Subversion Repositories shark

/*

 * Project: S.Ha.R.K.

 *

 * Coordinators: Giorgio Buttazzo <giorgio@sssup.it>

 *               Paolo Gai <pj@hartik.sssup.it>

 *

 * Authors     : Marco Caccamo and Paolo Gai

 *

 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)

 *

 * http://www.sssup.it

 * http://retis.sssup.it

 * http://shark.sssup.it

 */

/**

 ------------

 CVS :        $Id: cbs_ft.c,v 1.2 2002-10-28 08:14:58 pj Exp $

 File:        $File$

 Revision:    $Revision: 1.2 $

 Last update: $Date: 2002-10-28 08:14:58 $

 ------------

 This file contains the server CBS_FT

 Read CBS_FT.h for further details.

**/

/*

 * Copyright (C) 2000 Marco Caccamo and 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

 *

 */

#include "cbs_ft.h"

/*+ 4 debug purposes +*/

#undef CBS_FT_TEST

#ifdef TESTG

#include "drivers/glib.h"

TIME x,oldx;

extern TIME starttime;

#endif

/*+ Status used in the level +*/

#define CBS_FT_IDLE          APER_STATUS_BASE   /*+ waiting the activation +*/

#define CBS_FT_ZOMBIE        APER_STATUS_BASE+1 /*+ waiting the period end +*/

#define CBS_FT_DELAY         APER_STATUS_BASE+2 /*+ waiting the delay end  +*/

/* structure of an element of the capacity queue */  

struct cap_queue {

  int              cap;

  struct timespec  dead;

  struct cap_queue *next;

};  

/*+ the level redefinition for the CBS_FT level +*/

typedef struct {

  level_des l;     /*+ the standard level descriptor          +*/

  /* The wcet are stored in the task descriptor, but we need

     an array for the deadlines. We can't use the timespec_priority

     field because it is used by the master level!!!...

     Notice that however the use of the timespec_priority field

     does not cause any problem...                     */

  struct timespec cbs_ft_dline[MAX_PROC]; /*+ CBS_FT deadlines      +*/

  TIME period[MAX_PROC]; /*+ CBS_FT activation period            +*/

  int maxcap[MAX_PROC]; /* amount of capacity reserved to a primary+backup

                        couple */

  PID backup[MAX_PROC];  /* Backup task pointers, defined for primary tasks  */

  char CP[MAX_PROC];      /* checkpoint flag */

  char P_or_B[MAX_PROC];  /*  Type of task: PRIMARY or BACKUP */

  struct timespec reactivation_time[MAX_PROC];

        /*+ the time at witch  the reactivation timer is post +*/

  int reactivation_timer[MAX_PROC];  /*+ the recativation timer +*/

  struct cap_queue *queue;         /* pointer to the spare capacity queue */

  int flags;       /*+ the init flags...                      +*/

  bandwidth_t U;   /*+ the used bandwidth by the server       +*/

  int idle;         /* the idle flag...  */

  struct timespec start_idle; /*gives the start time of the last idle period */

  LEVEL scheduling_level;

} CBS_FT_level_des;

/* insert a capacity in the queue capacity ordering by deadline */

static int c_insert(struct timespec dead, int cap, struct cap_queue **que,

                     PID p)

{

  struct cap_queue *prev, *n, *new;

    prev = NULL;

    n = *que;

    while ((n != NULL) &&

           !TIMESPEC_A_LT_B(&dead, &n->dead)) {

        prev = n;

        n = n->next;

    }

    new = (struct cap_queue *)kern_alloc(sizeof(struct cap_queue));

    if (new == NULL) {

      kern_printf("\nNew cash_queue element failed\n");

      kern_raise(XINVALID_TASK, p);

      return -1;

    }

    new->next = NULL;

    new->cap = cap;

    new->dead = dead;

    if (prev != NULL)

      prev->next = new;

    else

      *que = new;

    if (n != NULL)

      new->next = n;

    return 0;

}

/* extract the first element from the capacity queue */

int c_extractfirst(struct cap_queue **que)

