization approach. The utilization factor of a task is computed

   as wcet/drel. (By default, drel = mit.) A periodic task must only

   be activated once; subsequent activations are triggered by an

   internal timer. By contrast, an sporadic task must be explicitely

   activated for each instance. NO GUARANTEE is performed on guest

   tasks. The guarantee must be performed by the level that inserts

   guest tasks in the EDF level.

 Exceptions raised:

   XUNVALID_GUEST

     This level doesn't support guests. When a guest operation

     is called, the exception is raised.

   The following exceptions may be raised by the module:

   XDEADLINE_MISS

     If a task misses its deadline and the EDF_ENABLE_DL_EXCEPTION

     flag is set, this exception is raised.

   XWCET_VIOLATION

     If a task executes longer than its declared wcet and the

     EDF_ENABLE_WCET_EXCEPTION flag is set, this exception is raised.

   XACTIVATION

     If a sporadic task is activated more often than its declared mit

     and the EDF_ENABLE_ACT_EXCEPTION flag is set, this exception is

     raised. This exception is also raised if a periodic task is

     activated while not in the SLEEP state.

 Restrictions & special features:

   - Relative deadlines drel <= mit may be specified.

   - An offset > 0 will delay the activation of the task by the same

     amount of time. To synchronize a group of tasks, use the

     group_activate function.

   - This level doesn't manage the main task.

   - The level uses the priority and timespec_priority fields.

   - A function to return the used bandwidth of a level is provided.

   - The guest tasks don't provide the guest_endcycle function

   - At init time, the user can specify the behavior in case of

     deadline and wcet overruns. The following flags are available:

     (No flags enabled)      - Deadline and wcet overruns are ignored.

                               Pending periodic jobs are queued and are

                               eventually scheduled with correct deadlines

                               according to their original arrival times.

                               Sporadic tasks that arrive to often are

                               simply dropped.

     EDF_ENABLE_DL_CHECK     - When a deadline overrun occurs, the

                               dl_miss counter of the task is increased.

                               Same behavior for pending jobs as above.

     EDF_ENABLE_WCET_CHECK   - When a wcet overrun occurs, the

                               wcet_miss counter of the task is increased.

                               Same behavior for pending jobs as above.

     EDF_ENABLE_DL_EXCEPTION - When a deadline overrun occurs, an

                               exception is raised.

     EDF_ENABLE_WCET_EXCEPTION - When a wcet overrun occurs, an

                               exception is raised.

     EDF_ENABLE_ACT_EXCEPTION  When a periodic or sporadic task is activated

                               too often, an exception is raised.

   - The functions EDF_get_dl_miss, EDF_get_wcet_miss, EDF_get_nact,

     and EDF_get_nskip can be used to find out the number of missed

     deadlines, number of wcet overruns, number of currently queued

     periodic activations, and the number of skipped sporadic activations.

**/

/*

 * 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 __EDF_H__

#define __EDF_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 EDF_DISABLE_ALL            0

#define EDF_ENABLE_GUARANTEE       1  /*+ Task guarantee enabled       +*/

#define EDF_ENABLE_WCET_CHECK      2  /*+ Wcet monitoring enabled      +*/

#define EDF_ENABLE_DL_CHECK        4  /*+ Deadline monitoring enabled  +*/

#define EDF_ENABLE_WCET_EXCEPTION  8  /*+ Wcet overrun exception enabled +*/

#define EDF_ENABLE_DL_EXCEPTION   16  /*+ Deadline overrun exception enabled +*/

#define EDF_ENABLE_ACT_EXCEPTION  32  /*+ Activation exception enabled +*/

#define EDF_ENABLE_ALL            63  /*+ All flags enabled            +*/

/*+ Registration function +*/

LEVEL EDF_register_level(int flags);

/*+ Returns the used bandwidth of a level +*/

bandwidth_t EDF_usedbandwidth(LEVEL l);

int EDF_get_dl_miss(PID p);

int EDF_get_wcet_miss(PID p);

int EDF_get_nact(PID p);

int EDF_get_nskip(PID p);

__END_DECLS

#endif