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Warn when there is some remaining actions in the system we're freeing because it...
[simgrid.git] / src / surf / maxmin.c
index 61be934..e0d093b 100644 (file)
 #include "xbt/mallocator.h"
 #include "maxmin_private.h"
 #include <stdlib.h>
-#include <stdio.h> /* sprintf */
+#include <stdio.h>              /* sprintf */
 #include <math.h>
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
-                               "Logging specific to SURF (maxmin)");
+                                "Logging specific to SURF (maxmin)");
 
 static void *lmm_variable_mallocator_new_f(void);
 static void lmm_variable_mallocator_free_f(void *var);
 static void lmm_variable_mallocator_reset_f(void *var);
-
+static void lmm_update_modified_set(lmm_system_t sys, lmm_constraint_t cnst);
+static void lmm_remove_all_modified_set(lmm_system_t sys);
+int sg_maxmin_selective_update = 1;
+static int Global_debug_id = 1;
+static int Global_const_debug_id = 1;
 lmm_system_t lmm_system_new(void)
 {
   lmm_system_t l = NULL;
@@ -29,23 +33,30 @@ lmm_system_t lmm_system_new(void)
   l = xbt_new0(s_lmm_system_t, 1);
 
   l->modified = 0;
+  l->selective_update_active = sg_maxmin_selective_update;
+
+  DEBUG1("Setting selective_update_active flag to %d\n",
+         l->selective_update_active);
+
   xbt_swag_init(&(l->variable_set),
-               xbt_swag_offset(var, variable_set_hookup));
+                xbt_swag_offset(var, variable_set_hookup));
   xbt_swag_init(&(l->constraint_set),
-               xbt_swag_offset(cnst, constraint_set_hookup));
+                xbt_swag_offset(cnst, constraint_set_hookup));
 
   xbt_swag_init(&(l->active_constraint_set),
-               xbt_swag_offset(cnst, active_constraint_set_hookup));
+                xbt_swag_offset(cnst, active_constraint_set_hookup));
 
+  xbt_swag_init(&(l->modified_constraint_set),
+                xbt_swag_offset(cnst, modified_constraint_set_hookup));
   xbt_swag_init(&(l->saturated_variable_set),
-               xbt_swag_offset(var, saturated_variable_set_hookup));
+                xbt_swag_offset(var, saturated_variable_set_hookup));
   xbt_swag_init(&(l->saturated_constraint_set),
-               xbt_swag_offset(cnst, saturated_constraint_set_hookup));
+                xbt_swag_offset(cnst, saturated_constraint_set_hookup));
 
   l->variable_mallocator = xbt_mallocator_new(64,
-                                             lmm_variable_mallocator_new_f,
-                                             lmm_variable_mallocator_free_f,
-                                             lmm_variable_mallocator_reset_f);
+                                              lmm_variable_mallocator_new_f,
+                                              lmm_variable_mallocator_free_f,
+                                              lmm_variable_mallocator_reset_f);
 
   return l;
 }
@@ -55,8 +66,11 @@ void lmm_system_free(lmm_system_t sys)
   lmm_variable_t var = NULL;
   lmm_constraint_t cnst = NULL;
 
-  while ((var = extract_variable(sys)))
+  while ((var = extract_variable(sys))) {
+    WARN2("Variable %p (%d) still in LMM system when freing it: this may be a bug",
+        var,var->id_int);
     lmm_var_free(sys, var);
+  }
 
   while ((cnst = extract_constraint(sys)))
     lmm_cnst_free(sys, cnst);
@@ -65,7 +79,7 @@ void lmm_system_free(lmm_system_t sys)
   free(sys);
 }
 
-void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
+XBT_INLINE void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
 {
   int i;
   lmm_element_t elem = NULL;
@@ -79,6 +93,8 @@ void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
     if (!xbt_swag_size(&(elem->constraint->element_set)))
       make_constraint_inactive(sys, elem->constraint);
+    else
+      lmm_update_modified_set(sys, elem->constraint);
   }
   var->cnsts_number = 0;
   XBT_OUT;
@@ -92,7 +108,7 @@ static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
   xbt_mallocator_release(sys->variable_mallocator, var);
 }
 
-static void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
+static XBT_INLINE void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
 {
 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
 /*           "This list should be empty!"); */
@@ -101,17 +117,18 @@ static void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
 }
 
