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   DEBUG1("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(64,
  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     WARN2
  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_IN2("(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   free(var->cnsts);
 113   xbt_mallocator_release(sys->variable_mallocator, var);
 114 }
 115
 116 static XBT_INLINE void lmm_cnst_free(lmm_system_t sys,
 117                                      lmm_constraint_t cnst)
 118 {
 119 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
 120 /*            "This list should be empty!"); */
 121   remove_active_constraint(sys, cnst);
 122   free(cnst);
 123 }
 124
 125 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 126                                     double bound_value)
 127 {
 128   lmm_constraint_t cnst = NULL;
 129   s_lmm_element_t elem;
 130
 131   cnst = xbt_new0(s_lmm_constraint_t, 1);
 132   cnst->id = id;
 133   cnst->id_int = Global_const_debug_id++;
 134   xbt_swag_init(&(cnst->element_set),
 135                 xbt_swag_offset(elem, element_set_hookup));
 136   xbt_swag_init(&(cnst->active_element_set),
 137                 xbt_swag_offset(elem, active_element_set_hookup));
 138
 139   cnst->bound = bound_value;
 140   cnst->usage = 0;
 141   cnst->shared = 1;
 142   insert_constraint(sys, cnst);
 143
 144   return cnst;
 145 }
 146
 147 XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
 148 {
 149   cnst->shared = 0;
 150 }
 151
 152 XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
 153 {
 154   return (cnst->shared);
 155 }
 156
 157 XBT_INLINE void lmm_constraint_free(lmm_system_t sys,
 158                                     lmm_constraint_t cnst)
 159 {
 160   remove_constraint(sys, cnst);
 161   lmm_cnst_free(sys, cnst);
 162 }
 163
 164 static void *lmm_variable_mallocator_new_f(void)
 165 {
 166   return xbt_new(s_lmm_variable_t, 1);
 167 }
 168
 169 static void lmm_variable_mallocator_free_f(void *var)
 170 {
 171   xbt_free(var);
 172 }
 173
 174 static void lmm_variable_mallocator_reset_f(void *var)
 175 {
 176   /* memset to zero like calloc */
 177   memset(var, 0, sizeof(s_lmm_variable_t));
 178 }
 179
 180 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 181                                 double weight,
 182                                 double bound, int number_of_constraints)
 183 {
 184   lmm_variable_t var = NULL;
 185   int i;
 186
 187   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 188           sys, id, weight, bound, number_of_constraints);
 189
 190   var = xbt_mallocator_get(sys->variable_mallocator);
 191   var->id = id;
 192   var->id_int = Global_debug_id++;
 193   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
 194   for (i = 0; i < number_of_constraints; i++) {
 195     /* Should be useless because of the
 196        calloc but it seems to help valgrind... */
 197     var->cnsts[i].element_set_hookup.next = NULL;
 198     var->cnsts[i].element_set_hookup.prev = NULL;
 199     var->cnsts[i].active_element_set_hookup.next = NULL;
 200     var->cnsts[i].active_element_set_hookup.prev = NULL;
 201     var->cnsts[i].constraint = NULL;
 202     var->cnsts[i].variable = NULL;
 203     var->cnsts[i].value = 0.0;
 204   }
 205   var->cnsts_size = number_of_constraints;
 206   var->cnsts_number = 0;        /* Should be useless because of the
 207                                    calloc but it seems to help valgrind... */
 208   var->weight = weight;
 209   var->bound = bound;
 210   var->value = 0.0;
 211
 212
 213   var->func_f = func_f_def;
 214   var->func_fp = func_fp_def;
 215   var->func_fpi = func_fpi_def;
 216
 217   if (weight)
 218     xbt_swag_insert_at_head(var, &(sys->variable_set));
 219   else
 220     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 221   XBT_OUT;
 222   return var;
 223 }
 224
 225 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 226 {
 227   remove_variable(sys, var);
 228   lmm_var_free(sys, var);
 229 }
 230
 231 XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 232 {
 233   return (var->value);
 234 }
 235
 236 XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
 237 {
 238   return (var->bound);
 239 }
 240
 241 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 242                 lmm_variable_t var, double value)
 243 {
