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/*
 * Project: S.Ha.R.K.
 *
 * Coordinators:
 *   Giorgio Buttazzo    <giorgio@sssup.it>
 *   Paolo Gai           <pj@gandalf.sssup.it>
 *
 * Authors     :
 *      Giacomo Guidi    <giacomo@gandalf.sssup.it>
 *      Mauro Marinoni
 *      Anton Cervin
 *
 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
 *
 * http://www.sssup.it
 * http://retis.sssup.it
 * http://shark.sssup.it
 */

/*
 * 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 <kernel/model.h>
#include <kernel/descr.h>
#include <kernel/var.h>
#include <kernel/func.h>

#include <stdlib.h>

#include <modules/elastic.h>

#include <tracer.h>

#define ELASTIC_EMPTY_SLOT    0
#define ELASTIC_PRESENT       1

#define ELASTIC_IDLE          APER_STATUS_BASE

//#define ELASTIC_DEBUG

typedef struct {

  /* Task parameters (set/changed by the user) */

  TIME Tmin;   /* The nominal (minimum) period */
  TIME Tmax;   /* The maximum tolerable period */
  TIME C;      /* The declared worst-case execution time */
  int  E;      /* The elasticity coefficient */
  int  beta;   /* PERIOD_SCALING or WCET_SCALING */

  /* Task variables (changed by the module) */

  struct timespec dline;  /* The current absolute deadline */
 
  ext_bandwidth_t Umax;       /* The maximum utilization, Umax = C/Tmin  */
  ext_bandwidth_t Umin;       /* The minimum utilization, Umin = C/Tmax  */

  ext_bandwidth_t U;          /* The current utilization       */
  TIME T;                 /* The current period, T = C/U   */

  int  flags;

} ELASTIC_task_descr;

typedef struct {
  level_des l;     /*+ the standard level descriptor          +*/

  ext_bandwidth_t U;   /*+ the bandwidth reserved for elastic tasks  +*/

  ELASTIC_task_descr elist[MAX_PROC];

  LEVEL scheduling_level;

  LEVEL current_level;

  int flags;

} ELASTIC_level_des;


/* Checks feasability and computes new utilizations for the task set */

static int ELASTIC_compress(ELASTIC_level_des *lev) {

  PID i;
  ELASTIC_task_descr *t;
  int ok;
 
  ext_bandwidth_t Umin;  // minimum utilization
  ext_bandwidth_t Umax;  // nominal (maximum) utilization of compressable tasks

  ext_bandwidth_t Uf;    // amount of non-compressable utilization
  int Ev;                // sum of elasticity among compressable tasks

  Umin = 0;
  Umax = 0;

  for (i=0; i<MAX_PROC; i++) {
    t = &lev->elist[i];
    if (t->flags & ELASTIC_PRESENT) {
      if (t->E == 0) {
        Umin += t->U;
        Umax += t->U;
      } else {
        Umin += t->Umin;
        Umax += t->Umax;
        t->U = t->Umax;   // reset previous saturations
        t->T = ((long long)t->C * (long long)MAX_BANDWIDTH) / t->U;
      }
    }
  }
 
  if (Umin > lev->U) return -1;  // NOT FEASIBLE

  if (Umax <= lev->U) return 0;  // FEASIBLE WITH MAXIMUM UTILIZATIONS

  do {
    Uf = 0;
    Ev = 0;
    Umax = 0;

    for (i=0; i<MAX_PROC; i++) {
      t = &lev->elist[i];
      if (t->flags & ELASTIC_PRESENT) {
        if (t->E == 0 || t->U == t->Umin) {
          Uf += t->U;
        } else {
          Ev += t->E;
          Umax += t->Umax;
        }
      }
    }
   
    ok = 1;
   
    for (i=0; i<MAX_PROC; i++) {
      t = &lev->elist[i];
      if (t->flags & ELASTIC_PRESENT) {
        if (t->E > 0 && t->U > t->Umin) {
          t->U = t->Umax - (Umax - lev->U + Uf) * t->E / Ev;
          if (t->U < t->Umin) {
            t->U = t->Umin;
            ok = 0;
          }
          t->T = ((long long)t->C * (long long)MAX_BANDWIDTH) / t->U;
        }
      }
    }

