src/surf/maxmin.c

   1 /* Copyright (c) 2004, 2005, 2006, 2007, 2008, 2009, 2010. 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 static void lmm_variable_mallocator_reset_f(void *var);
  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 int sg_maxmin_selective_update = 1;
  27 static int Global_debug_id = 1;
  28 static int Global_const_debug_id = 1;
  29 extern xbt_swag_t keep_track;
  30
  31 lmm_system_t lmm_system_new(void)
  32 {
  33   lmm_system_t l = NULL;
  34   s_lmm_variable_t var;
  35   s_lmm_constraint_t cnst;
  36
  37   l = xbt_new0(s_lmm_system_t, 1);
  38
  39   l->modified = 0;
  40   l->selective_update_active = sg_maxmin_selective_update;
  41
  42   XBT_DEBUG("Setting selective_update_active flag to %d\n",
  43          l->selective_update_active);
  44
  45   xbt_swag_init(&(l->variable_set),
  46                 xbt_swag_offset(var, variable_set_hookup));
  47   xbt_swag_init(&(l->constraint_set),
  48                 xbt_swag_offset(cnst, constraint_set_hookup));
  49
  50   xbt_swag_init(&(l->active_constraint_set),
  51                 xbt_swag_offset(cnst, active_constraint_set_hookup));
  52
  53   xbt_swag_init(&(l->modified_constraint_set),
  54                 xbt_swag_offset(cnst, modified_constraint_set_hookup));
  55   xbt_swag_init(&(l->saturated_variable_set),
  56                 xbt_swag_offset(var, saturated_variable_set_hookup));
  57   xbt_swag_init(&(l->saturated_constraint_set),
  58                 xbt_swag_offset(cnst, saturated_constraint_set_hookup));
  59
  60   l->variable_mallocator = xbt_mallocator_new(65536,
  61                                               lmm_variable_mallocator_new_f,
  62                                               lmm_variable_mallocator_free_f,
  63                                               lmm_variable_mallocator_reset_f);
  64
  65   return l;
  66 }
  67
  68 void lmm_system_free(lmm_system_t sys)
  69 {
  70   lmm_variable_t var = NULL;
  71   lmm_constraint_t cnst = NULL;
  72
  73   while ((var = extract_variable(sys))) {
  74     XBT_WARN
  75         ("Variable %p (%d) still in LMM system when freing it: this may be a bug",
  76          var, var->id_int);
  77     lmm_var_free(sys, var);
  78   }
  79
  80   while ((cnst = extract_constraint(sys)))
  81     lmm_cnst_free(sys, cnst);
  82
  83   xbt_mallocator_free(sys->variable_mallocator);
  84   free(sys);
  85 }
  86
  87 XBT_INLINE void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  88 {
  89   int i;
  90   lmm_element_t elem = NULL;
  91
  92   XBT_IN("(sys=%p, var=%p)", sys, var);
  93   sys->modified = 1;
  94
  95   for (i = 0; i < var->cnsts_number; i++) {
  96     elem = &var->cnsts[i];
  97     xbt_swag_remove(elem, &(elem->constraint->element_set));
  98     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
  99     if (!xbt_swag_size(&(elem->constraint->element_set)))
 100       make_constraint_inactive(sys, elem->constraint);
 101     else
 102       lmm_update_modified_set(sys, elem->constraint);
 103   }
 104   var->cnsts_number = 0;
 105   XBT_OUT();
 106 }
 107
 108 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
 109 {
 110
 111   lmm_variable_disable(sys, var);
 112   xbt_mallocator_release(sys->variable_mallocator, var);
 113 }
 114
 115 static XBT_INLINE void lmm_cnst_free(lmm_system_t sys,
 116                                      lmm_constraint_t cnst)
 117 {
 118 /*   xbt_assert(xbt_swag_size(&(cnst->element_set)), */
 119 /*            "This list should be empty!"); */
 120   remove_active_constraint(sys, cnst);
 121   free(cnst);
 122 }
 123
 124 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 125                                     double bound_value)