{

    struct cap_queue *p = *que;

    if (*que == NULL) return(-1);

    *que = (*que)->next;

    kern_free(p, sizeof(struct cap_queue));

    return(1);

}

/* read data of the first element from the capacity queue */

static void c_readfirst(struct timespec *d, int *c, struct cap_queue *que)

{

    *d = que->dead;

    *c = que->cap;

}

/* write data of the first element from the capacity queue */

static void c_writefirst(struct timespec dead, int cap, struct cap_queue *que)

{

    que->dead = dead;

    que->cap = cap;

}

static void CBS_FT_activation(CBS_FT_level_des *lev,

                             PID p,

                             struct timespec *acttime)

{

  JOB_TASK_MODEL job;

  int capacity;  

  /* This rule is used when we recharge the budget at initial task activation

     and each time a new task instance must be activated  */

  if (TIMESPEC_A_GT_B(acttime, &lev->cbs_ft_dline[p])) {

    /* we modify the deadline ... */

    TIMESPEC_ASSIGN(&lev->cbs_ft_dline[p], acttime);

  }

  if (proc_table[p].avail_time > 0)

    proc_table[p].avail_time = 0;

  /* A spare capacity is inserted in the capacity queue!! */

  ADDUSEC2TIMESPEC(lev->period[p], &lev->cbs_ft_dline[p]);

  capacity = lev->maxcap[p] - proc_table[ lev->backup[p] ].wcet;

  c_insert(lev->cbs_ft_dline[p], capacity, &lev->queue, p);

  /* it exploits available capacities from the capacity queue */

  while (proc_table[p].avail_time < proc_table[p].wcet &&

         lev->queue != NULL) {

    struct timespec dead;

    int             cap, delta;

    delta = proc_table[p].wcet - proc_table[p].avail_time;

    c_readfirst(&dead, &cap, lev->queue);

    if (!TIMESPEC_A_GT_B(&dead, &lev->cbs_ft_dline[p])) {

      if (cap > delta) {

        proc_table[p].avail_time += delta;

        c_writefirst(dead, cap - delta, lev->queue);

      }

      else {

        proc_table[p].avail_time += cap;

        c_extractfirst(&lev->queue);

      }

    }

    else

      break;

  }

  /* If the budget is still less than 0, an exception is raised */

  if (proc_table[p].avail_time <= 0) {

    kern_printf("\nnegative value for the budget!\n");

    kern_raise(XINVALID_TASK, p);

    return;

  }

  /*if (p==6)

    kern_printf("(act_time:%d  dead:%d av_time:%d)\n",

                acttime->tv_sec*1000000+

                acttime->tv_nsec/1000,

                lev->cbs_ft_dline[p].tv_sec*1000000+

                lev->cbs_ft_dline[p].tv_nsec/1000,

                proc_table[p].avail_time);  */

#ifdef TESTG

  if (starttime && p == 3) {

    oldx = x;

    x = ((lev->cbs_ft_dline[p].tv_sec*1000000+lev->cbs_ft_dline[p].tv_nsec/1000)/5000 - starttime) + 20;

    //      kern_printf("(a%d)",lev->cbs_ft_dline[p].tv_sec*1000000+lev->cbs_ft_dline[p].tv_nsec/1000);

    if (oldx > x) sys_end();

    if (x<640)

      grx_plot(x, 15, 8);

  }

#endif

  /* and, finally, we reinsert the task in the master level */

  job_task_default_model(job, lev->cbs_ft_dline[p]);

  job_task_def_yesexc(job);

  level_table[ lev->scheduling_level ]->

    guest_create(lev->scheduling_level, p, (TASK_MODEL *)&job);

  level_table[ lev->scheduling_level ]->

    guest_activate(lev->scheduling_level, p);

}

static char *CBS_FT_status_to_a(WORD status)

{

  if (status < MODULE_STATUS_BASE)

    return status_to_a(status);

  switch (status) {

    case CBS_FT_IDLE   : return "CBS_FT_Idle";

    case CBS_FT_ZOMBIE : return "CBS_FT_Zombie";

    case CBS_FT_DELAY  : return "CBS_FT_Delay";

    default         : return "CBS_FT_Unknown";