 244   lmm_element_t elem = NULL;
 245
 246   sys->modified = 1;
 247
 248   xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 249
 250   elem = &(var->cnsts[var->cnsts_number++]);
 251
 252   elem->value = value;
 253   elem->constraint = cnst;
 254   elem->variable = var;
 255
 256   if (var->weight)
 257     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 258   else
 259     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 260
 261   make_constraint_active(sys, cnst);
 262   lmm_update_modified_set(sys, cnst);
 263 }
 264
 265 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 266                     lmm_variable_t var, double value)
 267 {
 268   int i;
 269   sys->modified = 1;
 270
 271   for (i = 0; i < var->cnsts_number; i++)
 272     if (var->cnsts[i].constraint == cnst)
 273       break;
 274
 275   if (i < var->cnsts_number) {
 276     if (cnst->shared)
 277       var->cnsts[i].value += value;
 278     else
 279       var->cnsts[i].value = MAX(var->cnsts[i].value, value);
 280     lmm_update_modified_set(sys, cnst);
 281   } else
 282     lmm_expand(sys, cnst, var, value);
 283 }
 284
 285 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 286                         lmm_variable_t var, double value)
 287 {
 288   int i;
 289
 290   for (i = 0; i < var->cnsts_number; i++)
 291     if (var->cnsts[i].constraint == cnst)
 292       break;
 293
 294   if (i < var->cnsts_number) {
 295     var->cnsts[i].value = value;
 296     sys->modified = 1;
 297     lmm_update_modified_set(sys, cnst);
 298   } else
 299     DIE_IMPOSSIBLE;
 300 }
 301
 302 XBT_INLINE lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 303                                                   lmm_variable_t var,
 304                                                   int num)
 305 {
 306   if (num < var->cnsts_number)
 307     return (var->cnsts[num].constraint);
 308   else
 309     return NULL;
 310 }
 311
 312 XBT_INLINE int lmm_get_number_of_cnst_from_var(lmm_system_t sys,
 313                                                lmm_variable_t var)
 314 {
 315   return (var->cnsts_number);
 316 }
 317
 318 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 319                                      lmm_constraint_t cnst,
 320                                      lmm_element_t * elem)
 321 {
 322   if (!(*elem))
 323     *elem = xbt_swag_getFirst(&(cnst->element_set));
 324   else
 325     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 326   if (*elem)
 327     return (*elem)->variable;
 328   else
 329     return NULL;
 330 }
 331
 332 XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 333 {
 334   return cnst->id;
 335 }
 336
 337 XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 338 {
 339   return var->id;
 340 }
 341
 342 static XBT_INLINE void saturated_constraint_set_update(lmm_system_t sys,
 343                                                        lmm_constraint_t
 344                                                        cnst,
 345                                                        double *min_usage)
 346 {
 347   lmm_constraint_t useless_cnst = NULL;
 348
 349   XBT_IN3("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 350   if (cnst->usage <= 0) {
 351     XBT_OUT;
 352     return;
 353   }
 354   if (cnst->remaining <= 0) {
 355     XBT_OUT;
 356     return;
 357   }
 358   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 359     *min_usage = cnst->remaining / cnst->usage;
 360     LOG3(xbt_log_priority_trace,
 361          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 362          cnst->remaining, cnst->usage);
 363     while ((useless_cnst =
 364             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 365       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 366
 367     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 368   } else if (*min_usage == cnst->remaining / cnst->usage) {
 369     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 370   }
 371   XBT_OUT;
 372 }
 373
 374 static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 375 {
 376   lmm_constraint_t cnst = NULL;
 377   xbt_swag_t cnst_list = NULL;
 378   lmm_element_t elem = NULL;
 379   xbt_swag_t elem_list = NULL;
 380
 381   cnst_list = &(sys->saturated_constraint_set);
 382   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 383     elem_list = &(cnst->active_element_set);
