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 int lmm_get_number_of_cnst_from_var(lmm_system_t sys,
 324                                                lmm_variable_t var)
 325 {
 326   return (var->cnsts_number);
 327 }
 328
 329 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 330                                      lmm_constraint_t cnst,
 331                                      lmm_element_t * elem)
 332 {
 333   if (!(*elem))
 334     *elem = xbt_swag_getFirst(&(cnst->element_set));
 335   else
 336     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 337   if (*elem)
 338     return (*elem)->variable;
 339   else
 340     return NULL;
 341 }
 342
 343 XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 344 {
 345   return cnst->id;
 346 }
 347
 348 XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 349 {
 350   return var->id;
 351 }
 352
 353 static XBT_INLINE void saturated_constraint_set_update(lmm_system_t sys,
 354                                                        lmm_constraint_t
 355                                                        cnst,
 356                                                        double *min_usage)
 357 {
 358   lmm_constraint_t useless_cnst = NULL;
 359
 360   XBT_IN("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 361   if (cnst->usage <= 0) {
 362     XBT_OUT();
 363     return;
 364   }
 365   if (cnst->remaining <= 0) {
 366     XBT_OUT();
 367     return;
 368   }
 369   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 370     *min_usage = cnst->remaining / cnst->usage;
 371     XBT_LOG(xbt_log_priority_trace,
 372          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 373          cnst->remaining, cnst->usage);
 374     while ((useless_cnst =
 375             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 376       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 377
 378     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 379   } else if (*min_usage == cnst->remaining / cnst->usage) {
 380     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 381   }
 382   XBT_OUT();
 383 }
 384
 385 static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 386 {
 387   lmm_constraint_t cnst = NULL;
 388   xbt_swag_t cnst_list = NULL;
 389   lmm_element_t elem = NULL;
 390   xbt_swag_t elem_list = NULL;
 391
 392   cnst_list = &(sys->saturated_constraint_set);
 393   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 394     elem_list = &(cnst->active_element_set);
 395     xbt_swag_foreach(elem, elem_list) {
 396       if (elem->variable->weight <= 0)
 397         break;
 398       if ((elem->value > 0))
 399         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 400     }
 401     xbt_swag_remove(cnst, cnst_list);
 402   }
 403 }
 404
 405 void lmm_print(lmm_system_t sys)
 406 {
 407   lmm_constraint_t cnst = NULL;
 408   lmm_element_t elem = NULL;
 409   lmm_variable_t var = NULL;
 410   xbt_swag_t cnst_list = NULL;
 411   xbt_swag_t var_list = NULL;
 412   xbt_swag_t elem_list = NULL;
 413   char print_buf[1024];
 414   char *trace_buf = xbt_malloc0(sizeof(char));
 415   double sum = 0.0;
 416
 417   /* Printing Objective */
 418   var_list = &(sys->variable_set);
 419   sprintf(print_buf, "MAX-MIN ( ");
 420   trace_buf =
 421       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 422   strcat(trace_buf, print_buf);
 423   xbt_swag_foreach(var, var_list) {
 424     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 425     trace_buf =
 426         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 427     strcat(trace_buf, print_buf);
 428   }
 429   sprintf(print_buf, ")");
 430   trace_buf =
 431       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 432   strcat(trace_buf, print_buf);
 433   XBT_DEBUG("%20s", trace_buf);
 434   trace_buf[0] = '\000';
 435
 436   XBT_DEBUG("Constraints");
 437   /* Printing Constraints */
 438   cnst_list = &(sys->active_constraint_set);
 439   xbt_swag_foreach(cnst, cnst_list) {
 440     sum = 0.0;
 441     elem_list = &(cnst->element_set);
 442     sprintf(print_buf, "\t");
 443     trace_buf =
 444         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 445     strcat(trace_buf, print_buf);
