src/surf/maxmin.c

   1 /*      $Id$     */
   2
   3 /* Copyright (c) 2004 Arnaud Legrand. All rights reserved.                  */
   4
   5 /* This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the license (GNU LGPL) which comes with this package. */
   7
   8
   9 #include "xbt/sysdep.h"
  10 #include "xbt/log.h"
  11 #include "xbt/mallocator.h"
  12 #include "maxmin_private.h"
  13 #include <stdlib.h>
  14 #include <stdio.h> /* sprintf */
  15 #include <math.h>
  16 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
  17                                 "Logging specific to SURF (maxmin)");
  18
  19 static void *lmm_variable_mallocator_new_f(void);
  20 static void lmm_variable_mallocator_free_f(void *var);
  21 static void lmm_variable_mallocator_reset_f(void *var);
  22
  23 lmm_system_t lmm_system_new(void)
  24 {
  25   lmm_system_t l = NULL;
  26   s_lmm_variable_t var;
  27   s_lmm_constraint_t cnst;
  28
  29   l = xbt_new0(s_lmm_system_t, 1);
  30
  31   l->modified = 0;
  32   xbt_swag_init(&(l->variable_set),
  33                 xbt_swag_offset(var, variable_set_hookup));
  34   xbt_swag_init(&(l->constraint_set),
  35                 xbt_swag_offset(cnst, constraint_set_hookup));
  36
  37   xbt_swag_init(&(l->active_constraint_set),
  38                 xbt_swag_offset(cnst, active_constraint_set_hookup));
  39
  40   xbt_swag_init(&(l->saturated_variable_set),
  41                 xbt_swag_offset(var, saturated_variable_set_hookup));
  42   xbt_swag_init(&(l->saturated_constraint_set),
  43                 xbt_swag_offset(cnst, saturated_constraint_set_hookup));
  44
  45   l->variable_mallocator = xbt_mallocator_new(64,
  46                                               lmm_variable_mallocator_new_f,
  47                                               lmm_variable_mallocator_free_f,
  48                                               lmm_variable_mallocator_reset_f);
  49
  50   return l;
  51 }
  52
  53 void lmm_system_free(lmm_system_t sys)
  54 {
  55   lmm_variable_t var = NULL;
  56   lmm_constraint_t cnst = NULL;
  57
  58   while ((var = extract_variable(sys)))
  59     lmm_var_free(sys, var);
  60
  61   while ((cnst = extract_constraint(sys)))
  62     lmm_cnst_free(sys, cnst);
  63
  64   xbt_mallocator_free(sys->variable_mallocator);
  65   free(sys);
  66 }
  67
  68 void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  69 {
  70   int i;
  71   lmm_element_t elem = NULL;
  72
  73   XBT_IN2("(sys=%p, var=%p)", sys, var);
  74   sys->modified = 1;
  75
  76   for (i = 0; i < var->cnsts_number; i++) {
  77     elem = &var->cnsts[i];
  78     xbt_swag_remove(elem, &(elem->constraint->element_set));
  79     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
  80     if (!xbt_swag_size(&(elem->constraint->element_set)))
  81       make_constraint_inactive(sys, elem->constraint);
  82   }
  83   var->cnsts_number = 0;
  84   XBT_OUT;
  85 }
  86
  87 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
  88 {
  89
  90   lmm_variable_disable(sys, var);
  91   free(var->cnsts);
  92   xbt_mallocator_release(sys->variable_mallocator, var);
  93 }
  94
  95 static void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
  96 {
  97 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
  98 /*            "This list should be empty!"); */
  99   remove_active_constraint(sys, cnst);
 100   free(cnst);
 101 }
 102
 103 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 104                                     double bound_value)
 105 {
 106   lmm_constraint_t cnst = NULL;
 107   s_lmm_element_t elem;
 108
 109   cnst = xbt_new0(s_lmm_constraint_t, 1);
 110   cnst->id = id;
 111   xbt_swag_init(&(cnst->element_set),
 112                 xbt_swag_offset(elem, element_set_hookup));
 113   xbt_swag_init(&(cnst->active_element_set),
 114                 xbt_swag_offset(elem, active_element_set_hookup));
 115
 116   cnst->bound = bound_value;
 117   cnst->usage = 0;
 118   cnst->shared = 1;
 119   insert_constraint(sys, cnst);
 120
 121   return cnst;
 122 }
 123
 124 void lmm_constraint_shared(lmm_constraint_t cnst)
 125 {
 126   cnst->shared = 0;
 127 }
 128
 129 void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
 130 {
 131   remove_constraint(sys, cnst);
 132   lmm_cnst_free(sys, cnst);
 133 }
 134
 135 static void *lmm_variable_mallocator_new_f(void)
 136 {
 137   return xbt_new(s_lmm_variable_t, 1);
 138 }
 139