 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
-                                   double bound_value)
+                                    double bound_value)
 {
   lmm_constraint_t cnst = NULL;
   s_lmm_element_t elem;
 
   cnst = xbt_new0(s_lmm_constraint_t, 1);
   cnst->id = id;
+  cnst->id_int = Global_const_debug_id++;
   xbt_swag_init(&(cnst->element_set),
-               xbt_swag_offset(elem, element_set_hookup));
+                xbt_swag_offset(elem, element_set_hookup));
   xbt_swag_init(&(cnst->active_element_set),
-               xbt_swag_offset(elem, active_element_set_hookup));
+                xbt_swag_offset(elem, active_element_set_hookup));
 
   cnst->bound = bound_value;
   cnst->usage = 0;
@@ -121,17 +138,17 @@ lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
   return cnst;
 }
 
-void lmm_constraint_shared(lmm_constraint_t cnst)
+XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
 {
   cnst->shared = 0;
 }
 
-int lmm_constraint_is_shared(lmm_constraint_t cnst)
+XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
 {
   return (cnst->shared);
 }
 
-void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
+XBT_INLINE void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
 {
   remove_constraint(sys, cnst);
   lmm_cnst_free(sys, cnst);
@@ -154,17 +171,18 @@ static void lmm_variable_mallocator_reset_f(void *var)
 }
 
 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
-                               double weight,
-                               double bound, int number_of_constraints)
+                                double weight,
+                                double bound, int number_of_constraints)
 {
   lmm_variable_t var = NULL;
   int i;
 
   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
-         sys, id, weight, bound, number_of_constraints);
+          sys, id, weight, bound, number_of_constraints);
 
   var = xbt_mallocator_get(sys->variable_mallocator);
   var->id = id;
+  var->id_int = Global_debug_id++;
   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
   for (i = 0; i < number_of_constraints; i++) {
     /* Should be useless because of the 
@@ -178,12 +196,12 @@ lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
     var->cnsts[i].value = 0.0;
   }
   var->cnsts_size = number_of_constraints;
-  var->cnsts_number = 0;       /* Should be useless because of the 
-                                  calloc but it seems to help valgrind... */
+  var->cnsts_number = 0;        /* Should be useless because of the 
+                                   calloc but it seems to help valgrind... */
   var->weight = weight;
   var->bound = bound;
   var->value = 0.0;
-  var->df = 0.0;
+
 
   var->func_f = func_f_def;
   var->func_fp = func_fp_def;
@@ -203,18 +221,18 @@ void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
   lmm_var_free(sys, var);
 }
 
-double lmm_variable_getvalue(lmm_variable_t var)
+XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 {
   return (var->value);
 }
 
-double lmm_variable_getbound(lmm_variable_t var)
+XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
 {
   return (var->bound);
 }
 
 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
-               lmm_variable_t var, double value)
+                lmm_variable_t var, double value)
 {
   lmm_element_t elem = NULL;
 
@@ -234,10 +252,11 @@ void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 
   make_constraint_active(sys, cnst);
+  lmm_update_modified_set(sys, cnst);
 }
 
 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
-                   lmm_variable_t var, double value)
+                    lmm_variable_t var, double value)
 {
   int i;
   sys->modified = 1;
@@ -247,14 +266,17 @@ void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
       break;
 
   if (i < var->cnsts_number) {
-    if(cnst->shared) var->cnsts[i].value += value;
-    else var->cnsts[i].value = MAX(var->cnsts[i].value,value);
-  }  else
+    if (cnst->shared)
+      var->cnsts[i].value += value;
+    else
+      var->cnsts[i].value = MAX(var->cnsts[i].value, value);
+    lmm_update_modified_set(sys, cnst);
+  } else
     lmm_expand(sys, cnst, var, value);
 }
 
 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
-                       lmm_variable_t var, double value)
+                        lmm_variable_t var, double value)
 {
   int i;
 
@@ -265,12 +287,13 @@ void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
   if (i < var->cnsts_number) {
     var->cnsts[i].value = value;
     sys->modified = 1;
+    lmm_update_modified_set(sys, cnst);
   } else
     DIE_IMPOSSIBLE;
 }
 
-lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
-                                      lmm_variable_t var, int num)
+XBT_INLINE lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
+                                       lmm_variable_t var, int num)
 {
   if (num < var->cnsts_number)
     return (var->cnsts[num].constraint);
@@ -278,38 +301,38 @@ lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
     return NULL;
 }
 
-int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var)
+XBT_INLINE int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var)
 {
   return (var->cnsts_number);
 }
 
