src/surf/maxmin.c

   1 /* Copyright (c) 2004-2011. The SimGrid Team.
   2  * All rights reserved.                                                     */
   3
   4 /* This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the license (GNU LGPL) which comes with this package. */
   6
   7
   8 #include "xbt/sysdep.h"
   9 #include "xbt/log.h"
  10 #include "xbt/mallocator.h"
  11 #include "maxmin_private.h"
  12 #include <stdlib.h>
  13 #include <stdio.h>              /* sprintf */
  14 #include <math.h>
  15 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
  16                                 "Logging specific to SURF (maxmin)");
  17
  18 double sg_maxmin_precision = 0.00001;
  19
  20 static void *lmm_variable_mallocator_new_f(void);
  21 static void lmm_variable_mallocator_free_f(void *var);
  22 #define lmm_variable_mallocator_reset_f ((void_f_pvoid_t)NULL)
  23 static void lmm_update_modified_set(lmm_system_t sys,
  24                                     lmm_constraint_t cnst);
  25 static void lmm_remove_all_modified_set(lmm_system_t sys);
  26 static int Global_debug_id = 1;
  27 static int Global_const_debug_id = 1;
  28
  29 lmm_system_t lmm_system_new(int selective_update)
  30 {
  31   lmm_system_t l = NULL;
  32   s_lmm_variable_t var;
  33   s_lmm_constraint_t cnst;
  34
  35   l = xbt_new0(s_lmm_system_t, 1);
  36
  37   l->modified = 0;
  38   l->selective_update_active = selective_update;
  39   l->visited_counter = 1;
  40
  41   XBT_DEBUG("Setting selective_update_active flag to %d\n",
  42          l->selective_update_active);
  43
  44   xbt_swag_init(&(l->variable_set),
  45                 xbt_swag_offset(var, variable_set_hookup));
  46   xbt_swag_init(&(l->constraint_set),
  47                 xbt_swag_offset(cnst, constraint_set_hookup));
  48
  49   xbt_swag_init(&(l->active_constraint_set),
  50                 xbt_swag_offset(cnst, active_constraint_set_hookup));
  51
  52   xbt_swag_init(&(l->modified_constraint_set),
  53                 xbt_swag_offset(cnst, modified_constraint_set_hookup));
  54   xbt_swag_init(&(l->saturated_variable_set),
  55                 xbt_swag_offset(var, saturated_variable_set_hookup));
  56   xbt_swag_init(&(l->saturated_constraint_set),
  57                 xbt_swag_offset(cnst, saturated_constraint_set_hookup));
  58
  59   l->variable_mallocator = xbt_mallocator_new(65536,
  60                                               lmm_variable_mallocator_new_f,
  61                                               lmm_variable_mallocator_free_f,
  62                                               lmm_variable_mallocator_reset_f);
  63
  64   return l;
  65 }
  66
  67 void lmm_system_free(lmm_system_t sys)
  68 {
  69   lmm_variable_t var = NULL;
  70   lmm_constraint_t cnst = NULL;
  71
  72   while ((var = extract_variable(sys))) {
  73     XBT_WARN
  74         ("Variable %p (%d) still in LMM system when freing it: this may be a bug",
  75          var, var->id_int);
  76     lmm_var_free(sys, var);
  77   }
  78
  79   while ((cnst = extract_constraint(sys)))
  80     lmm_cnst_free(sys, cnst);
  81
  82   xbt_mallocator_free(sys->variable_mallocator);
  83   free(sys);
  84 }
  85
  86 XBT_INLINE void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  87 {
  88   int i;
  89   int n;
  90
  91   lmm_element_t elem = NULL;
  92
  93   XBT_IN("(sys=%p, var=%p)", sys, var);
  94   sys->modified = 1;
  95
  96   n = 0;
  97   for (i = 0; i < var->cnsts_number; i++) {
  98     elem = &var->cnsts[i];
  99     xbt_swag_remove(elem, &(elem->constraint->element_set));
 100     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
 101     if (!xbt_swag_size(&(elem->constraint->element_set)))
 102       make_constraint_inactive(sys, elem->constraint);
 103     else {
 104       if (n < i)
 105         var->cnsts[n].constraint = elem->constraint;
 106       n++;
 107     }
 108   }
 109   if (n) {
 110     var->cnsts_number = n;