 140 static void lmm_variable_mallocator_free_f(void *var)
 141 {
 142   xbt_free(var);
 143 }
 144
 145 static void lmm_variable_mallocator_reset_f(void *var)
 146 {
 147   /* memset to zero like calloc */
 148   memset(var, 0, sizeof(s_lmm_variable_t));
 149 }
 150
 151 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 152                                 double weight,
 153                                 double bound, int number_of_constraints)
 154 {
 155   lmm_variable_t var = NULL;
 156   int i;
 157
 158   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 159           sys, id, weight, bound, number_of_constraints);
 160
 161   var = xbt_mallocator_get(sys->variable_mallocator);
 162   var->id = id;
 163   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
 164   for (i = 0; i < number_of_constraints; i++) {
 165     /* Should be useless because of the
 166        calloc but it seems to help valgrind... */
 167     var->cnsts[i].element_set_hookup.next = NULL;
 168     var->cnsts[i].element_set_hookup.prev = NULL;
 169     var->cnsts[i].active_element_set_hookup.next = NULL;
 170     var->cnsts[i].active_element_set_hookup.prev = NULL;
 171     var->cnsts[i].constraint = NULL;
 172     var->cnsts[i].variable = NULL;
 173     var->cnsts[i].value = 0.0;
 174   }
 175   var->cnsts_size = number_of_constraints;
 176   var->cnsts_number = 0;        /* Should be useless because of the
 177                                    calloc but it seems to help valgrind... */
 178   var->weight = weight;
 179   var->bound = bound;
 180   var->value = 0.0;
 181   var->df = 0.0;
 182
 183   var->func_f = func_f_def;
 184   var->func_fp = func_fp_def;
 185   var->func_fpi = func_fpi_def;
 186
 187   if (weight)
 188     xbt_swag_insert_at_head(var, &(sys->variable_set));
 189   else
 190     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 191   XBT_OUT;
 192   return var;
 193 }
 194
 195 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 196 {
 197   remove_variable(sys, var);
 198   lmm_var_free(sys, var);
 199 }
 200
 201 double lmm_variable_getvalue(lmm_variable_t var)
 202 {
 203   return (var->value);
 204 }
 205
 206 double lmm_variable_getbound(lmm_variable_t var)
 207 {
 208   return (var->bound);
 209 }
 210
 211 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 212                 lmm_variable_t var, double value)
 213 {
 214   lmm_element_t elem = NULL;
 215
 216   sys->modified = 1;
 217
 218   xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 219
 220   elem = &(var->cnsts[var->cnsts_number++]);
 221
 222   elem->value = value;
 223   elem->constraint = cnst;
 224   elem->variable = var;
 225
 226   if (var->weight)
 227     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 228   else
 229     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 230
 231   make_constraint_active(sys, cnst);
 232 }
 233
 234 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 235                     lmm_variable_t var, double value)
 236 {
 237   int i;
 238   sys->modified = 1;
 239
 240   for (i = 0; i < var->cnsts_number; i++)
 241     if (var->cnsts[i].constraint == cnst)
 242       break;
 243
 244   if (i < var->cnsts_number)
 245     var->cnsts[i].value += value;
 246   else
 247     lmm_expand(sys, cnst, var, value);
 248 }
 249
 250 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 251                         lmm_variable_t var, double value)
 252 {
 253   int i;
 254
 255   for (i = 0; i < var->cnsts_number; i++)
 256     if (var->cnsts[i].constraint == cnst)
 257       break;
 258
 259   if (i < var->cnsts_number) {
 260     var->cnsts[i].value = value;
 261     sys->modified = 1;
 262   } else
 263     DIE_IMPOSSIBLE;
 264 }
 265
 266 lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 267                                        lmm_variable_t var, int num)
 268 {
 269   if (num < var->cnsts_number)
 270     return (var->cnsts[num].constraint);
 271   else
 272     return NULL;
 273 }
 274
 275 int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var)
 276 {
 277   return (var->cnsts_number);
 278 }
 279
 280 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 281                                      lmm_constraint_t cnst,
 282                                      lmm_element_t * elem)
 283 {
 284   if (!(*elem))
 285     *elem = xbt_swag_getFirst(&(cnst->element_set));
 286   else
 287     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 288   if(*elem)