 384     xbt_swag_foreach(elem, elem_list) {
 385       if (elem->variable->weight <= 0)
 386         break;
 387       if ((elem->value > 0))
 388         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 389     }
 390     xbt_swag_remove(cnst, cnst_list);
 391   }
 392 }
 393
 394 void lmm_print(lmm_system_t sys)
 395 {
 396   lmm_constraint_t cnst = NULL;
 397   lmm_element_t elem = NULL;
 398   lmm_variable_t var = NULL;
 399   xbt_swag_t cnst_list = NULL;
 400   xbt_swag_t var_list = NULL;
 401   xbt_swag_t elem_list = NULL;
 402   char print_buf[1024];
 403   char *trace_buf = xbt_malloc0(sizeof(char));
 404   double sum = 0.0;
 405
 406   /* Printing Objective */
 407   var_list = &(sys->variable_set);
 408   sprintf(print_buf, "MAX-MIN ( ");
 409   trace_buf =
 410       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 411   strcat(trace_buf, print_buf);
 412   xbt_swag_foreach(var, var_list) {
 413     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 414     trace_buf =
 415         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 416     strcat(trace_buf, print_buf);
 417   }
 418   sprintf(print_buf, ")");
 419   trace_buf =
 420       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 421   strcat(trace_buf, print_buf);
 422   fprintf(stderr, "%s", trace_buf);
 423   //DEBUG1("%20s", trace_buf); FIXME
 424   trace_buf[0] = '\000';
 425
 426   DEBUG0("Constraints");
 427   /* Printing Constraints */
 428   cnst_list = &(sys->active_constraint_set);
 429   xbt_swag_foreach(cnst, cnst_list) {
 430     sum = 0.0;
 431     elem_list = &(cnst->element_set);
 432     sprintf(print_buf, "\t");
 433     trace_buf =
 434         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 435     strcat(trace_buf, print_buf);
 436     sprintf(print_buf, "%s(",(cnst->shared)?"":"max");
 437     trace_buf =
 438       xbt_realloc(trace_buf,
 439                   strlen(trace_buf) + strlen(print_buf) + 1);
 440     strcat(trace_buf, print_buf);
 441     xbt_swag_foreach(elem, elem_list) {
 442       sprintf(print_buf, "%f.'%d'(%f) %s ", elem->value,
 443               elem->variable->id_int, elem->variable->value,(cnst->shared)?"+":",");
 444       trace_buf =
 445           xbt_realloc(trace_buf,
 446                       strlen(trace_buf) + strlen(print_buf) + 1);
 447       strcat(trace_buf, print_buf);
 448       if(cnst->shared)
 449         sum += elem->value * elem->variable->value;
 450       else
 451         sum = MAX(sum,elem->value * elem->variable->value);
 452     }
 453     sprintf(print_buf, "0) <= %f ('%d')", cnst->bound, cnst->id_int);
 454     trace_buf =
 455         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 456     strcat(trace_buf, print_buf);
 457
 458     if (!cnst->shared) {
 459       sprintf(print_buf, " [MAX-Constraint]");
 460       trace_buf =
 461           xbt_realloc(trace_buf,
 462                       strlen(trace_buf) + strlen(print_buf) + 1);
 463       strcat(trace_buf, print_buf);
 464     }
 465     //   DEBUG1("%s", trace_buf);
 466     fprintf(stderr, "%s\n", trace_buf);
 467     trace_buf[0] = '\000';
 468     xbt_assert3(!double_positive(sum - cnst->bound),
 469                 "Incorrect value (%f is not smaller than %f): %g",
 470                 sum, cnst->bound, sum - cnst->bound);
 471   }
 472
 473   DEBUG0("Variables");
 474   /* Printing Result */
 475   xbt_swag_foreach(var, var_list) {
 476     if (var->bound > 0) {
 477       DEBUG4("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 478              var->bound);
 479       xbt_assert2(!double_positive(var->value - var->bound),
 480                   "Incorrect value (%f is not smaller than %f",
 481                   var->value, var->bound);
 482     } else {
 483       DEBUG3("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 484     }
 485   }
 486
 487   free(trace_buf);
 488 }
 489
 490 void lmm_solve(lmm_system_t sys)
 491 {
 492   lmm_variable_t var = NULL;
 493   lmm_constraint_t cnst = NULL;
 494   lmm_element_t elem = NULL;
 495   xbt_swag_t cnst_list = NULL;
 496   xbt_swag_t var_list = NULL;
 497   xbt_swag_t elem_list = NULL;
 498   double min_usage = -1;
 499   double min_bound = -1;
 500
 501   if (!(sys->modified))
 502     return;
 503
 504   XBT_IN1("(sys=%p)", sys);
 505
 506   /*
 507    * Compute Usage and store the variables that reach the maximum.