 111     lmm_update_modified_set(sys, var->cnsts[0].constraint);
 112   }
 113
 114   var->cnsts_number = 0;
 115   XBT_OUT();
 116 }
 117
 118 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
 119 {
 120
 121   lmm_variable_disable(sys, var);
 122   xbt_mallocator_release(sys->variable_mallocator, var);
 123 }
 124
 125 static XBT_INLINE void lmm_cnst_free(lmm_system_t sys,
 126                                      lmm_constraint_t cnst)
 127 {
 128 /*   xbt_assert(xbt_swag_size(&(cnst->element_set)), */
 129 /*            "This list should be empty!"); */
 130   make_constraint_inactive(sys, cnst);
 131   free(cnst);
 132 }
 133
 134 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 135                                     double bound_value)
 136 {
 137   lmm_constraint_t cnst = NULL;
 138   s_lmm_element_t elem;
 139
 140   cnst = xbt_new0(s_lmm_constraint_t, 1);
 141   cnst->id = id;
 142   cnst->id_int = Global_const_debug_id++;
 143   xbt_swag_init(&(cnst->element_set),
 144                 xbt_swag_offset(elem, element_set_hookup));
 145   xbt_swag_init(&(cnst->active_element_set),
 146                 xbt_swag_offset(elem, active_element_set_hookup));
 147
 148   cnst->bound = bound_value;
 149   cnst->usage = 0;
 150   cnst->shared = 1;
 151   insert_constraint(sys, cnst);
 152
 153   return cnst;
 154 }
 155
 156 XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
 157 {
 158   cnst->shared = 0;
 159 }
 160
 161 XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
 162 {
 163   return (cnst->shared);
 164 }
 165
 166 XBT_INLINE void lmm_constraint_free(lmm_system_t sys,
 167                                     lmm_constraint_t cnst)
 168 {
 169   remove_constraint(sys, cnst);
 170   lmm_cnst_free(sys, cnst);
 171 }
 172
 173 static void *lmm_variable_mallocator_new_f(void)
 174 {
 175   lmm_variable_t var = xbt_new(s_lmm_variable_t, 1);
 176   var->cnsts = NULL; /* will be created by realloc */
 177   return var;
 178 }
 179
 180 static void lmm_variable_mallocator_free_f(void *var)
 181 {
 182   xbt_free(((lmm_variable_t) var)->cnsts);
 183   xbt_free(var);
 184 }
 185
 186 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 187                                 double weight,
 188                                 double bound, int number_of_constraints)
 189 {
 190   lmm_variable_t var = NULL;
 191   int i;
 192
 193   XBT_IN("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 194           sys, id, weight, bound, number_of_constraints);
 195
 196   var = xbt_mallocator_get(sys->variable_mallocator);
 197   var->id = id;
 198   var->id_int = Global_debug_id++;
 199   var->cnsts = xbt_realloc(var->cnsts, number_of_constraints * sizeof(s_lmm_element_t));
 200   for (i = 0; i < number_of_constraints; i++) {
 201     var->cnsts[i].element_set_hookup.next = NULL;
 202     var->cnsts[i].element_set_hookup.prev = NULL;
 203     var->cnsts[i].active_element_set_hookup.next = NULL;
 204     var->cnsts[i].active_element_set_hookup.prev = NULL;
 205     var->cnsts[i].constraint = NULL;
 206     var->cnsts[i].variable = NULL;
 207     var->cnsts[i].value = 0.0;
 208   }
 209   var->cnsts_size = number_of_constraints;
 210   var->cnsts_number = 0;
 211   var->weight = weight;
 212   var->bound = bound;
 213   var->value = 0.0;
 214   var->visited = sys->visited_counter - 1;
 215   var->mu = 0.0;
 216   var->new_mu = 0.0;
 217   var->func_f = func_f_def;
 218   var->func_fp = func_fp_def;
 219   var->func_fpi = func_fpi_def;
 220
 221   var->variable_set_hookup.next = NULL;
 222   var->variable_set_hookup.prev = NULL;
 223   var->saturated_variable_set_hookup.next = NULL;
 224   var->saturated_variable_set_hookup.prev = NULL;
 225
 226   if (weight)
 227     xbt_swag_insert_at_head(var, &(sys->variable_set));
 228   else
 229     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 230   XBT_OUT();
 231   return var;
 232 }
 233
 234 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 235 {