 289     return (*elem)->variable;
 290   else
 291     return NULL;
 292 }
 293
 294 void *lmm_constraint_id(lmm_constraint_t cnst)
 295 {
 296   return cnst->id;
 297 }
 298
 299 void *lmm_variable_id(lmm_variable_t var)
 300 {
 301   return var->id;
 302 }
 303
 304 static void saturated_constraint_set_update(lmm_system_t sys,
 305                                             lmm_constraint_t cnst,
 306                                             double *min_usage)
 307 {
 308   lmm_constraint_t useless_cnst = NULL;
 309
 310   XBT_IN3("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 311   if (cnst->usage <= 0) {
 312     XBT_OUT;
 313     return;
 314   }
 315   if (cnst->remaining <= 0) {
 316     XBT_OUT;
 317     return;
 318   }
 319   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 320     *min_usage = cnst->remaining / cnst->usage;
 321     LOG3(xbt_log_priority_trace,
 322          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 323          cnst->remaining, cnst->usage);
 324     while ((useless_cnst =
 325             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 326       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 327
 328     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 329   } else if (*min_usage == cnst->remaining / cnst->usage) {
 330     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 331   }
 332   XBT_OUT;
 333 }
 334
 335 static void saturated_variable_set_update(lmm_system_t sys)
 336 {
 337   lmm_constraint_t cnst = NULL;
 338   xbt_swag_t cnst_list = NULL;
 339   lmm_element_t elem = NULL;
 340   xbt_swag_t elem_list = NULL;
 341
 342   cnst_list = &(sys->saturated_constraint_set);
 343   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 344     elem_list = &(cnst->active_element_set);
 345     xbt_swag_foreach(elem, elem_list) {
 346       if (elem->variable->weight <= 0)
 347         break;
 348       if ((elem->value > 0))
 349         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 350     }
 351     xbt_swag_remove(cnst, cnst_list);
 352   }
 353 }
 354
 355 void lmm_print(lmm_system_t sys)
 356 {
 357   lmm_constraint_t cnst = NULL;
 358   lmm_element_t elem = NULL;
 359   lmm_variable_t var = NULL;
 360   xbt_swag_t cnst_list = NULL;
 361   xbt_swag_t var_list = NULL;
 362   xbt_swag_t elem_list = NULL;
 363   char print_buf[1024];
 364   char *trace_buf = xbt_malloc0(sizeof(char));
 365   double sum = 0.0;
 366
 367   /* Printing Objective */
 368   var_list = &(sys->variable_set);
 369   sprintf(print_buf, "MAX-MIN ( ");
 370   trace_buf =
 371       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 372   strcat(trace_buf, print_buf);
 373   xbt_swag_foreach(var, var_list) {
 374     sprintf(print_buf, "'%p'(%f) ", var, var->weight);
 375     trace_buf =
 376         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 377     strcat(trace_buf, print_buf);
 378   }
 379   sprintf(print_buf, ")");
 380   trace_buf =
 381       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 382   strcat(trace_buf, print_buf);
 383   DEBUG1("%s", trace_buf);
 384   trace_buf[0] = '\000';
 385
 386   DEBUG0("Constraints");
 387   /* Printing Constraints */
 388   cnst_list = &(sys->active_constraint_set);
 389   xbt_swag_foreach(cnst, cnst_list) {
 390     sum = 0.0;
 391     elem_list = &(cnst->element_set);
 392     sprintf(print_buf, "\t");
 393     trace_buf =
 394         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 395     strcat(trace_buf, print_buf);
 396     xbt_swag_foreach(elem, elem_list) {
 397       sprintf(print_buf, "%f.'%p'(%f) + ", elem->value,
 398               elem->variable, elem->variable->value);
 399       trace_buf =
 400           xbt_realloc(trace_buf,
 401                       strlen(trace_buf) + strlen(print_buf) + 1);
 402       strcat(trace_buf, print_buf);
 403       sum += elem->value * elem->variable->value;
 404     }
 405     sprintf(print_buf, "0 <= %f ('%p')", cnst->bound, cnst);
 406     trace_buf =
 407         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 408     strcat(trace_buf, print_buf);
 409
 410     if (!cnst->shared) {
 411       sprintf(print_buf, " [MAX-Constraint]");
 412       trace_buf =
 413           xbt_realloc(trace_buf,
 414                       strlen(trace_buf) + strlen(print_buf) + 1);
 415       strcat(trace_buf, print_buf);
 416     }
 417     DEBUG1("%s", trace_buf);