 126 {
 127   lmm_constraint_t cnst = NULL;
 128   s_lmm_element_t elem;
 129
 130   cnst = xbt_new0(s_lmm_constraint_t, 1);
 131   cnst->id = id;
 132   cnst->id_int = Global_const_debug_id++;
 133   xbt_swag_init(&(cnst->element_set),
 134                 xbt_swag_offset(elem, element_set_hookup));
 135   xbt_swag_init(&(cnst->active_element_set),
 136                 xbt_swag_offset(elem, active_element_set_hookup));
 137
 138   cnst->bound = bound_value;
 139   cnst->usage = 0;
 140   cnst->shared = 1;
 141   insert_constraint(sys, cnst);
 142
 143   return cnst;
 144 }
 145
 146 XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
 147 {
 148   cnst->shared = 0;
 149 }
 150
 151 XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
 152 {
 153   return (cnst->shared);
 154 }
 155
 156 XBT_INLINE void lmm_constraint_free(lmm_system_t sys,
 157                                     lmm_constraint_t cnst)
 158 {
 159   remove_constraint(sys, cnst);
 160   lmm_cnst_free(sys, cnst);
 161 }
 162
 163 static void *lmm_variable_mallocator_new_f(void)
 164 {
 165   lmm_variable_t var = xbt_new(s_lmm_variable_t, 1);
 166   var->cnsts = NULL; /* will be created by realloc */
 167   return var;
 168 }
 169
 170 static void lmm_variable_mallocator_free_f(void *var)
 171 {
 172   xbt_free(((lmm_variable_t) var)->cnsts);
 173   xbt_free(var);
 174 }
 175
 176 static void lmm_variable_mallocator_reset_f(void *var)
 177 {
 178   /* lmm_variable_new() initializes everything */
 179 }
 180
 181 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 182                                 double weight,
 183                                 double bound, int number_of_constraints)
 184 {
 185   lmm_variable_t var = NULL;
 186   int i;
 187
 188   XBT_IN("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 189           sys, id, weight, bound, number_of_constraints);
 190
 191   var = xbt_mallocator_get(sys->variable_mallocator);
 192   var->id = id;
 193   var->id_int = Global_debug_id++;
 194   var->cnsts = xbt_realloc(var->cnsts, number_of_constraints * sizeof(s_lmm_element_t));
 195   for (i = 0; i < number_of_constraints; i++) {
 196     var->cnsts[i].element_set_hookup.next = NULL;
 197     var->cnsts[i].element_set_hookup.prev = NULL;
 198     var->cnsts[i].active_element_set_hookup.next = NULL;
 199     var->cnsts[i].active_element_set_hookup.prev = NULL;
 200     var->cnsts[i].constraint = NULL;
 201     var->cnsts[i].variable = NULL;
 202     var->cnsts[i].value = 0.0;
 203   }
 204   var->cnsts_size = number_of_constraints;
 205   var->cnsts_number = 0;
 206   var->weight = weight;
 207   var->bound = bound;
 208   var->value = 0.0;
 209
 210   var->mu = 0.0;
 211   var->new_mu = 0.0;
 212   var->func_f = func_f_def;
 213   var->func_fp = func_fp_def;
 214   var->func_fpi = func_fpi_def;
 215
 216   var->variable_set_hookup.next = NULL;
 217   var->variable_set_hookup.prev = NULL;
 218   var->saturated_variable_set_hookup.next = NULL;
 219   var->saturated_variable_set_hookup.prev = NULL;
 220
 221   if (weight)
 222     xbt_swag_insert_at_head(var, &(sys->variable_set));
 223   else
 224     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 225   XBT_OUT();
 226   return var;
 227 }
 228
 229 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 230 {
 231   remove_variable(sys, var);
 232   lmm_var_free(sys, var);
 233 }
 234
 235 XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 236 {
 237   return (var->value);
 238 }
 239
 240 XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
 241 {
 242   return (var->bound);
 243 }
 244
 245 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 246                 lmm_variable_t var, double value)