 236   remove_variable(sys, var);
 237   lmm_var_free(sys, var);
 238 }
 239
 240 XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 241 {
 242   return (var->value);
 243 }
 244
 245 XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
 246 {
 247   return (var->bound);
 248 }
 249
 250 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 251                 lmm_variable_t var, double value)
 252 {
 253   lmm_element_t elem = NULL;
 254
 255   sys->modified = 1;
 256
 257   xbt_assert(var->cnsts_number < var->cnsts_size, "Too much constraints");
 258
 259   elem = &(var->cnsts[var->cnsts_number++]);
 260
 261   elem->value = value;
 262   elem->constraint = cnst;
 263   elem->variable = var;
 264
 265   if (var->weight)
 266     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 267   else
 268     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 269
 270   make_constraint_active(sys, cnst);
 271   lmm_update_modified_set(sys, cnst);
 272   if (var->cnsts_number > 1)
 273     lmm_update_modified_set(sys, var->cnsts[0].constraint);
 274 }
 275
 276 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 277                     lmm_variable_t var, double value)
 278 {
 279   int i;
 280   sys->modified = 1;
 281
 282   for (i = 0; i < var->cnsts_number; i++)
 283     if (var->cnsts[i].constraint == cnst)
 284       break;
 285
 286   if (i < var->cnsts_number) {
 287     if (cnst->shared)
 288       var->cnsts[i].value += value;
 289     else
 290       var->cnsts[i].value = MAX(var->cnsts[i].value, value);
 291     lmm_update_modified_set(sys, cnst);
 292   } else
 293     lmm_expand(sys, cnst, var, value);
 294 }
 295
 296 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 297                         lmm_variable_t var, double value)
 298 {
 299   int i;
 300
 301   for (i = 0; i < var->cnsts_number; i++)
 302     if (var->cnsts[i].constraint == cnst)
 303       break;
 304
 305   if (i < var->cnsts_number) {
 306     var->cnsts[i].value = value;
 307     sys->modified = 1;
 308     lmm_update_modified_set(sys, cnst);
 309   } else
 310     DIE_IMPOSSIBLE;
 311 }
 312
 313 XBT_INLINE lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 314                                                   lmm_variable_t var,
 315                                                   int num)
 316 {
 317   if (num < var->cnsts_number)
 318     return (var->cnsts[num].constraint);
 319   else
 320     return NULL;
 321 }
 322
 323 XBT_INLINE double lmm_get_cnst_weight_from_var(lmm_system_t sys,
 324                                                          lmm_variable_t var,
 325                                                          int num)
 326 {
 327   if (num < var->cnsts_number)
 328     return (var->cnsts[num].value);
 329   else
 330     return 0.0;
 331 }
 332
 333 XBT_INLINE int lmm_get_number_of_cnst_from_var(lmm_system_t sys,
 334                                                lmm_variable_t var)
 335 {
 336   return (var->cnsts_number);
 337 }
 338
 339 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 340                                      lmm_constraint_t cnst,
 341                                      lmm_element_t * elem)
 342 {
 343   if (!(*elem))
 344     *elem = xbt_swag_getFirst(&(cnst->element_set));
 345   else
 346     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 347   if (*elem)
 348     return (*elem)->variable;
 349   else
 350     return NULL;
 351 }
 352
 353 XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 354 {
 355   return cnst->id;
 356 }
 357
 358 XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 359 {
 360   return var->id;
 361 }
 362
 363 static XBT_INLINE int saturated_constraint_set_update(lmm_system_t sys,
 364                                                        lmm_constraint_t
 365                                                        cnst,
 366                                                        double *min_usage)