 418     trace_buf[0] = '\000';
 419     if (double_positive(sum - cnst->bound))
 420       WARN3("Incorrect value (%f is not smaller than %f): %g",
 421             sum, cnst->bound, sum - cnst->bound);
 422   }
 423
 424   DEBUG0("Variables");
 425   /* Printing Result */
 426   xbt_swag_foreach(var, var_list) {
 427     if (var->bound > 0) {
 428       DEBUG4("'%p'(%f) : %f (<=%f)", var, var->weight, var->value,
 429              var->bound);
 430       if (double_positive(var->value - var->bound))
 431         WARN2("Incorrect value (%f is not smaller than %f",
 432               var->value, var->bound);
 433     } else
 434       DEBUG3("'%p'(%f) : %f", var, var->weight, var->value);
 435   }
 436
 437   free(trace_buf);
 438 }
 439
 440 void lmm_solve(lmm_system_t sys)
 441 {
 442   lmm_variable_t var = NULL;
 443   lmm_constraint_t cnst = NULL;
 444   lmm_element_t elem = NULL;
 445   xbt_swag_t cnst_list = NULL;
 446   xbt_swag_t var_list = NULL;
 447   xbt_swag_t elem_list = NULL;
 448   double min_usage = -1;
 449
 450   if (!(sys->modified))
 451     return;
 452
 453   /* Init */
 454   var_list = &(sys->variable_set);
 455   DEBUG1("Variable set : %d", xbt_swag_size(var_list));
 456   xbt_swag_foreach(var, var_list) {
 457     int nb=0;
 458     int i;
 459     if(var->weight<=0.0) break;
 460     var->value = 0.0;
 461     for (i = 0; i < var->cnsts_number; i++) {
 462       if(var->cnsts[i].value==0.0) nb++;
 463     }
 464     if((nb==var->cnsts_number) && (var->weight>0.0))
 465       var->value = 1.0;
 466   }
 467
 468   /*
 469    * Compute Usage and store the variables that reach the maximum.
 470    */
 471   cnst_list = &(sys->active_constraint_set);
 472   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 473   xbt_swag_foreach(cnst, cnst_list) {
 474     /* INIT */
 475     cnst->remaining = cnst->bound;
 476     cnst->usage = 0;
 477     elem_list = &(cnst->element_set);
 478     cnst->usage = 0.0;
 479     xbt_swag_foreach(elem, elem_list) {
 480       if (elem->variable->weight <= 0)
 481         break;
 482       if ((elem->value > 0)) {
 483         if (cnst->shared)
 484           cnst->usage += elem->value / elem->variable->weight;
 485         else if (cnst->usage < elem->value / elem->variable->weight)
 486           cnst->usage = elem->value / elem->variable->weight;
 487         DEBUG2("Constraint Usage %p : %f", cnst, cnst->usage);
 488         make_elem_active(elem);
 489       }
 490     }
 491     /* Saturated constraints update */
 492     saturated_constraint_set_update(sys, cnst, &min_usage);
 493   }
 494   saturated_variable_set_update(sys);
 495
 496   /* Saturated variables update */
 497
 498   do {
 499     /* Fix the variables that have to be */
 500     var_list = &(sys->saturated_variable_set);
 501
 502     xbt_swag_foreach(var, var_list) {
 503       if(var->weight<=0.0) DIE_IMPOSSIBLE;
 504       /* First check if some of these variables have reach their upper
 505          bound and update min_usage accordingly. */
 506       DEBUG5
 507           ("var=%p, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 508            var, var->bound, var->weight, min_usage,
 509            var->bound * var->weight);
 510       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 511         min_usage = var->bound * var->weight;
 512         DEBUG1("Updated min_usage=%f", min_usage);
 513       }
 514     }
 515
 516
 517     while ((var = xbt_swag_getFirst(var_list))) {
 518       int i;
 519
 520       var->value = min_usage / var->weight;
 521       DEBUG5("Min usage: %f, Var(%p)->weight: %f, Var(%p)->value: %f ",
 522              min_usage, var, var->weight, var, var->value);
 523
 524
 525       /* Update usage */
 526
 527       for (i = 0; i < var->cnsts_number; i++) {
 528         elem = &var->cnsts[i];
 529         cnst = elem->constraint;
 530         if (cnst->shared) {
 531           double_update(&(cnst->remaining), elem->value * var->value);
 532           double_update(&(cnst->usage), elem->value / var->weight);
 533           make_elem_inactive(elem);
 534         } else {                /* FIXME one day: We recompute usage.... :( */
 535           cnst->usage = 0.0;
 536           make_elem_inactive(elem);
 537           xbt_swag_foreach(elem, elem_list) {
 538             if (elem->variable->weight <= 0)
 539               break;
 540             if (elem->variable->value > 0)