 446     sprintf(print_buf, "%s(",(cnst->shared)?"":"max");
 447     trace_buf =
 448       xbt_realloc(trace_buf,
 449                   strlen(trace_buf) + strlen(print_buf) + 1);
 450     strcat(trace_buf, print_buf);
 451     xbt_swag_foreach(elem, elem_list) {
 452       sprintf(print_buf, "%f.'%d'(%f) %s ", elem->value,
 453               elem->variable->id_int, elem->variable->value,(cnst->shared)?"+":",");
 454       trace_buf =
 455           xbt_realloc(trace_buf,
 456                       strlen(trace_buf) + strlen(print_buf) + 1);
 457       strcat(trace_buf, print_buf);
 458       if(cnst->shared)
 459         sum += elem->value * elem->variable->value;
 460       else
 461         sum = MAX(sum,elem->value * elem->variable->value);
 462     }
 463     sprintf(print_buf, "0) <= %f ('%d')", cnst->bound, cnst->id_int);
 464     trace_buf =
 465         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 466     strcat(trace_buf, print_buf);
 467
 468     if (!cnst->shared) {
 469       sprintf(print_buf, " [MAX-Constraint]");
 470       trace_buf =
 471           xbt_realloc(trace_buf,
 472                       strlen(trace_buf) + strlen(print_buf) + 1);
 473       strcat(trace_buf, print_buf);
 474     }
 475     XBT_DEBUG("%s", trace_buf);
 476     trace_buf[0] = '\000';
 477     xbt_assert(!double_positive(sum - cnst->bound),
 478                 "Incorrect value (%f is not smaller than %f): %g",
 479                 sum, cnst->bound, sum - cnst->bound);
 480   }
 481
 482   XBT_DEBUG("Variables");
 483   /* Printing Result */
 484   xbt_swag_foreach(var, var_list) {
 485     if (var->bound > 0) {
 486       XBT_DEBUG("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 487              var->bound);
 488       xbt_assert(!double_positive(var->value - var->bound),
 489                   "Incorrect value (%f is not smaller than %f",
 490                   var->value, var->bound);
 491     } else {
 492       XBT_DEBUG("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 493     }
 494   }
 495
 496   free(trace_buf);
 497 }
 498
 499 void lmm_solve(lmm_system_t sys)
 500 {
 501   lmm_variable_t var = NULL;
 502   lmm_constraint_t cnst = NULL;
 503   lmm_element_t elem = NULL;
 504   xbt_swag_t cnst_list = NULL;
 505   xbt_swag_t var_list = NULL;
 506   xbt_swag_t elem_list = NULL;
 507   double min_usage = -1;
 508   double min_bound = -1;
 509
 510   if (!(sys->modified))
 511     return;
 512
 513   XBT_IN("(sys=%p)", sys);
 514
 515   /*
 516    * Compute Usage and store the variables that reach the maximum.
 517    */
 518   cnst_list =
 519       sys->
 520       selective_update_active ? &(sys->modified_constraint_set) :
 521       &(sys->active_constraint_set);
 522
 523   XBT_DEBUG("Active constraints : %d", xbt_swag_size(cnst_list));
 524   /* Init: Only modified code portions */
 525   xbt_swag_foreach(cnst, cnst_list) {
 526     elem_list = &(cnst->element_set);
 527     //XBT_DEBUG("Variable set : %d", xbt_swag_size(elem_list));
 528     xbt_swag_foreach(elem, elem_list) {
 529       var = elem->variable;
 530       if (var->weight <= 0.0)
 531         break;
 532       var->value = 0.0;
 533     }
 534   }
 535
 536   xbt_swag_foreach(cnst, cnst_list) {
 537     /* INIT */
 538     cnst->remaining = cnst->bound;
 539     if (cnst->remaining == 0)
 540       continue;
 541     cnst->usage = 0;
 542     elem_list = &(cnst->element_set);
 543     xbt_swag_foreach(elem, elem_list) {
 544       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 545       if (elem->variable->weight <= 0)
 546         break;
 547       if ((elem->value > 0)) {
 548         if (cnst->shared)
 549           cnst->usage += elem->value / elem->variable->weight;
 550         else if (cnst->usage < elem->value / elem->variable->weight)
 551           cnst->usage = elem->value / elem->variable->weight;
 552
 553         make_elem_active(elem);
 554         if (sys->keep_track)
 555           xbt_swag_insert(elem->variable->id, sys->keep_track);
 556       }
 557     }
 558     XBT_DEBUG("Constraint Usage '%d' : %f", cnst->id_int, cnst->usage);
 559     /* Saturated constraints update */
