Subversion Repositories shark

/*

 * 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: ss.c,v 1.4 2003-01-07 17:07:51 pj Exp $

 File:        $File$

 Revision:    $Revision: 1.4 $

 Last update: $Date: 2003-01-07 17:07:51 $

 ------------

 This file contains the aperiodic Sporadic Server (SS).

 Note: in the following, server capacity and server budget are used as

       synonyms.

 When scheduling in background  the flags field has the SS_BACKGROUND bit set

 When scheduling a task because it is pointed by another task via shadows,

 the task have to be extracted from the wait queue or the master level. To

 check this we have to look at the activated field; it is != NIL if a task

 is inserted into the master level. Only a task at a time can be inserted

 into the master level.

 The capacity of the server must be updated

 - when scheduling a task normally

 - when scheduling a task because it is pointed by a shadow

   but not when scheduling in background.

 When a task is extracted from the system no scheduling has to be done

 until the task reenter into the system. To implement this, when a task

 is extracted we block the background scheduling (the scheduling with the

 master level is already blocked because the activated field is not

 reset to NIL) using the SS_BACKGROUNDBLOCK bit.

 nact[p] is -1 if the task set the activations to SKIP, >= 0 otherwise

 In contrast to classic SS scheme, the activation happens when

 a task does a create request while there is positive budget (instead to

 becomes active when there is a running task with priority higger then or

 equal to the server).

 So the replenish time is estabished on task arrival time. Replenish time

 is calculated as usual: activation time + server period.

 When the server ends its budget, becomes not active until a replenishment

 occurs.

 When a task ends its computation and there are no tasks to schedule or,

 again, the server budget ends, a replenish amount is posted so that, when

 replenish time fires, the server budget will be updated. Replenish

 amount is determined depending on how much time tasks have ran.

 Replenish amount does't takes into account periods during witch tasks

 handled by SS are preempted.

 There are two models used to handle a task is running into a critic section

 (owning a mutex): "nostop" model and "stop" model.

 Using the "nostop" model, a task that runs into a critic section is not

 stopped when server ends its budget. This is done so higger priority tasks

 waiting for mutex are not blocked for so much time to replenish time occurs.

 When this happens the server capacity becomes negative and the replenish

 amount takes into account the negative budget part.

 With "stop" model running task is always suspended when server budget ends.

 If suspended task owns a mutex shared with higger priority task, the last

 one cannot runs until the mutex will be released. Higger priority task

 must waits at least upto next replenish time, when server budget will be

 refulled and suspended task runs again.

 Using "nostop" model, SS can uses more bandwidth respect to assigned

 capacity (due to negative budgets). So, calculating the guarantee, the

 longer critic section of all tasks handled by SS must be considered.

 SS can be used either with EDF or RM master level.

 Read SS.h for further details.

**/

/*

 * 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

 *

 */

#include <stdlib.h>

#include <modules/ss.h>

#include <ll/stdio.h>

#include <ll/string.h>

#include <ll/sys/ll/event.h>

#include <kernel/const.h>

#include <kernel/model.h>

#include <kernel/model.h>

#include <kernel/descr.h>

#include <kernel/var.h>

#include <kernel/func.h>

#include <kernel/trace.h>

/* For debugging purpose */

//#define DEBUG 1

/*+ Status used in the level +*/

#define SS_WAIT          APER_STATUS_BASE    /*+ waiting the service   +*/

/*+ Some useful macros +*/

#define BACKGROUND_ON  (lev->flags & SS_BACKGROUND)

extern struct event *firstevent;

/*+ the level redefinition for the Sporadic Server +*/

typedef struct {

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

  /* The wcet are stored in the task descriptor's priority

     field, so no other fields are needed                      */

  int nact[MAX_PROC]; /*+ number of pending activations       +*/

  struct timespec lastdline; /*+ the last deeadline assigned to

                                 a SS task                    +*/

  int Cs;          /*+ server capacity                        +*/

  int availCs;     /*+ server avail time                      +*/

  int period;      /*+ Server period +*/

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

  IQUEUE wait;     /*+ the wait queue of the SS               +*/

  PID activated;   /*+ the task inserted in another queue     +*/

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

  LEVEL scheduling_level;

  int replenishment[SS_MAX_REPLENISH]; /*+ contains replenish amounts +*/

  int rfirst,rlast;                    /*+ first and last valid replenish

                                            in replenish queue +*/

  int rcount;                           /*+ queued replenishments +*/

  int replenish_amount;            /*+ partial replenishments before post +*/

  ss_status server_active;         /*+ Is server active? +*/

} SS_level_des;