  } while (ok == 0);

  cprintf("New periods: ");
  for (i=0; i<MAX_PROC; i++) {
    t = &lev->elist[i];
    if (t->flags & ELASTIC_PRESENT) {
      cprintf("%s:%d ", proc_table[i].name, t->T);
    }
  }
  cprintf("\n");

  return 0; // FEASIBLE

}


static void ELASTIC_activation(ELASTIC_level_des *lev,
                               PID p,
                               struct timespec *acttime)
{
  JOB_TASK_MODEL job;

  /* Job deadline */
  TIMESPEC_ASSIGN(&(lev->elist[p].dline),acttime);
  ADDUSEC2TIMESPEC(lev->elist[p].T,&(lev->elist[p].dline));

  proc_table[p].avail_time = lev->elist[p].C;
  proc_table[p].wcet = lev->elist[p].C;

  /* Job insertion */
  job_task_default_model(job, lev->elist[p].dline);
  level_table[ lev->scheduling_level ]->
    private_insert(lev->scheduling_level, p, (TASK_MODEL *)&job);

}

static void ELASTIC_timer_act(void *arg) {

  PID p = (PID)(arg);
  ELASTIC_level_des *lev;
  struct timespec acttime;
                     
  #ifdef ELASTIC_DEBUG
    printk("(ELASTIC:Timer:%d)",p);
  #endif

  kern_gettime(&acttime);

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

  ELASTIC_activation(lev, p, &acttime);

  event_need_reschedule();

  /* Next activation */
  kern_event_post(&(lev->elist[p].dline), ELASTIC_timer_act, (void *)(p));
 
}

/* The on-line guarantee is enabled only if the appropriate flag is set... */
static int ELASTIC_public_guarantee(LEVEL l, bandwidth_t *freebandwidth)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  return 1;

  if (*freebandwidth >= lev->U) {
    *freebandwidth -= (unsigned int)lev->U;
    return 1;
  } else {
    return 0;
  }
}


static int ELASTIC_public_create(LEVEL l, PID p, TASK_MODEL *m)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);
  ELASTIC_TASK_MODEL *elastic = (ELASTIC_TASK_MODEL *)m;

  if (m->pclass != ELASTIC_PCLASS) return -1;
  if (m->level != 0 && m->level != l) return -1;

  if (elastic->C == 0) return -1;
  if (elastic->Tmin > elastic->Tmax) return -1;
  if (elastic->Tmax == 0) return -1;

  lev->elist[p].flags |= ELASTIC_PRESENT;

  NULL_TIMESPEC(&(lev->elist[p].dline));
  lev->elist[p].Tmin = elastic->Tmin;
  lev->elist[p].Tmax = elastic->Tmax;
  lev->elist[p].C = elastic->C;
  lev->elist[p].E = elastic->E;
  lev->elist[p].beta = elastic->beta;

  lev->elist[p].Umax = ((long long)MAX_BANDWIDTH * (long long)elastic->C)
                        / elastic->Tmin;
  lev->elist[p].Umin = ((long long)MAX_BANDWIDTH * (long long)elastic->C)
                        / elastic->Tmax;

  lev->elist[p].U = lev->elist[p].Umax;
  lev->elist[p].T = lev->elist[p].Tmin;

  if (ELASTIC_compress(lev) == -1) {
    lev->elist[p].flags = ELASTIC_EMPTY_SLOT;
    return -1;
  }

  proc_table[p].avail_time = elastic->C;
  proc_table[p].wcet       = elastic->C;
  proc_table[p].control    |= CONTROL_CAP;

  return 0;
}


static void ELASTIC_public_detach(LEVEL l, PID p)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

}

static int ELASTIC_public_eligible(LEVEL l, PID p)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  return 0;

}

static void ELASTIC_public_dispatch(LEVEL l, PID p, int nostop)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  #ifdef ELASTIC_DEBUG
    printk("(ELASTIC:Dsp:%d)",p);
  #endif

  level_table[ lev->scheduling_level ]->
    private_dispatch(lev->scheduling_level,p,nostop);

}

static void ELASTIC_public_epilogue(LEVEL l, PID p)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  #ifdef ELASTIC_DEBUG
    printk("(ELASTIC:Epi:%d)",p);
  #endif

  /* check if the wcet is finished... */
  if (proc_table[p].avail_time <= 0) {
   
    TRACER_LOGEVENT(FTrace_EVT_task_wcet_violation,(unsigned short int)proc_table[p].context,0);
    kern_raise(XWCET_VIOLATION,p);
   