 560     saturated_constraint_set_update(sys, cnst, &min_usage);
 561   }
 562   saturated_variable_set_update(sys);
 563
 564   /* Saturated variables update */
 565
 566   do {
 567     /* Fix the variables that have to be */
 568     var_list = &(sys->saturated_variable_set);
 569
 570     xbt_swag_foreach(var, var_list) {
 571       if (var->weight <= 0.0)
 572         DIE_IMPOSSIBLE;
 573       /* First check if some of these variables have reach their upper
 574          bound and update min_usage accordingly. */
 575       XBT_DEBUG
 576           ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 577            var->id_int, var->bound, var->weight, min_usage,
 578            var->bound * var->weight);
 579       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 580         if (min_bound < 0)
 581           min_bound = var->bound;
 582         else
 583           min_bound = MIN(min_bound, var->bound);
 584         XBT_DEBUG("Updated min_bound=%f", min_bound);
 585       }
 586     }
 587
 588
 589     while ((var = xbt_swag_getFirst(var_list))) {
 590       int i;
 591
 592       if (min_bound < 0) {
 593         var->value = min_usage / var->weight;
 594       } else {
 595         if (min_bound == var->bound)
 596           var->value = var->bound;
 597         else {
 598           xbt_swag_remove(var, var_list);
 599           continue;
 600         }
 601       }
 602       XBT_DEBUG("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 603              min_usage, var->id_int, var->weight, var->id_int, var->value);
 604
 605
 606       /* Update usage */
 607
 608       for (i = 0; i < var->cnsts_number; i++) {
 609         elem = &var->cnsts[i];
 610         cnst = elem->constraint;
 611         if (cnst->shared) {
 612           double_update(&(cnst->remaining), elem->value * var->value);
 613           double_update(&(cnst->usage), elem->value / var->weight);
 614           make_elem_inactive(elem);
 615         } else {                /* FIXME one day: We recompute usage.... :( */
 616           cnst->usage = 0.0;
 617           make_elem_inactive(elem);
 618           elem_list = &(cnst->element_set);
 619           xbt_swag_foreach(elem, elem_list) {
 620             if (elem->variable->weight <= 0)
 621               break;
 622             if (elem->variable->value > 0)
 623               break;
 624             if ((elem->value > 0)) {
 625               cnst->usage =
 626                   MAX(cnst->usage, elem->value / elem->variable->weight);
 627               XBT_DEBUG("Constraint Usage %d : %f", cnst->id_int,
 628                      cnst->usage);
 629               make_elem_active(elem);
 630             }
 631           }
 632         }
 633       }
 634       xbt_swag_remove(var, var_list);
 635     }
 636
 637     /* Find out which variables reach the maximum */
 638     min_usage = -1;
 639     min_bound = -1;
 640     xbt_swag_foreach(cnst, cnst_list) {
 641       saturated_constraint_set_update(sys, cnst, &min_usage);
 642     }
 643     saturated_variable_set_update(sys);
 644
 645   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 646
 647   sys->modified = 0;
 648   if (sys->selective_update_active)
 649     lmm_remove_all_modified_set(sys);
 650
 651   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 652     lmm_print(sys);
 653   }
 654   XBT_OUT();
 655 }
 656
 657 /* Not a O(1) function */
 658
 659 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 660                 lmm_variable_t var, double value)
 661 {
 662   int i;
 663
 664   for (i = 0; i < var->cnsts_number; i++)
 665     if (var->cnsts[i].constraint == cnst) {
 666       var->cnsts[i].value = value;
 667       sys->modified = 1;
 668       lmm_update_modified_set(sys, cnst);
 669       return;
 670     }
 671 }
 672
 673 /** \brief Attribute the value bound to var->bound.
 674  *
 675  *  \param sys the lmm_system_t
 676  *  \param var the lmm_variable_t
 677  *  \param bound the new bound to associate with var
 678  *
 679  *  Makes var->bound equal to bound. Whenever this function is called
 680  *  a change is  signed in the system. To
 681  *  avoid false system changing detection it is a good idea to test
 682  *  (bound != 0) before calling it.