/*+ function prototypes +*/

void SS_internal_status(LEVEL l);

static void SS_replenish_timer(void *arg);

/*-------------------------------------------------------------------*/

/*** Utility functions ***/

/* These are for dinamic queue. **Disabled** */

#if 0

/* These routines are not tested, be carefull */

/*+ SS local memory allocator.

    Can be used for performance optimization.

    The interface is the same of kern_alloc() +*/

void inline * ss_alloc(DWORD b) {

        /* Now simply wraps to standard kernel alloc */

        return kern_alloc(b);

}

void ssq_inslast(LEVEL l, replenishq *elem) {

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

        if(lev->rqueue_last == NULL) { /* empty queue */

                lev->rqueue_last=elem;

                lev->rqueue_first=elem;

                return;

        }

        elem->next = NULL;

        lev->rqueue_last->next = elem;

        lev->rqueue_last = elem;

}

replenishq *ssq_getfirst(LEVEL l) {

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

        replenishq *tmp;

        if(lev->rqueue_first == NULL) { /* empty queue */

                return 0;

        }

        tmp = lev->rqueue_first;

        lev->rqueue_first = tmp->next;

        if(lev->rqueue_first == NULL) { /* no more elements */

                lev->rqueue_last = NULL;

        }

        tmp->next = NULL;       /* to remove dangling pointer */

        return tmp;

}

#endif

/* For queue implemented with array.

   SS_MAX_REPLENISH array size assumed */

/*+ Insert an element at tail of replenish queue

        LEVEL l                 module level

        int   amount            element to insert

        RETURNS:

          NIL   no more space for insertion +*/

static inline int ssq_inslast (LEVEL l, int amount) {

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

  #ifdef DEBUG

  kern_printf("insl ");

  #endif

  if (lev->rcount == SS_MAX_REPLENISH) {

    return NIL; /* no more space in the queue */

  }

  lev->replenishment[lev->rlast++] = amount;

  lev->rlast %= SS_MAX_REPLENISH;

  lev->rcount++;

  #ifdef DEBUG

  printf_xy(0,0,WHITE,"%d",lev->rcount);

  #endif

  return 0;

}

/*+ Get first element from replenish queue

        LEVEL l         module level

        RETURS:

          extracted element

          NIL on empty queue +*/

static inline int ssq_getfirst (LEVEL l) {

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

  int tmp;

  #ifdef DEBUG

  kern_printf("getf ");

  #endif

  if (lev->rcount == 0) {

    return NIL; /* empty queue */

  }

  tmp = lev->replenishment[lev->rfirst++];

  lev->rfirst %= SS_MAX_REPLENISH;

  lev->rcount--;

  #ifdef DEBUG

  printf_xy(0,0,WHITE,"%d",lev->rcount);

  #endif

  return tmp;

}

/*+ Enquire for empty queue

        LEVEL l         module level

        RETURS:

          1     queue is empty +*/

static inline int ssq_isempty (LEVEL l) {

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

  return !(lev->rcount);

//  if(lev->rcount == 0)

//    return 1;

//  return 0;

}

/*+ Set replenish amount for budget used during task execution

        LEVEL l         module level */

static inline void SS_set_ra(LEVEL l)

{

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

  /* replenish must be set when the server is still active */

  if(lev->server_active == SS_SERVER_ACTIVE) {

    lev->server_active = SS_SERVER_NOTACTIVE;

    if(ssq_inslast(l, lev->replenish_amount) == NIL) {

      kern_printf("SS: no more space to post replenishment\n");

      kern_printf("You should recompile setting higher SS_MAX_REPLENISH into include/modules/ss.h\n");