 367 {
 368   lmm_constraint_t useless_cnst = NULL;
 369
 370   XBT_IN("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 371   if (cnst->usage <= 0) {
 372     XBT_OUT();
 373     return 1;
 374   }
 375   if (cnst->remaining <= 0) {
 376     XBT_OUT();
 377     return 1;
 378   }
 379   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 380     *min_usage = cnst->remaining / cnst->usage;
 381     XBT_LOG(xbt_log_priority_trace,
 382          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 383          cnst->remaining, cnst->usage);
 384     while ((useless_cnst =
 385             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 386       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 387
 388     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 389   } else if (*min_usage == cnst->remaining / cnst->usage) {
 390     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 391   }
 392   XBT_OUT();
 393   return 0;
 394 }
 395
 396 static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 397 {
 398   lmm_constraint_t cnst = NULL;
 399   xbt_swag_t cnst_list = NULL;
 400   lmm_element_t elem = NULL;
 401   xbt_swag_t elem_list = NULL;
 402
 403   cnst_list = &(sys->saturated_constraint_set);
 404   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 405     elem_list = &(cnst->active_element_set);
 406     xbt_swag_foreach(elem, elem_list) {
 407       if (elem->variable->weight <= 0)
 408         break;
 409       if ((elem->value > 0))
 410         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 411     }
 412     xbt_swag_remove(cnst, cnst_list);
 413   }
 414 }
 415
 416 void lmm_print(lmm_system_t sys)
 417 {
 418   lmm_constraint_t cnst = NULL;
 419   lmm_element_t elem = NULL;
 420   lmm_variable_t var = NULL;
 421   xbt_swag_t cnst_list = NULL;
 422   xbt_swag_t var_list = NULL;
 423   xbt_swag_t elem_list = NULL;
 424   char print_buf[1024];
 425   char *trace_buf = xbt_malloc0(sizeof(char));
 426   double sum = 0.0;
 427
 428   /* Printing Objective */
 429   var_list = &(sys->variable_set);
 430   sprintf(print_buf, "MAX-MIN ( ");
 431   trace_buf =
 432       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 433   strcat(trace_buf, print_buf);
 434   xbt_swag_foreach(var, var_list) {
 435     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 436     trace_buf =
 437         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 438     strcat(trace_buf, print_buf);
 439   }
 440   sprintf(print_buf, ")");
 441   trace_buf =
 442       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 443   strcat(trace_buf, print_buf);
 444   XBT_DEBUG("%20s", trace_buf);
 445   trace_buf[0] = '\000';
 446
 447   XBT_DEBUG("Constraints");
 448   /* Printing Constraints */
 449   cnst_list = &(sys->active_constraint_set);
 450   xbt_swag_foreach(cnst, cnst_list) {
 451     sum = 0.0;
 452     elem_list = &(cnst->element_set);
 453     sprintf(print_buf, "\t");
 454     trace_buf =
 455         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 456     strcat(trace_buf, print_buf);
 457     sprintf(print_buf, "%s(",(cnst->shared)?"":"max");
 458     trace_buf =
 459       xbt_realloc(trace_buf,
 460                   strlen(trace_buf) + strlen(print_buf) + 1);
 461     strcat(trace_buf, print_buf);
 462     xbt_swag_foreach(elem, elem_list) {
 463       sprintf(print_buf, "%f.'%d'(%f) %s ", elem->value,
 464               elem->variable->id_int, elem->variable->value,(cnst->shared)?"+":",");
 465       trace_buf =
 466           xbt_realloc(trace_buf,
 467                       strlen(trace_buf) + strlen(print_buf) + 1);
 468       strcat(trace_buf, print_buf);
 469       if(cnst->shared)
 470         sum += elem->value * elem->variable->value;
 471       else
 472         sum = MAX(sum,elem->value * elem->variable->value);
 473     }
 474     sprintf(print_buf, "0) <= %f ('%d')", cnst->bound, cnst->id_int);
 475     trace_buf =