 508    */
 509   cnst_list =
 510       sys->
 511       selective_update_active ? &(sys->modified_constraint_set) :
 512       &(sys->active_constraint_set);
 513
 514   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 515   /* Init: Only modified code portions */
 516   xbt_swag_foreach(cnst, cnst_list) {
 517     elem_list = &(cnst->element_set);
 518     //DEBUG1("Variable set : %d", xbt_swag_size(elem_list));
 519     xbt_swag_foreach(elem, elem_list) {
 520       var = elem->variable;
 521       if (var->weight <= 0.0)
 522         break;
 523       var->value = 0.0;
 524     }
 525   }
 526
 527   xbt_swag_foreach(cnst, cnst_list) {
 528     /* INIT */
 529     cnst->remaining = cnst->bound;
 530     if (cnst->remaining == 0)
 531       continue;
 532     cnst->usage = 0;
 533     elem_list = &(cnst->element_set);
 534     xbt_swag_foreach(elem, elem_list) {
 535       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 536       if (elem->variable->weight <= 0)
 537         break;
 538       if ((elem->value > 0)) {
 539         if (cnst->shared)
 540           cnst->usage += elem->value / elem->variable->weight;
 541         else if (cnst->usage < elem->value / elem->variable->weight)
 542           cnst->usage = elem->value / elem->variable->weight;
 543
 544         make_elem_active(elem);
 545         if(keep_track){
 546             xbt_swag_insert((elem->variable)->id, keep_track);
 547         }
 548       }
 549     }
 550     DEBUG2("Constraint Usage '%d' : %f", cnst->id_int, cnst->usage);
 551     /* Saturated constraints update */
 552     saturated_constraint_set_update(sys, cnst, &min_usage);
 553   }
 554   saturated_variable_set_update(sys);
 555
 556   /* Saturated variables update */
 557
 558   do {
 559     /* Fix the variables that have to be */
 560     var_list = &(sys->saturated_variable_set);
 561
 562     xbt_swag_foreach(var, var_list) {
 563       if (var->weight <= 0.0)
 564         DIE_IMPOSSIBLE;
 565       /* First check if some of these variables have reach their upper
 566          bound and update min_usage accordingly. */
 567       DEBUG5
 568           ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 569            var->id_int, var->bound, var->weight, min_usage,
 570            var->bound * var->weight);
 571       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 572         if (min_bound < 0)
 573           min_bound = var->bound;
 574         else
 575           min_bound = MIN(min_bound, var->bound);
 576         DEBUG1("Updated min_bound=%f", min_bound);
 577       }
 578     }
 579
 580
 581     while ((var = xbt_swag_getFirst(var_list))) {
 582       int i;
 583
 584       if (min_bound < 0) {
 585         var->value = min_usage / var->weight;
 586       } else {
 587         if (min_bound == var->bound)
 588           var->value = var->bound;
 589         else {
 590           xbt_swag_remove(var, var_list);
 591           continue;
 592         }
 593       }
 594       DEBUG5("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 595              min_usage, var->id_int, var->weight, var->id_int, var->value);
 596
 597
 598       /* Update usage */
 599
 600       for (i = 0; i < var->cnsts_number; i++) {
 601         elem = &var->cnsts[i];
 602         cnst = elem->constraint;
 603         if (cnst->shared) {
 604           double_update(&(cnst->remaining), elem->value * var->value);
 605           double_update(&(cnst->usage), elem->value / var->weight);
 606           make_elem_inactive(elem);
 607         } else {                /* FIXME one day: We recompute usage.... :( */
 608           cnst->usage = 0.0;
 609           make_elem_inactive(elem);
 610           elem_list = &(cnst->element_set);
 611           xbt_swag_foreach(elem, elem_list) {
 612             if (elem->variable->weight <= 0)
 613               break;
 614             if (elem->variable->value > 0)
 615               break;
 616             if ((elem->value > 0)) {
 617               cnst->usage =
 618                   MAX(cnst->usage, elem->value / elem->variable->weight);
 619               DEBUG2("Constraint Usage %d : %f", cnst->id_int,
 620                      cnst->usage);
 621               make_elem_active(elem);
 622             }
 623           }
 624         }
 625       }
 626       xbt_swag_remove(var, var_list);
 627     }
 628
 629     /* Find out which variables reach the maximum */
 630     cnst_list =
 631         sys->selective_update_active ? &(sys->modified_constraint_set) :
 632         &(sys->active_constraint_set);
 633     min_usage = -1;
 634     min_bound = -1;
 635     xbt_swag_foreach(cnst, cnst_list) {
 636       saturated_constraint_set_update(sys, cnst, &min_usage);
 637     }
 638     saturated_variable_set_update(sys);
 639
 640   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 641
 642   sys->modified = 0;
 643   if (sys->selective_update_active)
 644     lmm_remove_all_modified_set(sys);
 645
 646   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 647     lmm_print(sys);
 648   }
 649   XBT_OUT;
 650 }
 651
 652 /* Not a O(1) function */
 653
 654 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 655                 lmm_variable_t var, double value)
 656 {
 657   int i;
 658
 659   for (i = 0; i < var->cnsts_number; i++)
 660     if (var->cnsts[i].constraint == cnst) {
 661       var->cnsts[i].value = value;
 662       sys->modified = 1;
 663       lmm_update_modified_set(sys, cnst);
 664       return;
 665     }
 666 }
 667
 668 /** \brief Attribute the value bound to var->bound.