 247 {
 248   lmm_element_t elem = NULL;
 249
 250   sys->modified = 1;
 251
 252   xbt_assert(var->cnsts_number < var->cnsts_size, "Too much constraints");
 253
 254   elem = &(var->cnsts[var->cnsts_number++]);
 255
 256   elem->value = value;
 257   elem->constraint = cnst;
 258   elem->variable = var;
 259
 260   if (var->weight)
 261     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 262   else
 263     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 264
 265   make_constraint_active(sys, cnst);
 266   lmm_update_modified_set(sys, cnst);
 267 }
 268
 269 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 270                     lmm_variable_t var, double value)
 271 {
 272   int i;
 273   sys->modified = 1;
 274
 275   for (i = 0; i < var->cnsts_number; i++)
 276     if (var->cnsts[i].constraint == cnst)
 277       break;
 278
 279   if (i < var->cnsts_number) {
 280     if (cnst->shared)
 281       var->cnsts[i].value += value;
 282     else
 283       var->cnsts[i].value = MAX(var->cnsts[i].value, value);
 284     lmm_update_modified_set(sys, cnst);
 285   } else
 286     lmm_expand(sys, cnst, var, value);
 287 }
 288
 289 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 290                         lmm_variable_t var, double value)
 291 {
 292   int i;
 293
 294   for (i = 0; i < var->cnsts_number; i++)
 295     if (var->cnsts[i].constraint == cnst)
 296       break;
 297
 298   if (i < var->cnsts_number) {
 299     var->cnsts[i].value = value;
 300     sys->modified = 1;
 301     lmm_update_modified_set(sys, cnst);
 302   } else
 303     DIE_IMPOSSIBLE;
 304 }
 305
 306 XBT_INLINE lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 307                                                   lmm_variable_t var,
 308                                                   int num)
 309 {
 310   if (num < var->cnsts_number)
 311     return (var->cnsts[num].constraint);
 312   else
 313     return NULL;
 314 }
 315
 316 XBT_INLINE int lmm_get_number_of_cnst_from_var(lmm_system_t sys,
 317                                                lmm_variable_t var)
 318 {
 319   return (var->cnsts_number);
 320 }
 321
 322 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 323                                      lmm_constraint_t cnst,
 324                                      lmm_element_t * elem)
 325 {
 326   if (!(*elem))
 327     *elem = xbt_swag_getFirst(&(cnst->element_set));
 328   else
 329     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 330   if (*elem)
 331     return (*elem)->variable;
 332   else
 333     return NULL;
 334 }
 335
 336 XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 337 {
 338   return cnst->id;
 339 }
 340
 341 XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 342 {
 343   return var->id;
 344 }
 345
 346 static XBT_INLINE void saturated_constraint_set_update(lmm_system_t sys,
 347                                                        lmm_constraint_t
 348                                                        cnst,
 349                                                        double *min_usage)
 350 {
 351   lmm_constraint_t useless_cnst = NULL;
 352
 353   XBT_IN("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 354   if (cnst->usage <= 0) {
 355     XBT_OUT();
 356     return;
 357   }
 358   if (cnst->remaining <= 0) {
 359     XBT_OUT();
 360     return;
 361   }
 362   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 363     *min_usage = cnst->remaining / cnst->usage;
 364     XBT_LOG(xbt_log_priority_trace,
 365          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 366          cnst->remaining, cnst->usage);
 367     while ((useless_cnst =