  }

}

/* this is the periodic reactivation of the task... */

static void CBS_FT_timer_reactivate(void *par)

{

  PID p = (PID) par;

  CBS_FT_level_des *lev;

  lev = (CBS_FT_level_des *)level_table[proc_table[p].task_level];

  if (proc_table[p].status == CBS_FT_IDLE) {

    /* the task has finished the current activation and must be

       reactivated */

    /* request_time represents the time of the last instance release!! */

    TIMESPEC_ASSIGN(&proc_table[p].request_time, &lev->reactivation_time[p]);

    /* If idle=1, then we have to discharge the capacities stored in

       the capacity queue up to the length of the idle interval */

    if (lev->idle == 1) {

      TIME interval;

      struct timespec delta;

      lev->idle = 0;

      SUBTIMESPEC(&proc_table[p].request_time, &lev->start_idle, &delta);

      /* length of the idle interval expressed in usec! */

      interval = TIMESPEC2NANOSEC(&delta) / 1000;

      /* it discharges the available capacities from the capacity queue */

      while (interval > 0 && lev->queue != NULL) {

        struct timespec dead;

        int             cap;

        c_readfirst(&dead, &cap, lev->queue);

        if (cap > interval) {

          c_writefirst(dead, cap - interval, lev->queue);

          interval = 0;

        }

        else {

          interval -= cap;

          c_extractfirst(&lev->queue);

        }      

      }

    }

    CBS_FT_activation(lev,p,&lev->reactivation_time[p]);

    /* Set the reactivation timer */

    TIMESPEC_ASSIGN(&lev->reactivation_time[p], &lev->cbs_ft_dline[p]);

    lev->reactivation_timer[p] = kern_event_post(&lev->reactivation_time[p],

                                                 CBS_FT_timer_reactivate,

                                                 (void *)p);

    event_need_reschedule();

  }

  else {

    /* this situation cannot occur */

    kern_printf("\nTrying to reactivate a primary task which is not IDLE!\n");

    kern_raise(XINVALID_TASK,p);

  }

}

static void CBS_FT_avail_time_check(CBS_FT_level_des *lev, PID p)

{

  /*+ if the capacity became negative the remaining computation time

    is diminuished.... +*/

  /* if (p==4)

    kern_printf("(old dead:%d av_time:%d)\n",

                lev->cbs_ft_dline[p].tv_sec*1000000+

                lev->cbs_ft_dline[p].tv_nsec/1000,

                proc_table[p].avail_time);  */

  int newcap = proc_table[p].wcet / 100 * 30;

  if (newcap <= 0)

    newcap = proc_table[p].wcet;

  /* it exploits available capacities from the capacity queue */

  while (proc_table[p].avail_time < newcap

         && lev->queue != NULL) {

    struct timespec dead;

    int             cap, delta;

    delta = newcap - proc_table[p].avail_time;

    c_readfirst(&dead, &cap, lev->queue);

    if (!TIMESPEC_A_GT_B(&dead, &lev->cbs_ft_dline[p])) {

      if (cap > delta) {

        proc_table[p].avail_time += delta;

        c_writefirst(dead, cap - delta, lev->queue);

      }

      else {

        proc_table[p].avail_time += cap;

        c_extractfirst(&lev->queue);

      }

    }

    else

      break;

  }

 /*if (p==6)

    kern_printf("(ATC dead:%d av_time:%d)\n",

                lev->cbs_ft_dline[p].tv_sec*1000000+

                lev->cbs_ft_dline[p].tv_nsec/1000,

                proc_table[p].avail_time);  */

  /* if the budget is still empty, the backup task must be woken up.