  }

  level_table[ lev->scheduling_level ]->
      private_epilogue(lev->scheduling_level,p);

}

static void ELASTIC_public_activate(LEVEL l, PID p, struct timespec *t)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  #ifdef ELASTIC_DEBUG
    printk("(ELASTIC:Act:%d)", p);
  #endif
                                                                                                                             
  /* check if we are not in the SLEEP state */
  if (proc_table[p].status != SLEEP) {
                                                                                                                             
    return;
                                                                                                                             
  }

  ELASTIC_activation(lev,p,t);

  /* Next activation */
  kern_event_post(&(lev->elist[p].dline), ELASTIC_timer_act, (void *)(p));

}

static void ELASTIC_public_unblock(LEVEL l, PID p)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);
  struct timespec acttime;

  kern_gettime(&acttime);

  ELASTIC_activation(lev,p,&acttime);

}

static void ELASTIC_public_block(LEVEL l, PID p)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  level_table[ lev->scheduling_level ]->
    private_extract(lev->scheduling_level,p);

}

static int ELASTIC_public_message(LEVEL l, PID p, void *m)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);
  struct timespec acttime;

  switch((long)(m)) {

    case (long)(NULL):

      #ifdef ELASTIC_DEBUG
        printk("(ELASTIC:EndCyc:%d)",p);
      #endif

      level_table[ lev->scheduling_level ]->
        private_extract(lev->scheduling_level,p);

      proc_table[p].status = ELASTIC_IDLE;

      jet_update_endcycle(); /* Update the Jet data... */
      TRACER_LOGEVENT(FTrace_EVT_task_end_cycle,(unsigned short int)proc_table[p].context,(unsigned int)l);

      break;

    case 1:

      #ifdef ELASTIC_DEBUG
        printk("(ELASTIC:Disable:%d)",p);
      #endif

      level_table[ lev->scheduling_level ]->
        private_extract(lev->scheduling_level,p);

      proc_table[p].status = SLEEP;

      TRACER_LOGEVENT(FTrace_EVT_task_disable,(unsigned short int)proc_table[p].context,(unsigned int)l);

      break;

  }

  return 0;

}

static void ELASTIC_public_end(LEVEL l, PID p)
{
  ELASTIC_level_des *lev = (ELASTIC_level_des *)(level_table[l]);

  level_table[ lev->scheduling_level ]->
    private_extract(lev->scheduling_level,p);

}

/*+ Registration function +*/
LEVEL ELASTIC_register_level(int flags, LEVEL master, ext_bandwidth_t U)
{
  LEVEL l;            /* the level that we register */
  ELASTIC_level_des *lev;  /* for readableness only */
  PID i;

  printk("ELASTIC_register_level\n");

  /* request an entry in the level_table */
  l = level_alloc_descriptor(sizeof(ELASTIC_level_des));

  lev = (ELASTIC_level_des *)level_table[l];

  /* fill the standard descriptor */
  if (flags & ELASTIC_ENABLE_GUARANTEE)
    lev->l.public_guarantee = ELASTIC_public_guarantee;
  else
    lev->l.public_guarantee = NULL;
  lev->l.public_create    = ELASTIC_public_create;
  lev->l.public_detach    = ELASTIC_public_detach;
  lev->l.public_end       = ELASTIC_public_end;
  lev->l.public_eligible  = ELASTIC_public_eligible;
  lev->l.public_dispatch  = ELASTIC_public_dispatch;
  lev->l.public_epilogue  = ELASTIC_public_epilogue;
  lev->l.public_activate  = ELASTIC_public_activate;
  lev->l.public_unblock   = ELASTIC_public_unblock;
  lev->l.public_block     = ELASTIC_public_block;
  lev->l.public_message   = ELASTIC_public_message;

  /* fill the ELASTIC task descriptor part */
  for (i=0; i<MAX_PROC; i++) {
     NULL_TIMESPEC(&(lev->elist[i].dline));
     lev->elist[i].Tmin = 0;
     lev->elist[i].Tmax = 0;
     lev->elist[i].T = 0;
     lev->elist[i].U = 0;
     lev->elist[i].C = 0;
     lev->elist[i].E = 0;
     lev->elist[i].beta = 0;
     lev->elist[i].flags = ELASTIC_EMPTY_SLOT;
  }

  lev->U = U;

  lev->scheduling_level = master;

  lev->current_level = l;

  lev->flags = flags;

  return l;
}