 368             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 369       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 370
 371     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 372   } else if (*min_usage == cnst->remaining / cnst->usage) {
 373     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 374   }
 375   XBT_OUT();
 376 }
 377
 378 static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 379 {
 380   lmm_constraint_t cnst = NULL;
 381   xbt_swag_t cnst_list = NULL;
 382   lmm_element_t elem = NULL;
 383   xbt_swag_t elem_list = NULL;
 384
 385   cnst_list = &(sys->saturated_constraint_set);
 386   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 387     elem_list = &(cnst->active_element_set);
 388     xbt_swag_foreach(elem, elem_list) {
 389       if (elem->variable->weight <= 0)
 390         break;
 391       if ((elem->value > 0))
 392         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 393     }
 394     xbt_swag_remove(cnst, cnst_list);
 395   }
 396 }
 397
 398 void lmm_print(lmm_system_t sys)
 399 {
 400   lmm_constraint_t cnst = NULL;
 401   lmm_element_t elem = NULL;
 402   lmm_variable_t var = NULL;
 403   xbt_swag_t cnst_list = NULL;
 404   xbt_swag_t var_list = NULL;
 405   xbt_swag_t elem_list = NULL;
 406   char print_buf[1024];
 407   char *trace_buf = xbt_malloc0(sizeof(char));
 408   double sum = 0.0;
 409
 410   /* Printing Objective */
 411   var_list = &(sys->variable_set);
 412   sprintf(print_buf, "MAX-MIN ( ");
 413   trace_buf =
 414       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 415   strcat(trace_buf, print_buf);
 416   xbt_swag_foreach(var, var_list) {
 417     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 418     trace_buf =
 419         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 420     strcat(trace_buf, print_buf);
 421   }
 422   sprintf(print_buf, ")");
 423   trace_buf =
 424       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 425   strcat(trace_buf, print_buf);
 426   fprintf(stderr, "%s", trace_buf);
 427   //XBT_DEBUG("%20s", trace_buf); FIXME
 428   trace_buf[0] = '\000';
 429
 430   XBT_DEBUG("Constraints");
 431   /* Printing Constraints */
 432   cnst_list = &(sys->active_constraint_set);
 433   xbt_swag_foreach(cnst, cnst_list) {
 434     sum = 0.0;
 435     elem_list = &(cnst->element_set);
 436     sprintf(print_buf, "\t");
 437     trace_buf =
 438         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 439     strcat(trace_buf, print_buf);
 440     sprintf(print_buf, "%s(",(cnst->shared)?"":"max");
 441     trace_buf =
 442       xbt_realloc(trace_buf,
 443                   strlen(trace_buf) + strlen(print_buf) + 1);
 444     strcat(trace_buf, print_buf);
 445     xbt_swag_foreach(elem, elem_list) {
 446       sprintf(print_buf, "%f.'%d'(%f) %s ", elem->value,
 447               elem->variable->id_int, elem->variable->value,(cnst->shared)?"+":",");
 448       trace_buf =
 449           xbt_realloc(trace_buf,
 450                       strlen(trace_buf) + strlen(print_buf) + 1);
 451       strcat(trace_buf, print_buf);
 452       if(cnst->shared)
 453         sum += elem->value * elem->variable->value;
 454       else
 455         sum = MAX(sum,elem->value * elem->variable->value);
 456     }
 457     sprintf(print_buf, "0) <= %f ('%d')", cnst->bound, cnst->id_int);
 458     trace_buf =
 459         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 460     strcat(trace_buf, print_buf);
 461
 462     if (!cnst->shared) {
 463       sprintf(print_buf, " [MAX-Constraint]");
 464       trace_buf =
 465           xbt_realloc(trace_buf,
 466                       strlen(trace_buf) + strlen(print_buf) + 1);