      SS_internal_status(l);

      kern_raise(XINVALID_SS_REPLENISH,exec_shadow);

      #ifdef DEBUG

      sys_abort(-1);

      exit(-1);

      #endif

    }

    lev->replenish_amount = 0;

  }

  else {

    kern_printf("SS not active when posting R.A.\n");

    SS_internal_status(l);

    kern_raise(XINVALID_SS_REPLENISH,exec_shadow);

    #ifdef DEBUG

    sys_abort(-1);

    exit(-1);

    #endif

  }

}

/* ------------------------------------------------------------------ */

/* This static function activates the task pointed by lev->activated) */

static inline void SS_activation(SS_level_des *lev)

{

    /* those two defines are for readableness */

    PID   p;

    LEVEL m;

    JOB_TASK_MODEL j;          /* the guest model */

//    struct timespec ty;

    #ifdef DEBUG

    kern_printf("SS_acti ");

    #endif

    p = lev->activated;

    m = lev->scheduling_level;

#if 0

    /* if server is active, replenish time already set */

    if (lev->server_active == SS_SERVER_NOTACTIVE) {

       lev->server_active = SS_SERVER_ACTIVE;

       /* set replenish time */

       TIMESPEC_ASSIGN(&ty, &proc_table[p].request_time);

       ADDUSEC2TIMESPEC(lev->period, &ty);

       TIMESPEC_ASSIGN(&lev->lastdline, &ty);

       #ifdef DEBUG

       kern_printf("RT:%d.%d ",ty.tv_sec,ty.tv_nsec);

       #endif

       kern_event_post(&ty, SS_replenish_timer, (void *) l);

    }

#endif

    job_task_default_model(j,lev->lastdline);

    job_task_def_period(j,lev->period);

    level_table[m]->private_insert(m,p,(TASK_MODEL *)&j);

    #ifdef DEBUG

    kern_printf("PID:%p lastdl:%d.%d ",p,lev->lastdline.tv_sec,lev->lastdline.tv_nsec);

    #endif

}

/*+

    Before call capacity_timer, update server capacity

    and replenish amount.

+*/

static void SS_capacity_timer(void *arg) {

        LEVEL l = (LEVEL)arg;

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

        struct timespec ty;

        int tx;

        #ifdef DEBUG

        kern_printf("SS_captim ");

        #endif

        /* set replenish amount */

        /* task was running while budget ends */

        lev->server_active = SS_SERVER_NOTACTIVE;

        SUBTIMESPEC(&schedule_time, &cap_lasttime, &ty);

        tx = TIMESPEC2USEC(&ty);

        lev->availCs -= tx;

        if(ssq_inslast(l, tx+lev->replenish_amount) == NIL) {

           kern_printf("SS: no more space to post replenishment\n");

           kern_printf("    You should recompile setting higher SS_MAX_REPLENISH into include/modules/ss.h\n");

           SS_internal_status(l);

           kern_raise(XINVALID_SS_REPLENISH,exec_shadow);

           #ifdef DEBUG

           sys_abort(-1);

           exit(-1);

           #endif

        }

        lev->replenish_amount = 0;

        capacity_timer(NULL);

}

static void SS_replenish_timer(void *arg)

{

  LEVEL l = (LEVEL)arg;

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

  struct timespec ty;

  int amount;

    #ifdef DEBUG

    kern_printf("SS_reptim ");

    #endif

  /* availCs may be <0 because a task executed via a shadow for many time

     lev->activated == NIL only if the prec task was finished and there

     was not any other task to be put in the ready queue

     ... we are now activating the next task */

  if ((amount = ssq_getfirst(l)) != NIL) {

    lev->availCs += amount;

    #ifdef DEBUG

    kern_printf("AvaCs=%d ",lev->availCs);

    #endif

    if (lev->availCs > lev->Cs) {

      /* This should not be possible. I do so for robustness. */

      lev->availCs = lev->Cs;

      #ifdef DEBUG

      kern_printf("SS warning: budget higher then server capacity. Set to Cs.");

      #endif

    }

    if (lev->availCs <= 0) {

      /* we can be here if nostop model is used */

      #ifdef DEBUG

      kern_printf("WARNING: SS has non positive capacity after replenish.");

      #endif

      /* if there isn't pending replenishment and server

         is not active we must refull somehow.