 541               break;
 542             if ((elem->value > 0)) {
 543               if (cnst->usage < elem->value / elem->variable->weight)
 544                 cnst->usage = elem->value / elem->variable->weight;
 545               DEBUG2("Constraint Usage %p : %f", cnst, cnst->usage);
 546               make_elem_active(elem);
 547             }
 548           }
 549         }
 550       }
 551       xbt_swag_remove(var, var_list);
 552     }
 553
 554     /* Find out which variables reach the maximum */
 555     cnst_list = &(sys->active_constraint_set);
 556     min_usage = -1;
 557     xbt_swag_foreach(cnst, cnst_list) {
 558       saturated_constraint_set_update(sys, cnst, &min_usage);
 559     }
 560     saturated_variable_set_update(sys);
 561
 562   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 563
 564   sys->modified = 0;
 565   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 566     lmm_print(sys);
 567   }
 568 }
 569
 570 /* Not a O(1) function */
 571
 572 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 573                 lmm_variable_t var, double value)
 574 {
 575   int i;
 576
 577   sys->modified = 1;
 578   for (i = 0; i < var->cnsts_number; i++)
 579     if (var->cnsts[i].constraint == cnst) {
 580       var->cnsts[i].value = value;
 581       return;
 582     }
 583 }
 584
 585 /** \brief Attribute the value bound to var->bound.
 586  *
 587  *  \param sys the lmm_system_t
 588  *  \param var the lmm_variable_t
 589  *  \param bound the new bound to associate with var
 590  *
 591  *  Makes var->bound equal to bound. Whenever this function is called
 592  *  a change is  signed in the system. To
 593  *  avoid false system changing detection it is a good idea to test
 594  *  (bound != 0) before calling it.
 595  *
 596  */
 597 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 598                                double bound)
 599 {
 600   sys->modified = 1;
 601   var->bound = bound;
 602 }
 603
 604 /** \brief Add the value delta to var->df (the sum of latencies).
 605  *
 606  *  \param sys the lmm_system_t associated
 607  *  \param var the lmm_variable_t which need to updated
 608  *  \param delta the variation of the latency
 609  *
 610  *  Add the value delta to var->df (the sum of latencys associated to the
 611  *  flow). Whenever this function is called a change is  signed in the system. To
 612  *  avoid false system changing detection it is a good idea to test
 613  *  (delta != 0) before calling it.
 614  *
 615  */
 616 void lmm_update_variable_latency(lmm_system_t sys, lmm_variable_t var,
 617                                  double delta)
 618 {
 619   sys->modified = 1;
 620   var->df += delta;
 621 }
 622
 623 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 624                                 double weight)
 625 {
 626   int i;
 627   lmm_element_t elem;
 628
 629   if(weight==var->weight) return;
 630   XBT_IN3("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 631   sys->modified = 1;
 632   var->weight = weight;
 633   xbt_swag_remove(var, &(sys->variable_set));
 634   if (weight)
 635     xbt_swag_insert_at_head(var, &(sys->variable_set));
 636   else
 637     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 638
 639   for (i = 0; i < var->cnsts_number; i++) {
 640     elem = &var->cnsts[i];
 641     xbt_swag_remove(elem, &(elem->constraint->element_set));
 642     if (weight)
 643       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 644     else
 645       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 646   }
 647   if(!weight)
 648     var->value = 0.0;
 649
 650   XBT_OUT;
 651 }
 652
 653 double lmm_get_variable_weight(lmm_variable_t var)
 654 {
 655   return var->weight;
 656 }
 657
 658 void lmm_update_constraint_bound(lmm_system_t sys, lmm_constraint_t cnst,
 659                                  double bound)
 660 {
 661   sys->modified = 1;
 662   cnst->bound = bound;
 663 }
 664
 665 int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 666 {
 667   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 668 }
 669
 670 lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
 671 {
 672   return xbt_swag_getFirst(&(sys->active_constraint_set));
 673 }
 674
 675 lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
 676                                                 lmm_constraint_t cnst)
 677 {
 678   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 679 }