 467       strcat(trace_buf, print_buf);
 468     }
 469     //   XBT_DEBUG("%s", trace_buf);
 470     fprintf(stderr, "%s\n", trace_buf);
 471     trace_buf[0] = '\000';
 472     xbt_assert(!double_positive(sum - cnst->bound),
 473                 "Incorrect value (%f is not smaller than %f): %g",
 474                 sum, cnst->bound, sum - cnst->bound);
 475   }
 476
 477   XBT_DEBUG("Variables");
 478   /* Printing Result */
 479   xbt_swag_foreach(var, var_list) {
 480     if (var->bound > 0) {
 481       XBT_DEBUG("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 482              var->bound);
 483       xbt_assert(!double_positive(var->value - var->bound),
 484                   "Incorrect value (%f is not smaller than %f",
 485                   var->value, var->bound);
 486     } else {
 487       XBT_DEBUG("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 488     }
 489   }
 490
 491   free(trace_buf);
 492 }
 493
 494 void lmm_solve(lmm_system_t sys)
 495 {
 496   lmm_variable_t var = NULL;
 497   lmm_constraint_t cnst = NULL;
 498   lmm_element_t elem = NULL;
 499   xbt_swag_t cnst_list = NULL;
 500   xbt_swag_t var_list = NULL;
 501   xbt_swag_t elem_list = NULL;
 502   double min_usage = -1;
 503   double min_bound = -1;
 504
 505   if (!(sys->modified))
 506     return;
 507
 508   XBT_IN("(sys=%p)", sys);
 509
 510   /*
 511    * Compute Usage and store the variables that reach the maximum.
 512    */
 513   cnst_list =
 514       sys->
 515       selective_update_active ? &(sys->modified_constraint_set) :
 516       &(sys->active_constraint_set);
 517
 518   XBT_DEBUG("Active constraints : %d", xbt_swag_size(cnst_list));
 519   /* Init: Only modified code portions */
 520   xbt_swag_foreach(cnst, cnst_list) {
 521     elem_list = &(cnst->element_set);
 522     //XBT_DEBUG("Variable set : %d", xbt_swag_size(elem_list));
 523     xbt_swag_foreach(elem, elem_list) {
 524       var = elem->variable;
 525       if (var->weight <= 0.0)
 526         break;
 527       var->value = 0.0;
 528     }
 529   }
 530
 531   xbt_swag_foreach(cnst, cnst_list) {
 532     /* INIT */
 533     cnst->remaining = cnst->bound;
 534     if (cnst->remaining == 0)
 535       continue;
 536     cnst->usage = 0;
 537     elem_list = &(cnst->element_set);
 538     xbt_swag_foreach(elem, elem_list) {
 539       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 540       if (elem->variable->weight <= 0)
 541         break;
 542       if ((elem->value > 0)) {
 543         if (cnst->shared)
 544           cnst->usage += elem->value / elem->variable->weight;
 545         else if (cnst->usage < elem->value / elem->variable->weight)
 546           cnst->usage = elem->value / elem->variable->weight;
 547
 548         make_elem_active(elem);
 549         if(keep_track){
 550             xbt_swag_insert((elem->variable)->id, keep_track);
 551         }
 552       }
 553     }
 554     XBT_DEBUG("Constraint Usage '%d' : %f", cnst->id_int, cnst->usage);
 555     /* Saturated constraints update */
 556     saturated_constraint_set_update(sys, cnst, &min_usage);
 557   }
 558   saturated_variable_set_update(sys);
 559
 560   /* Saturated variables update */
 561
 562   do {
 563     /* Fix the variables that have to be */
 564     var_list = &(sys->saturated_variable_set);
 565
 566     xbt_swag_foreach(var, var_list) {
 567       if (var->weight <= 0.0)
 568         DIE_IMPOSSIBLE;
 569       /* First check if some of these variables have reach their upper
 570          bound and update min_usage accordingly. */
 571       XBT_DEBUG
 572           ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 573            var->id_int, var->bound, var->weight, min_usage,