         Otherwise SS remains not active forever */

      if(ssq_isempty(l) && lev->server_active == SS_SERVER_NOTACTIVE) {

        lev->availCs = lev->Cs;

        kern_printf("SS was full replenished due to irreversible non positive budget!!!\n");

        kern_printf("You should review your time extimation for critical sections ;)\n");

      }

    }

  }

  else {

    /* replenish queue is empty */

    kern_printf("Replenish Timer fires but no Replenish Amount defined\n");

    SS_internal_status(l);

    kern_raise(XINVALID_SS_REPLENISH,exec_shadow);

    #ifdef DEBUG

    sys_abort(-1);

    exit(-1);

    #endif

  }

  if (lev->availCs > 0 && lev->activated == NIL) {

    if (iq_query_first(&lev->wait) != NIL) {

      lev->activated = iq_getfirst(&lev->wait);

      /* if server is active, replenish time already set */

      if (lev->server_active == SS_SERVER_NOTACTIVE) {

         lev->server_active = SS_SERVER_ACTIVE;

         /* set replenish time */

         kern_gettime(&ty);

         ADDUSEC2TIMESPEC(lev->period, &ty);

         TIMESPEC_ASSIGN(&lev->lastdline, &ty);

         #ifdef DEBUG

         kern_printf("RT:%d.%d ",ty.tv_sec,ty.tv_nsec);

         #endif

         kern_event_post(&ty, SS_replenish_timer, (void *) l);

      }

      SS_activation(lev);

      event_need_reschedule();

    }

  }

}

static char *SS_status_to_a(WORD status)

{

  if (status < MODULE_STATUS_BASE)

    return "Unavailable"; //status_to_a(status);

  switch (status) {

    case SS_WAIT         : return "SS_Wait";

    default              : return "SS_Unknown";

  }

}

/*-------------------------------------------------------------------*/

/*** Level functions ***/

void SS_internal_status(LEVEL l)

{

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

  PID p = iq_query_first(&lev->wait);

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

    (lev->flags & SS_ENABLE_GUARANTEE_EDF ||

     lev->flags & SS_ENABLE_GUARANTEE_RM  )?"On":"Off");

  kern_printf("Used Bandwidth    : %u/%u\n",lev->U,MAX_BANDWIDTH);

  kern_printf("Period            : %d\n",lev->period);

  kern_printf("Capacity          : %d\n",lev->Cs);

  kern_printf("Avail capacity    : %d\n",lev->availCs);

  kern_printf("Server is %sactive\n",

     (lev->server_active == SS_SERVER_NOTACTIVE ? "not ":""));

  kern_printf("Pending RAs       : %d\n",lev->rcount);

  if (lev->activated != NIL)

    kern_printf("Activated: Pid: %d Name: %10s Dl: %ld.%ld Nact: %d Stat: %s\n",

                lev->activated,

                proc_table[lev->activated].name,

                iq_query_timespec(lev->activated,&lev->wait)->tv_sec,

                iq_query_timespec(lev->activated,&lev->wait)->tv_nsec,

                lev->nact[lev->activated],

                SS_status_to_a(proc_table[lev->activated].status));

  while (p != NIL) {

    kern_printf("Pid: %d\tName: %10s\tStatus: %s\n",

                p,

                proc_table[p].name,

                SS_status_to_a(proc_table[p].status));

    p = iq_query_next(p, &lev->wait);

  }

}

static PID SS_public_schedulerbackground(LEVEL l)

{

  /* the SS catch the background time to exec aperiodic activities */

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

  #ifdef DEBUG

  kern_printf("SS_levschbg ");

  #endif

  lev->flags |= SS_BACKGROUND;

  if (lev->flags & SS_BACKGROUND_BLOCK)

    return NIL;

  else

    return iq_query_first(&lev->wait);

}

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

static int SS_public_guaranteeEDF(LEVEL l, bandwidth_t *freebandwidth)