     Remind that a short chunk of primary will go ahead executing

     before the task switch occurs                                */

  if (proc_table[p].avail_time <= 0) {

    lev->CP[p] = 1;

    proc_table[p].avail_time += proc_table[ lev->backup[p] ].wcet;

  }

 /*if (p==6)

    kern_printf("(ATC1 dead:%d av_time:%d)\n",

                lev->cbs_ft_dline[p].tv_sec*1000000+

                lev->cbs_ft_dline[p].tv_nsec/1000,

                proc_table[p].avail_time);  */

}

/*+ this function is called when a killed or ended task reach the

  period end +*/

static void CBS_FT_timer_zombie(void *par)

{

  PID p = (PID) par;

  CBS_FT_level_des *lev;

  lev = (CBS_FT_level_des *)level_table[proc_table[p].task_level];

  /* we finally put the task in the FREE status */

  proc_table[p].status = FREE;

  q_insertfirst(p,&freedesc);

  /* and free the allocated bandwidth */

  lev->U -= (MAX_BANDWIDTH / lev->period[p]) * (TIME)lev->maxcap[p];

}

static int CBS_FT_level_accept_task_model(LEVEL l, TASK_MODEL *m)

{

  if (m->pclass == FT_PCLASS || m->pclass ==

      (FT_PCLASS | l)) {

    FT_TASK_MODEL *f = (FT_TASK_MODEL *) m;

    //kern_printf("accept :FAULT TOLERANT TASK found!!!!!!\n"); */

    if (f->type == PRIMARY && f->execP > 0 && f->budget < (int)f->period

        && f->backup != NIL) return 0;

    if (f->type == BACKUP && f->wcetB > 0)

      return 0;

  }

  return -1;

}

static int CBS_FT_level_accept_guest_model(LEVEL l, TASK_MODEL *m)

{

  return -1;

}

static char *onoff(int i)

{

  if (i)

    return "On ";

  else

    return "Off";

}

static void CBS_FT_level_status(LEVEL l)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  PID p;

  kern_printf("On-line guarantee : %s\n",

              onoff(lev->flags & CBS_FT_ENABLE_GUARANTEE));

  kern_printf("Used Bandwidth    : %u/%u\n",

              lev->U, MAX_BANDWIDTH);

  for (p=0; p<MAX_PROC; p++)

    if (proc_table[p].task_level == l && proc_table[p].status != FREE )

      kern_printf("Pid: %2d Name: %10s Period: %9ld Dline: %9ld.%6ld Stat: %s\n",

                  p,

                  proc_table[p].name,

                  lev->period[p],

                  lev->cbs_ft_dline[p].tv_sec,

                  lev->cbs_ft_dline[p].tv_nsec/1000,

                  CBS_FT_status_to_a(proc_table[p].status));

}

static PID CBS_FT_level_scheduler(LEVEL l)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  /* it stores the actual time and set the IDLE flag in order to handle

     the capacity queue discharging!!! */

  lev->idle = 1;

  ll_gettime(TIME_EXACT, &lev->start_idle);

  /* the CBS_FT don't schedule anything...

     it's an EDF level or similar that do it! */

  return NIL;

}

/* The on-line guarantee is enabled only if the appropriate flag is set... */

static int CBS_FT_level_guarantee(LEVEL l, bandwidth_t *freebandwidth)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  if (lev->flags & CBS_FT_FAILED_GUARANTEE) {

    *freebandwidth = 0;

    kern_printf("guarantee :garanzia fallita!!!!!!\n");

    return 0;

  }

  else if (*freebandwidth >= lev->U) {

    *freebandwidth -= lev->U;

    return 1;

  }

  else {

    kern_printf("guarantee :garanzia fallita per mancanza di banda!!!!!!\n");

    kern_printf("freeband: %d request band: %d", *freebandwidth, lev->U);

    return 0;

  }

}

static int CBS_FT_task_create(LEVEL l, PID p, TASK_MODEL *m)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  /* if the CBS_FT_task_create is called, then the pclass must be a

     valid pclass. */

  FT_TASK_MODEL *s = (FT_TASK_MODEL *)m;

  /* Enable budget check */

  proc_table[p].control |= CONTROL_CAP;  

  proc_table[p].avail_time = 0;

  NULL_TIMESPEC(&lev->cbs_ft_dline[p]);

  if (s->type == PRIMARY) {

    proc_table[p].wcet = (int)s->execP;

    lev->period[p] = s->period;

    lev->maxcap[p] = s->budget;

    lev->backup[p] = s->backup;

    lev->CP[p] = 0;

    lev->P_or_B[p] = PRIMARY;