 574            var->bound * var->weight);
 575       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 576         if (min_bound < 0)
 577           min_bound = var->bound;
 578         else
 579           min_bound = MIN(min_bound, var->bound);
 580         XBT_DEBUG("Updated min_bound=%f", min_bound);
 581       }
 582     }
 583
 584
 585     while ((var = xbt_swag_getFirst(var_list))) {
 586       int i;
 587
 588       if (min_bound < 0) {
 589         var->value = min_usage / var->weight;
 590       } else {
 591         if (min_bound == var->bound)
 592           var->value = var->bound;
 593         else {
 594           xbt_swag_remove(var, var_list);
 595           continue;
 596         }
 597       }
 598       XBT_DEBUG("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 599              min_usage, var->id_int, var->weight, var->id_int, var->value);
 600
 601
 602       /* Update usage */
 603
 604       for (i = 0; i < var->cnsts_number; i++) {
 605         elem = &var->cnsts[i];
 606         cnst = elem->constraint;
 607         if (cnst->shared) {
 608           double_update(&(cnst->remaining), elem->value * var->value);
 609           double_update(&(cnst->usage), elem->value / var->weight);
 610           make_elem_inactive(elem);
 611         } else {                /* FIXME one day: We recompute usage.... :( */
 612           cnst->usage = 0.0;
 613           make_elem_inactive(elem);
 614           elem_list = &(cnst->element_set);
 615           xbt_swag_foreach(elem, elem_list) {
 616             if (elem->variable->weight <= 0)
 617               break;
 618             if (elem->variable->value > 0)
 619               break;
 620             if ((elem->value > 0)) {
 621               cnst->usage =
 622                   MAX(cnst->usage, elem->value / elem->variable->weight);
 623               XBT_DEBUG("Constraint Usage %d : %f", cnst->id_int,
 624                      cnst->usage);
 625               make_elem_active(elem);
 626             }
 627           }
 628         }
 629       }
 630       xbt_swag_remove(var, var_list);
 631     }
 632
 633     /* Find out which variables reach the maximum */
 634     cnst_list =
 635         sys->selective_update_active ? &(sys->modified_constraint_set) :
 636         &(sys->active_constraint_set);
 637     min_usage = -1;
 638     min_bound = -1;
 639     xbt_swag_foreach(cnst, cnst_list) {
 640       saturated_constraint_set_update(sys, cnst, &min_usage);
 641     }
 642     saturated_variable_set_update(sys);
 643
 644   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 645
 646   sys->modified = 0;
 647   if (sys->selective_update_active)
 648     lmm_remove_all_modified_set(sys);
 649
 650   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 651     lmm_print(sys);
 652   }
 653   XBT_OUT();
 654 }
 655
 656 /* Not a O(1) function */
 657
 658 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 659                 lmm_variable_t var, double value)
 660 {
 661   int i;
 662
 663   for (i = 0; i < var->cnsts_number; i++)
 664     if (var->cnsts[i].constraint == cnst) {
 665       var->cnsts[i].value = value;
 666       sys->modified = 1;
 667       lmm_update_modified_set(sys, cnst);
 668       return;
 669     }
 670 }
 671
 672 /** \brief Attribute the value bound to var->bound.
 673  *
 674  *  \param sys the lmm_system_t
 675  *  \param var the lmm_variable_t
 676  *  \param bound the new bound to associate with var
 677  *
 678  *  Makes var->bound equal to bound. Whenever this function is called
 679  *  a change is  signed in the system. To
 680  *  avoid false system changing detection it is a good idea to test
 681  *  (bound != 0) before calling it.