{

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

  #ifdef DEBUG

  kern_printf("SS_levguarEDF ");

  #endif

  if (*freebandwidth >= lev->U) {

    *freebandwidth -= lev->U;

    return 1;

  }

  else

    return 0;

}

static int SS_public_guaranteeRM(LEVEL l, bandwidth_t *freebandwidth)

{

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

  #ifdef DEBUG

  kern_printf("SS_levguarRM ");

  #endif

  if (*freebandwidth > lev->U + RM_MINFREEBANDWIDTH) {

    *freebandwidth -= lev->U;

    return 1;

  }

  else

    return 0;

}

/*-------------------------------------------------------------------*/

/***  Task functions  ***/

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

{

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

  SOFT_TASK_MODEL *s;

  #ifdef DEBUG

  kern_printf("SS_taskcre ");

  #endif

  if (m->pclass != SOFT_PCLASS) return -1;

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

  s = (SOFT_TASK_MODEL *)m;

  if (s->periodicity != APERIODIC) return -1;

  s = (SOFT_TASK_MODEL *)m;

  if (s->arrivals == SAVE_ARRIVALS)

    lev->nact[p] = 0;

  else

    lev->nact[p] = -1;

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

}

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

{

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

  struct timespec ty;

  #ifdef DEBUG

  kern_printf("SS_tdi ");

  #endif

  TIMESPEC_ASSIGN(&ty, &schedule_time);

  /* set replenish time */

  if(!BACKGROUND_ON) {

     if(lev->server_active == SS_SERVER_NOTACTIVE) {

        lev->server_active = SS_SERVER_ACTIVE;

        ADDUSEC2TIMESPEC(lev->period,&ty);

        TIMESPEC_ASSIGN(&lev->lastdline, &ty);

        #ifdef DEBUG

        kern_printf("tdiPID:%d RT:%d.%d ",p,ty.tv_sec,ty.tv_nsec);

        #endif

        kern_event_post(&ty, SS_replenish_timer,(void *) l);

     }

  }

  #ifdef DEBUG

  if (nostop) kern_printf("NOSTOP!!! ");

  #endif

  /* there is at least one task ready inserted in an RM or similar level.

     Note that we can't check the status because the scheduler sets it

     to exe before calling task_dispatch.

     We have to check lev->activated != p instead */

  if (lev->activated != p) {

    iq_extract(p, &lev->wait);

    #ifdef DEBUG

    kern_printf("extr task:%d ",p);

    #endif

  }

  else {

    #ifdef DEBUG

    if (nostop) kern_printf("(gd status=%d)",proc_table[p].status);

    #endif

    level_table[lev->scheduling_level]->

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

  }

  /* set capacity timer */

  if (!nostop && !BACKGROUND_ON) {

    TIMESPEC_ASSIGN(&ty, &schedule_time);

//    kern_printf("ty:%d.%d ",ty.tv_sec,ty.tv_nsec);

    ADDUSEC2TIMESPEC((lev->availCs<=0 ? 0:lev->availCs),&ty);

//    kern_printf("avCs:%d ty:%d.%d ",lev->availCs,ty.tv_sec,ty.tv_nsec);

    /* stop the task if budget ends */

    #ifdef DEBUG

    kern_printf("PID:%d ST=%d.%d  ",p,ty.tv_sec,ty.tv_nsec);

    #endif

    cap_timer = kern_event_post(&ty, SS_capacity_timer,(void *) l);

  }

}

static void SS_public_epilogue(LEVEL l, PID p) {

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

  struct timespec ty;

  int tx;

  #ifdef DEBUG

  kern_printf("SS_tep ");

  #endif

  /* update the server capacity */

  if (BACKGROUND_ON)

    lev->flags &= ~SS_BACKGROUND;

  else {

    SUBTIMESPEC(&schedule_time, &cap_lasttime, &ty);

//    kern_printf("ty:%d.%d ",ty.tv_sec,ty.tv_nsec);

    tx = TIMESPEC2USEC(&ty);

    lev->availCs -= tx;

//    kern_printf("avCs:%d ty:%d.%d ",lev->availCs,ty.tv_sec,ty.tv_nsec);

    lev->replenish_amount += tx;

    #ifdef DEBUG

    kern_printf("RA:%d ",lev->replenish_amount);

    #endif

  }

  /* check if the server capacity is finished... */

  if (lev->availCs <= 0) {

    /* The server slice has finished... do the task_end!!!