 476         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 477     strcat(trace_buf, print_buf);
 478
 479     if (!cnst->shared) {
 480       sprintf(print_buf, " [MAX-Constraint]");
 481       trace_buf =
 482           xbt_realloc(trace_buf,
 483                       strlen(trace_buf) + strlen(print_buf) + 1);
 484       strcat(trace_buf, print_buf);
 485     }
 486     XBT_DEBUG("%s", trace_buf);
 487     trace_buf[0] = '\000';
 488     xbt_assert(!double_positive(sum - cnst->bound),
 489                 "Incorrect value (%f is not smaller than %f): %g",
 490                 sum, cnst->bound, sum - cnst->bound);
 491   }
 492
 493   XBT_DEBUG("Variables");
 494   /* Printing Result */
 495   xbt_swag_foreach(var, var_list) {
 496     if (var->bound > 0) {
 497       XBT_DEBUG("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 498              var->bound);
 499       xbt_assert(!double_positive(var->value - var->bound),
 500                   "Incorrect value (%f is not smaller than %f",
 501                   var->value, var->bound);
 502     } else {
 503       XBT_DEBUG("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 504     }
 505   }
 506
 507   free(trace_buf);
 508 }
 509
 510 void lmm_solve(lmm_system_t sys)
 511 {
 512   lmm_variable_t var = NULL;
 513   lmm_constraint_t cnst = NULL;
 514   lmm_constraint_t cnst_next = NULL;
 515   lmm_element_t elem = NULL;
 516   xbt_swag_t cnst_list = NULL;
 517   xbt_swag_t var_list = NULL;
 518   xbt_swag_t elem_list = NULL;
 519   double min_usage = -1;
 520   double min_bound = -1;
 521
 522   if (!(sys->modified))
 523     return;
 524
 525   XBT_IN("(sys=%p)", sys);
 526
 527   /*
 528    * Compute Usage and store the variables that reach the maximum.
 529    */
 530   cnst_list =
 531       sys->
 532       selective_update_active ? &(sys->modified_constraint_set) :
 533       &(sys->active_constraint_set);
 534
 535   XBT_DEBUG("Active constraints : %d", xbt_swag_size(cnst_list));
 536   /* Init: Only modified code portions */
 537   xbt_swag_foreach(cnst, cnst_list) {
 538     elem_list = &(cnst->element_set);
 539     //XBT_DEBUG("Variable set : %d", xbt_swag_size(elem_list));
 540     xbt_swag_foreach(elem, elem_list) {
 541       var = elem->variable;
 542       if (var->weight <= 0.0)
 543         break;
 544       var->value = 0.0;
 545     }
 546   }
 547
 548   xbt_swag_foreach_safe(cnst, cnst_next, cnst_list) {
 549     /* INIT */
 550     cnst->remaining = cnst->bound;
 551     if (cnst->remaining == 0)
 552       continue;
 553     cnst->usage = 0;
 554     elem_list = &(cnst->element_set);
 555     xbt_swag_foreach(elem, elem_list) {
 556       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 557       if (elem->variable->weight <= 0)
 558         break;
 559       if ((elem->value > 0)) {
 560         if (cnst->shared)
 561           cnst->usage += elem->value / elem->variable->weight;
 562         else if (cnst->usage < elem->value / elem->variable->weight)
 563           cnst->usage = elem->value / elem->variable->weight;
 564
 565         make_elem_active(elem);
 566         if (sys->keep_track)
 567           xbt_swag_insert(elem->variable->id, sys->keep_track);
 568       }
 569     }
 570     XBT_DEBUG("Constraint Usage '%d' : %f", cnst->id_int, cnst->usage);
 571     /* Saturated constraints update */
 572     if(cnst->usage>0) {
 573       xbt_swag_remove(cnst, cnst_list);
 574       xbt_swag_insert_at_head(cnst, cnst_list);
 575     }
 576     saturated_constraint_set_update(sys, cnst, &min_usage);
 577   }
 578   saturated_variable_set_update(sys);
 579
 580   /* Saturated variables update */
 581
 582   do {
 583     /* Fix the variables that have to be */
 584     var_list = &(sys->saturated_variable_set);
 585
 586     xbt_swag_foreach(var, var_list) {
 587       if (var->weight <= 0.0)
 588         DIE_IMPOSSIBLE;
 589       /* First check if some of these variables have reach their upper