 682  *
 683  */
 684 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 685                                double bound)
 686 {
 687   int i;
 688
 689   sys->modified = 1;
 690   var->bound = bound;
 691
 692   for (i = 0; i < var->cnsts_number; i++)
 693     lmm_update_modified_set(sys, var->cnsts[i].constraint);
 694
 695 }
 696
 697
 698 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 699                                 double weight)
 700 {
 701   int i;
 702   lmm_element_t elem;
 703
 704   if (weight == var->weight)
 705     return;
 706   XBT_IN("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 707   sys->modified = 1;
 708   var->weight = weight;
 709   xbt_swag_remove(var, &(sys->variable_set));
 710   if (weight)
 711     xbt_swag_insert_at_head(var, &(sys->variable_set));
 712   else
 713     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 714
 715   for (i = 0; i < var->cnsts_number; i++) {
 716     elem = &var->cnsts[i];
 717     xbt_swag_remove(elem, &(elem->constraint->element_set));
 718     if (weight)
 719       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 720     else
 721       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 722
 723     lmm_update_modified_set(sys, elem->constraint);
 724   }
 725   if (!weight)
 726     var->value = 0.0;
 727
 728   XBT_OUT();
 729 }
 730
 731 XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 732 {
 733   return var->weight;
 734 }
 735
 736 XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys,
 737                                             lmm_constraint_t cnst,
 738                                             double bound)
 739 {
 740   sys->modified = 1;
 741   lmm_update_modified_set(sys, cnst);
 742   cnst->bound = bound;
 743 }
 744
 745 XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 746 {
 747   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 748 }
 749
 750 XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t
 751                                                             sys)
 752 {
 753   return xbt_swag_getFirst(&(sys->active_constraint_set));
 754 }
 755
 756 XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t
 757                                                            sys,
 758                                                            lmm_constraint_t
 759                                                            cnst)
 760 {
 761   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 762 }
 763
 764 #ifdef HAVE_LATENCY_BOUND_TRACKING
 765 XBT_INLINE int lmm_is_variable_limited_by_latency(lmm_variable_t var)
 766 {
 767   return (double_equals(var->bound, var->value));
 768 }
 769 #endif
 770
 771
 772 /** \brief Update the constraint set propagating recursively to
 773  *  other constraints so the system should not be entirely computed.
 774  *
 775  *  \param sys the lmm_system_t
 776  *  \param cnst the lmm_constraint_t affected by the change
 777  *
 778  *  A recursive algorithm to optimize the system recalculation selecting only
 779  *  constraints that have changed. Each constraint change is propagated
 780  *  to the list of constraints for each variable.
 781  */
 782 static void lmm_update_modified_set(lmm_system_t sys,
 783                                     lmm_constraint_t cnst)
 784 {
 785   lmm_element_t elem = NULL;
 786   lmm_variable_t var = NULL;
 787   xbt_swag_t elem_list = NULL;
 788   int i;
 789
 790   /* return if selective update isn't active */
 791   if (!sys->selective_update_active)
 792     return;
 793
 794   //XBT_DEBUG("Updating modified constraint set with constraint %d", cnst->id_int);
 795
 796   if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
 797     return;
 798
 799   //XBT_DEBUG("Inserting into modified constraint set %d", cnst->id_int);
 800
 801   /* add to modified set */
 802   xbt_swag_insert(cnst, &(sys->modified_constraint_set));
 803
 804   elem_list = &(cnst->element_set);
 805   xbt_swag_foreach(elem, elem_list) {
 806     var = elem->variable;
 807     for (i = 0; i < var->cnsts_number; i++)
 808       if (cnst != var->cnsts[i].constraint) {
 809         //XBT_DEBUG("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
 810         lmm_update_modified_set(sys, var->cnsts[i].constraint);
 811       }
 812   }
 813 }
 814
 815 /** \brief Remove all constraints of the modified_constraint_set.
 816  *
 817  *  \param sys the lmm_system_t
 818  */
 819 static void lmm_remove_all_modified_set(lmm_system_t sys)
 820 {
 821   lmm_element_t elem = NULL;
 822   lmm_element_t elem_next = NULL;
 823   xbt_swag_t elem_list = NULL;
 824
 825   elem_list = &(sys->modified_constraint_set);
 826   xbt_swag_foreach_safe(elem, elem_next, elem_list) {
 827     xbt_swag_remove(elem, elem_list);
 828   }
 829 }