 669  *
 670  *  \param sys the lmm_system_t
 671  *  \param var the lmm_variable_t
 672  *  \param bound the new bound to associate with var
 673  *
 674  *  Makes var->bound equal to bound. Whenever this function is called
 675  *  a change is  signed in the system. To
 676  *  avoid false system changing detection it is a good idea to test
 677  *  (bound != 0) before calling it.
 678  *
 679  */
 680 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 681                                double bound)
 682 {
 683   int i;
 684
 685   sys->modified = 1;
 686   var->bound = bound;
 687
 688   for (i = 0; i < var->cnsts_number; i++)
 689     lmm_update_modified_set(sys, var->cnsts[i].constraint);
 690
 691 }
 692
 693
 694 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 695                                 double weight)
 696 {
 697   int i;
 698   lmm_element_t elem;
 699
 700   if (weight == var->weight)
 701     return;
 702   XBT_IN3("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 703   sys->modified = 1;
 704   var->weight = weight;
 705   xbt_swag_remove(var, &(sys->variable_set));
 706   if (weight)
 707     xbt_swag_insert_at_head(var, &(sys->variable_set));
 708   else
 709     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 710
 711   for (i = 0; i < var->cnsts_number; i++) {
 712     elem = &var->cnsts[i];
 713     xbt_swag_remove(elem, &(elem->constraint->element_set));
 714     if (weight)
 715       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 716     else
 717       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 718
 719     lmm_update_modified_set(sys, elem->constraint);
 720   }
 721   if (!weight)
 722     var->value = 0.0;
 723
 724   XBT_OUT;
 725 }
 726
 727 XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 728 {
 729   return var->weight;
 730 }
 731
 732 XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys,
 733                                             lmm_constraint_t cnst,
 734                                             double bound)
 735 {
 736   sys->modified = 1;
 737   lmm_update_modified_set(sys, cnst);
 738   cnst->bound = bound;
 739 }
 740
 741 XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 742 {
 743   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 744 }
 745
 746 XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t
 747                                                             sys)
 748 {
 749   return xbt_swag_getFirst(&(sys->active_constraint_set));
 750 }
 751
 752 XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t
 753                                                            sys,
 754                                                            lmm_constraint_t
 755                                                            cnst)
 756 {
 757   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 758 }
 759
 760 #ifdef HAVE_LATENCY_BOUND_TRACKING
 761 XBT_INLINE int lmm_is_variable_limited_by_latency(lmm_variable_t var)
 762 {
 763   return (double_equals(var->bound, var->value));
 764 }
 765 #endif
 766
 767
 768 /** \brief Update the constraint set propagating recursively to
 769  *  other constraints so the system should not be entirely computed.
 770  *
 771  *  \param sys the lmm_system_t
 772  *  \param cnst the lmm_constraint_t affected by the change
 773  *
 774  *  A recursive algorithm to optimize the system recalculation selecting only
 775  *  constraints that have changed. Each constraint change is propagated
 776  *  to the list of constraints for each variable.
 777  */
 778 static void lmm_update_modified_set(lmm_system_t sys,
 779                                     lmm_constraint_t cnst)
 780 {
 781   lmm_element_t elem = NULL;
 782   lmm_variable_t var = NULL;
 783   xbt_swag_t elem_list = NULL;
 784   int i;
 785
 786   /* return if selective update isn't active */
 787   if (!sys->selective_update_active)
 788     return;
 789
 790   //DEBUG1("Updating modified constraint set with constraint %d", cnst->id_int);
 791
 792   if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
 793     return;
 794
 795   //DEBUG1("Inserting into modified constraint set %d", cnst->id_int);
 796
 797   /* add to modified set */
 798   xbt_swag_insert(cnst, &(sys->modified_constraint_set));
 799
 800   elem_list = &(cnst->element_set);
 801   xbt_swag_foreach(elem, elem_list) {
 802     var = elem->variable;
 803     for (i = 0; i < var->cnsts_number; i++)
 804       if (cnst != var->cnsts[i].constraint) {
 805         //DEBUG2("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
 806         lmm_update_modified_set(sys, var->cnsts[i].constraint);
 807       }
 808   }
 809 }
 810
 811 /** \brief Remove all constraints of the modified_constraint_set.
 812  *
 813  *  \param sys the lmm_system_t
 814  */
 815 static void lmm_remove_all_modified_set(lmm_system_t sys)
 816 {
 817   lmm_element_t elem = NULL;
 818   lmm_element_t elem_next = NULL;
 819   xbt_swag_t elem_list = NULL;
 820
 821   elem_list = &(sys->modified_constraint_set);
 822   xbt_swag_foreach_safe(elem, elem_next, elem_list) {
 823     xbt_swag_remove(elem, elem_list);
 824   }
 825 }