    /* update the bandwidth... */

    if (lev->flags & CBS_FT_ENABLE_GUARANTEE) {

      bandwidth_t b;

      b = (MAX_BANDWIDTH / lev->period[p]) * (TIME)lev->maxcap[p];

      /* really update lev->U, checking an overflow... */

      if (MAX_BANDWIDTH - lev->U > b)

        lev->U += b;

      else

        /* The task can NOT be guaranteed (U>MAX_BANDWIDTH)...

           (see EDF.c) */

        lev->flags |= CBS_FT_FAILED_GUARANTEE;

    }

  }

  else {

    proc_table[p].wcet = (int)s->wcetB;

    lev->P_or_B[p] = BACKUP;

    /* Backup tasks are unkillable tasks! */

    proc_table[p].control |= NO_KILL;

  }

  return 0; /* OK, also if the task cannot be guaranteed... */

}

static void CBS_FT_task_detach(LEVEL l, PID p)

{

  /* the CBS_FT level doesn't introduce any dynamic allocated new field.

     we have only to reset the NO_GUARANTEE FIELD and decrement the allocated

     bandwidth */

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  if (lev->flags & CBS_FT_FAILED_GUARANTEE)

    lev->flags &= ~CBS_FT_FAILED_GUARANTEE;

  else

    lev->U -= (MAX_BANDWIDTH / lev->period[p]) * (TIME)lev->maxcap[p];

}

static int CBS_FT_task_eligible(LEVEL l, PID p)

{

  return 0; /* if the task p is chosen, it is always eligible */

}

#ifdef __TEST1__

  extern int testactive;

  extern struct timespec s_stime[];

  extern TIME s_curr[];

  extern TIME s_PID[];

  extern int useds;

#endif

static void CBS_FT_task_dispatch(LEVEL l, PID p, int nostop)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  level_table[ lev->scheduling_level ]->

    guest_dispatch(lev->scheduling_level,p,nostop);

#ifdef __TEST1__

  if (testactive)

    {

      TIMESPEC_ASSIGN(&s_stime[useds], &schedule_time);

      s_curr[useds] = proc_table[p].avail_time;

      s_PID[useds]  = p;

      useds++;

    }

#endif

}

static void CBS_FT_task_epilogue(LEVEL l, PID p)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  /* check if the budget is finished... */

  if (proc_table[p].avail_time <= 0) {

    /* A backup task cannot ever exhaust its budget! */

    if (lev->P_or_B[p] == BACKUP) {

      kern_printf("\nBACKUP wcet violation!\n");

      kern_raise(XWCET_VIOLATION,p);

      /* we kill the current activation */

      level_table[ lev->scheduling_level ]->

        guest_end(lev->scheduling_level, p);

      return;

    }

    /* we try to recharge the budget */

    CBS_FT_avail_time_check(lev, p);

    /* The budget must be greater than 0! */

    if (proc_table[p].avail_time <= 0) {

      kern_printf("\nBackup task starting with exhausted budget\n");

      kern_raise(XINVALID_TASK, p);

      lev->CP[p] = 0;

      /* we kill the current activation */

      level_table[ lev->scheduling_level ]->

        guest_end(lev->scheduling_level, p);

      return;

    }

  }

    /* the task returns into the ready queue by

       calling the guest_epilogue... */

    level_table[ lev->scheduling_level ]->

      guest_epilogue(lev->scheduling_level,p);

}

static void CBS_FT_task_activate(LEVEL l, PID p)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  ll_gettime(TIME_EXACT, &proc_table[p].request_time);

  if (lev->P_or_B[p] == BACKUP) {

    kern_printf("\nTrying to activate a BACKUP task!\n");

    kern_raise(XINVALID_TASK, p);

  }

  else {

    /* If idle=1, then we have to discharge the capacities stored in

       the capacity queue up to the length of the idle interval */

    if (lev->idle == 1) {

      TIME interval;

      struct timespec delta;

      lev->idle = 0;