 590          bound and update min_usage accordingly. */
 591       XBT_DEBUG
 592           ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 593            var->id_int, var->bound, var->weight, min_usage,
 594            var->bound * var->weight);
 595       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 596         if (min_bound < 0)
 597           min_bound = var->bound;
 598         else
 599           min_bound = MIN(min_bound, var->bound);
 600         XBT_DEBUG("Updated min_bound=%f", min_bound);
 601       }
 602     }
 603
 604
 605     while ((var = xbt_swag_getFirst(var_list))) {
 606       int i;
 607
 608       if (min_bound < 0) {
 609         var->value = min_usage / var->weight;
 610       } else {
 611         if (min_bound == var->bound)
 612           var->value = var->bound;
 613         else {
 614           xbt_swag_remove(var, var_list);
 615           continue;
 616         }
 617       }
 618       XBT_DEBUG("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 619              min_usage, var->id_int, var->weight, var->id_int, var->value);
 620
 621
 622       /* Update usage */
 623
 624       for (i = 0; i < var->cnsts_number; i++) {
 625         elem = &var->cnsts[i];
 626         cnst = elem->constraint;
 627         if (cnst->shared) {
 628           double_update(&(cnst->remaining), elem->value * var->value);
 629           double_update(&(cnst->usage), elem->value / var->weight);
 630           if(cnst->usage<=0 || cnst->remaining<=0) {
 631             xbt_swag_remove(cnst, cnst_list);
 632             xbt_swag_insert_at_tail(cnst, cnst_list);
 633           }
 634           make_elem_inactive(elem);
 635         } else {                /* FIXME one day: We recompute usage.... :( */
 636           cnst->usage = 0.0;
 637           make_elem_inactive(elem);
 638           elem_list = &(cnst->element_set);
 639           xbt_swag_foreach(elem, elem_list) {
 640             if (elem->variable->weight <= 0)
 641               break;
 642             if (elem->variable->value > 0)
 643               break;
 644             if ((elem->value > 0)) {
 645               cnst->usage =
 646                   MAX(cnst->usage, elem->value / elem->variable->weight);
 647               XBT_DEBUG("Constraint Usage %d : %f", cnst->id_int,
 648                      cnst->usage);
 649               make_elem_active(elem);
 650             }
 651           }
 652         }
 653       }
 654       xbt_swag_remove(var, var_list);
 655     }
 656
 657     /* Find out which variables reach the maximum */
 658     min_usage = -1;
 659     min_bound = -1;
 660
 661     xbt_swag_foreach(cnst, cnst_list) {
 662       if(saturated_constraint_set_update(sys, cnst, &min_usage)) break;
 663     }
 664     saturated_variable_set_update(sys);
 665
 666   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 667
 668   sys->modified = 0;
 669   if (sys->selective_update_active)
 670     lmm_remove_all_modified_set(sys);
 671
 672   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 673     lmm_print(sys);
 674   }
 675   XBT_OUT();
 676 }
 677
 678 /* Not a O(1) function */
 679
 680 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 681                 lmm_variable_t var, double value)
 682 {
 683   int i;
 684
 685   for (i = 0; i < var->cnsts_number; i++)
 686     if (var->cnsts[i].constraint == cnst) {
 687       var->cnsts[i].value = value;
 688       sys->modified = 1;
 689       lmm_update_modified_set(sys, cnst);
 690       return;
 691     }
 692 }
 693
 694 /** \brief Attribute the value bound to var->bound.
 695  *
 696  *  \param sys the lmm_system_t
 697  *  \param var the lmm_variable_t
 698  *  \param bound the new bound to associate with var
 699  *
 700  *  Makes var->bound equal to bound. Whenever this function is called
 701  *  a change is  signed in the system. To
 702  *  avoid false system changing detection it is a good idea to test
 703  *  (bound != 0) before calling it.