       A first version of the module used the task_endcycle, but it was

       not conceptually correct because the task didn't stop because it

       finished all the work, but because the server didn't have budget!

       So, if the task_endcycle is called, the task remain into the

       master level, and we can't wake him up if, for example, another

       task point the shadow to it!!! */

    /* set replenish amount */

    if(!(BACKGROUND_ON)) {

      if(lev->server_active == SS_SERVER_ACTIVE) {

        lev->server_active = SS_SERVER_NOTACTIVE;

        if(ssq_inslast(l, lev->replenish_amount) == NIL) {

          kern_printf("SS: no more space to post replenishment\n");

          kern_printf("You should recompile setting higher SS_MAX_REPLENISH into include/modules/ss.h\n");

          SS_internal_status(l);

          kern_raise(XINVALID_SS_REPLENISH,exec_shadow);

          #ifdef DEBUG

          sys_abort(-1);

          exit(-1);

          #endif

        }

        lev->replenish_amount = 0;

      }

    }

    if (lev->activated == p)

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

    iq_insertfirst(p, &lev->wait);

    proc_table[p].status = SS_WAIT;

    lev->activated = NIL;

  }

  else {

    /* The task has been preempted.

       It returns into the ready queue or to the

       wait queue by calling the private_epilogue... */

    if (lev->activated == p) {  /* goes into ready queue */

      level_table[ lev->scheduling_level ]->

        private_epilogue(lev->scheduling_level,p);

    }

    else {                      /* goes into wait queue */

      iq_insertfirst(p, &lev->wait);

      proc_table[p].status = SS_WAIT;

    }

  }

}

static void SS_public_activate(LEVEL l, PID p)

{

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

        struct timespec ty;

        #ifdef DEBUG

        kern_printf("SS_tacti ");

        #endif

        if (lev->activated == p || proc_table[p].status == SS_WAIT) {

                if (lev->nact[p] != -1) lev->nact[p]++;

        }

        else if (proc_table[p].status == SLEEP) {

                if (lev->activated == NIL && lev->availCs > 0) {

                  if(!BACKGROUND_ON) {

                    /* if server is active, replenish time already set */

                    if (lev->server_active == SS_SERVER_NOTACTIVE) {

                      lev->server_active = SS_SERVER_ACTIVE;

                      /* set replenish time */

                      kern_gettime(&ty);

                      ADDUSEC2TIMESPEC(lev->period, &ty);

                      TIMESPEC_ASSIGN(&lev->lastdline, &ty);

                      #ifdef DEBUG

                      kern_printf("RT=%d.%d ",ty.tv_sec,ty.tv_nsec);

                      #endif

                      kern_event_post(&ty, SS_replenish_timer, (void *) l);

                    }

                  }

                  lev->activated = p;

                  SS_activation(lev);

                }

                else {

                        iq_insertlast(p, &lev->wait);

                        proc_table[p].status = SS_WAIT;

                }

        }

        else {

                kern_printf("SS_REJ%d %d %d %d ",

                            p,

                            proc_table[p].status,

                            lev->activated,

                            lev->wait.first);

                return;

        }

}

static void SS_public_unblock(LEVEL l, PID p)

{

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

  #ifdef DEBUG

  kern_printf("SS_tins ");

  #endif

  lev->flags &= ~SS_BACKGROUND_BLOCK;

  lev->activated = NIL;

  /* when we reinsert the task into the system, the server capacity

     is always 0 because nobody executes with the SS before... */

  iq_insertfirst(p, &lev->wait);

  proc_table[p].status = SS_WAIT;

}

static void SS_public_block(LEVEL l, PID p)

{

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

  #ifdef DEBUG

  kern_printf("SS_textr ");

  #endif