      SUBTIMESPEC(&proc_table[p].request_time, &lev->start_idle, &delta);

      /* length of the idle interval expressed in usec! */

      interval = TIMESPEC2NANOSEC(&delta) / 1000;

      /* it discharge the available capacities from the capacity queue */

      while (interval > 0 && lev->queue != NULL) {

        struct timespec dead;

        int             cap;

        c_readfirst(&dead, &cap, lev->queue);

        if (cap > interval) {

          c_writefirst(dead, cap - interval, lev->queue);

          interval = 0;

        }

        else {

          interval -= cap;

          c_extractfirst(&lev->queue);

        }      

      }

    }

    CBS_FT_activation(lev, p, &proc_table[p].request_time);

    /* Set the reactivation timer */

    TIMESPEC_ASSIGN(&lev->reactivation_time[p], &lev->cbs_ft_dline[p]);

    lev->reactivation_timer[p] = kern_event_post(&lev->reactivation_time[p],

                                                 CBS_FT_timer_reactivate,

                                                 (void *)p);

    //  kern_printf("act : %d %d |",lev->cbs_ft_dline[p].tv_nsec/1000,p);

  }

}

static void CBS_FT_task_insert(LEVEL l, PID p)

{

  printk("CBS_FT_task_insert\n");

  kern_raise(XINVALID_TASK,p);

}

static void CBS_FT_task_extract(LEVEL l, PID p)

{

  printk("CBS_FT_task_extract\n");

  kern_raise(XINVALID_TASK,p);

}

static void CBS_FT_task_endcycle(LEVEL l, PID p)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  level_table[ lev->scheduling_level ]->

    guest_end(lev->scheduling_level,p);

  proc_table[p].status = CBS_FT_IDLE;

  if (lev->P_or_B[p] == PRIMARY) {

    if (lev->CP[p]) {

      JOB_TASK_MODEL job;

      /* We have to start the backup task  */

      TIMESPEC_ASSIGN(&lev->cbs_ft_dline[ lev->backup[p] ],

                      &lev->cbs_ft_dline[p]);

      proc_table[ lev->backup[p] ].avail_time = proc_table[p].avail_time;

      lev->CP[p] = 0;

      /* and, finally, we insert the backup task in the master level */

      job_task_default_model(job, lev->cbs_ft_dline[p]);

      job_task_def_yesexc(job);

      level_table[ lev->scheduling_level ]->

        guest_create(lev->scheduling_level, lev->backup[p],

                     (TASK_MODEL *)&job);

      level_table[ lev->scheduling_level ]->

        guest_activate(lev->scheduling_level, lev->backup[p]);

    }

    else {

      /* A spare capacity is inserted in the capacity queue!! */

      proc_table[p].avail_time += proc_table[ lev->backup[p] ].wcet;    

      if (proc_table[p].avail_time > 0) {

        c_insert(lev->cbs_ft_dline[p], proc_table[p].avail_time,

                 &lev->queue, p);

        proc_table[p].avail_time = 0;

      }

    }

  }

  else {

    /* this branch is for backup tasks:

       A spare capacity is inserted in the capacity queue!! */

    if (proc_table[p].avail_time > 0) {

      c_insert(lev->cbs_ft_dline[p], proc_table[p].avail_time,

               &lev->queue, p);

      proc_table[p].avail_time = 0;

    }

  }  

}

static void CBS_FT_task_end(LEVEL l, PID p)

{

  CBS_FT_level_des *lev = (CBS_FT_level_des *)(level_table[l]);

  /* A backup task cannot be killed, this behaviour can be modified

     in a new release */

  if (lev->P_or_B[p] == BACKUP) {

    kern_printf("\nKilling a BACKUP task!\n");

    kern_raise(XINVALID_TASK, p);

    return;

  }

  /* check if the capacity becomes negative... */

  /* there is a while because if the wcet is << than the system tick

     we need to postpone the deadline many times */

  while (proc_table[p].avail_time < 0) {

    /* the CBS_FT rule for recharging the capacity */

    proc_table[p].avail_time += lev->maxcap[p];