 704  *
 705  */
 706 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 707                                double bound)
 708 {
 709   sys->modified = 1;
 710   var->bound = bound;
 711
 712   if (var->cnsts_number)
 713     lmm_update_modified_set(sys, var->cnsts[0].constraint);
 714 }
 715
 716
 717 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 718                                 double weight)
 719 {
 720   int i;
 721   lmm_element_t elem;
 722
 723   if (weight == var->weight)
 724     return;
 725   XBT_IN("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 726   sys->modified = 1;
 727   var->weight = weight;
 728   xbt_swag_remove(var, &(sys->variable_set));
 729   if (weight)
 730     xbt_swag_insert_at_head(var, &(sys->variable_set));
 731   else
 732     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 733
 734   for (i = 0; i < var->cnsts_number; i++) {
 735     elem = &var->cnsts[i];
 736     xbt_swag_remove(elem, &(elem->constraint->element_set));
 737     if (weight)
 738       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 739     else
 740       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 741
 742     if (i == 0)
 743       lmm_update_modified_set(sys, elem->constraint);
 744   }
 745   if (!weight)
 746     var->value = 0.0;
 747
 748   XBT_OUT();
 749 }
 750
 751 XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 752 {
 753   return var->weight;
 754 }
 755
 756 XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys,
 757                                             lmm_constraint_t cnst,
 758                                             double bound)
 759 {
 760   sys->modified = 1;
 761   lmm_update_modified_set(sys, cnst);
 762   cnst->bound = bound;
 763 }
 764
 765 XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 766 {
 767   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 768 }
 769
 770 XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t
 771                                                             sys)
 772 {
 773   return xbt_swag_getFirst(&(sys->active_constraint_set));
 774 }
 775
 776 XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t
 777                                                            sys,
 778                                                            lmm_constraint_t
 779                                                            cnst)
 780 {
 781   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 782 }
 783
 784 #ifdef HAVE_LATENCY_BOUND_TRACKING
 785 XBT_INLINE int lmm_is_variable_limited_by_latency(lmm_variable_t var)
 786 {
 787   return (double_equals(var->bound, var->value));
 788 }
 789 #endif
 790
 791
 792 /** \brief Update the constraint set propagating recursively to
 793  *  other constraints so the system should not be entirely computed.
 794  *
 795  *  \param sys the lmm_system_t
 796  *  \param cnst the lmm_constraint_t affected by the change
 797  *
 798  *  A recursive algorithm to optimize the system recalculation selecting only
 799  *  constraints that have changed. Each constraint change is propagated
 800  *  to the list of constraints for each variable.
 801  */
 802 static void lmm_update_modified_set_rec(lmm_system_t sys,
 803                                         lmm_constraint_t cnst)
 804 {
 805   lmm_element_t elem;
 806
 807   xbt_swag_foreach(elem, &cnst->element_set) {
 808     lmm_variable_t var = elem->variable;
 809     s_lmm_element_t *cnsts = var->cnsts;
 810     int i;
 811     for (i = 0; var->visited != sys->visited_counter
 812              && i < var->cnsts_number ; i++) {
 813       if (cnsts[i].constraint != cnst
 814           && !xbt_swag_belongs(cnsts[i].constraint,
 815                                &sys->modified_constraint_set)) {
 816         xbt_swag_insert(cnsts[i].constraint, &sys->modified_constraint_set);
 817         lmm_update_modified_set_rec(sys, cnsts[i].constraint);
 818       }
 819     }
 820     var->visited = sys->visited_counter;
 821   }
 822 }
 823
 824 static void lmm_update_modified_set(lmm_system_t sys,
 825                                     lmm_constraint_t cnst)
 826 {
 827   /* nothing to do if selective update isn't active */
 828   if (sys->selective_update_active
 829       && !xbt_swag_belongs(cnst, &sys->modified_constraint_set)) {
 830     xbt_swag_insert(cnst, &sys->modified_constraint_set);
 831     lmm_update_modified_set_rec(sys, cnst);
 832   }
 833 }
 834
 835 /** \brief Remove all constraints of the modified_constraint_set.
 836  *
 837  *  \param sys the lmm_system_t
 838  */
 839 static void lmm_remove_all_modified_set(lmm_system_t sys)
 840 {
 841   if (++sys->visited_counter == 1) {
 842     /* the counter wrapped around, reset each variable->visited */
 843     lmm_variable_t var;
 844     xbt_swag_foreach(var, &sys->variable_set)
 845       var->visited = 0;
 846   }
 847   xbt_swag_reset(&sys->modified_constraint_set);
 848 }