 683  *
 684  */
 685 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 686                                double bound)
 687 {
 688   sys->modified = 1;
 689   var->bound = bound;
 690
 691   if (var->cnsts_number)
 692     lmm_update_modified_set(sys, var->cnsts[0].constraint);
 693 }
 694
 695
 696 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 697                                 double weight)
 698 {
 699   int i;
 700   lmm_element_t elem;
 701
 702   if (weight == var->weight)
 703     return;
 704   XBT_IN("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 705   sys->modified = 1;
 706   var->weight = weight;
 707   xbt_swag_remove(var, &(sys->variable_set));
 708   if (weight)
 709     xbt_swag_insert_at_head(var, &(sys->variable_set));
 710   else
 711     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 712
 713   for (i = 0; i < var->cnsts_number; i++) {
 714     elem = &var->cnsts[i];
 715     xbt_swag_remove(elem, &(elem->constraint->element_set));
 716     if (weight)
 717       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 718     else
 719       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 720
 721     if (i == 0)
 722       lmm_update_modified_set(sys, elem->constraint);
 723   }
 724   if (!weight)
 725     var->value = 0.0;
 726
 727   XBT_OUT();
 728 }
 729
 730 XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 731 {
 732   return var->weight;
 733 }
 734
 735 XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys,
 736                                             lmm_constraint_t cnst,
 737                                             double bound)
 738 {
 739   sys->modified = 1;
 740   lmm_update_modified_set(sys, cnst);
 741   cnst->bound = bound;
 742 }
 743
 744 XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 745 {
 746   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 747 }
 748
 749 XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t
 750                                                             sys)
 751 {
 752   return xbt_swag_getFirst(&(sys->active_constraint_set));
 753 }
 754
 755 XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t
 756                                                            sys,
 757                                                            lmm_constraint_t
 758                                                            cnst)
 759 {
 760   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 761 }
 762
 763 #ifdef HAVE_LATENCY_BOUND_TRACKING
 764 XBT_INLINE int lmm_is_variable_limited_by_latency(lmm_variable_t var)
 765 {
 766   return (double_equals(var->bound, var->value));
 767 }
 768 #endif
 769
 770
 771 /** \brief Update the constraint set propagating recursively to
 772  *  other constraints so the system should not be entirely computed.
 773  *
 774  *  \param sys the lmm_system_t
 775  *  \param cnst the lmm_constraint_t affected by the change
 776  *
 777  *  A recursive algorithm to optimize the system recalculation selecting only
 778  *  constraints that have changed. Each constraint change is propagated
 779  *  to the list of constraints for each variable.
 780  */
 781 static void lmm_update_modified_set_rec(lmm_system_t sys,
 782                                         lmm_constraint_t cnst)
 783 {
 784   lmm_element_t elem;
 785
 786   xbt_swag_foreach(elem, &cnst->element_set) {
 787     lmm_variable_t var = elem->variable;
 788     s_lmm_element_t *cnsts = var->cnsts;
 789     int i;
 790     for (i = 0; var->visited != sys->visited_counter
 791              && i < var->cnsts_number ; i++) {
 792       if (cnsts[i].constraint != cnst
 793           && !xbt_swag_belongs(cnsts[i].constraint,
 794                                &sys->modified_constraint_set)) {
 795         xbt_swag_insert(cnsts[i].constraint, &sys->modified_constraint_set);
 796         lmm_update_modified_set_rec(sys, cnsts[i].constraint);
 797       }
 798     }
 799     var->visited = sys->visited_counter;
 800   }
 801 }
 802
 803 static void lmm_update_modified_set(lmm_system_t sys,
 804                                     lmm_constraint_t cnst)
 805 {
 806   /* nothing to do if selective update isn't active */
 807   if (sys->selective_update_active
 808       && !xbt_swag_belongs(cnst, &sys->modified_constraint_set)) {
 809     xbt_swag_insert(cnst, &sys->modified_constraint_set);
 810     lmm_update_modified_set_rec(sys, cnst);
 811   }
 812 }
 813
 814 /** \brief Remove all constraints of the modified_constraint_set.
 815  *
 816  *  \param sys the lmm_system_t
 817  */
 818 static void lmm_remove_all_modified_set(lmm_system_t sys)
 819 {
 820   if (++sys->visited_counter == 1) {
 821     /* the counter wrapped around, reset each variable->visited */
 822     lmm_variable_t var;
 823     xbt_swag_foreach(var, &sys->variable_set)
 824       var->visited = 0;
 825   }
 826   xbt_swag_reset(&sys->modified_constraint_set);
 827 }