 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
-                                    lmm_constraint_t cnst,
-                                    lmm_element_t * elem)
+                                     lmm_constraint_t cnst,
+                                     lmm_element_t * elem)
 {
   if (!(*elem))
     *elem = xbt_swag_getFirst(&(cnst->element_set));
   else
     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
-  if(*elem)
+  if (*elem)
     return (*elem)->variable;
-  else 
+  else
     return NULL;
 }
 
-void *lmm_constraint_id(lmm_constraint_t cnst)
+XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 {
   return cnst->id;
 }
 
-void *lmm_variable_id(lmm_variable_t var)
+XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 {
   return var->id;
 }
 
-static void saturated_constraint_set_update(lmm_system_t sys,
-                                           lmm_constraint_t cnst,
-                                           double *min_usage)
+static XBT_INLINE void saturated_constraint_set_update(lmm_system_t sys,
+                                            lmm_constraint_t cnst,
+                                            double *min_usage)
 {
   lmm_constraint_t useless_cnst = NULL;
 
@@ -325,10 +348,10 @@ static void saturated_constraint_set_update(lmm_system_t sys,
   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
     *min_usage = cnst->remaining / cnst->usage;
     LOG3(xbt_log_priority_trace,
-        "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
-        cnst->remaining, cnst->usage);
+         "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
+         cnst->remaining, cnst->usage);
     while ((useless_cnst =
-           xbt_swag_getFirst(&(sys->saturated_constraint_set))))
+            xbt_swag_getFirst(&(sys->saturated_constraint_set))))
       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 
     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
@@ -338,7 +361,7 @@ static void saturated_constraint_set_update(lmm_system_t sys,
   XBT_OUT;
 }
 
-static void saturated_variable_set_update(lmm_system_t sys)
+static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 {
   lmm_constraint_t cnst = NULL;
   xbt_swag_t cnst_list = NULL;
@@ -350,9 +373,9 @@ static void saturated_variable_set_update(lmm_system_t sys)
     elem_list = &(cnst->active_element_set);
     xbt_swag_foreach(elem, elem_list) {
       if (elem->variable->weight <= 0)
-       break;
+        break;
       if ((elem->value > 0))
-       xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
+        xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
     }
     xbt_swag_remove(cnst, cnst_list);
   }
@@ -374,19 +397,20 @@ void lmm_print(lmm_system_t sys)
   var_list = &(sys->variable_set);
   sprintf(print_buf, "MAX-MIN ( ");
   trace_buf =
-      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+    xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
   strcat(trace_buf, print_buf);
   xbt_swag_foreach(var, var_list) {
-    sprintf(print_buf, "'%p'(%f) ", var, var->weight);
+    sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
     trace_buf =
-       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
     strcat(trace_buf, print_buf);
   }
   sprintf(print_buf, ")");
   trace_buf =
-      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+    xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
   strcat(trace_buf, print_buf);
-  DEBUG1("%s", trace_buf);
+  fprintf(stderr, "%s", trace_buf);
+  //DEBUG1("%20s", trace_buf); FIXME
   trace_buf[0] = '\000';
 
   DEBUG0("Constraints");
@@ -397,47 +421,47 @@ void lmm_print(lmm_system_t sys)
     elem_list = &(cnst->element_set);
     sprintf(print_buf, "\t");
     trace_buf =
-       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
     strcat(trace_buf, print_buf);
     xbt_swag_foreach(elem, elem_list) {
-      sprintf(print_buf, "%f.'%p'(%f) + ", elem->value,
-             elem->variable, elem->variable->value);
+      sprintf(print_buf, "%f.'%d'(%f) + ", elem->value,
+              elem->variable->id_int, elem->variable->value);
       trace_buf =
-         xbt_realloc(trace_buf,
-                     strlen(trace_buf) + strlen(print_buf) + 1);
+        xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
       strcat(trace_buf, print_buf);
       sum += elem->value * elem->variable->value;
     }
-    sprintf(print_buf, "0 <= %f ('%p')", cnst->bound, cnst);
+    sprintf(print_buf, "0 <= %f ('%d')", cnst->bound, cnst->id_int);
     trace_buf =
-       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
     strcat(trace_buf, print_buf);
 
     if (!cnst->shared) {
       sprintf(print_buf, " [MAX-Constraint]");
       trace_buf =
-         xbt_realloc(trace_buf,
-                     strlen(trace_buf) + strlen(print_buf) + 1);
+        xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
       strcat(trace_buf, print_buf);
     }
-    DEBUG1("%s", trace_buf);
+    //   DEBUG1("%s", trace_buf);
+    fprintf(stderr, "%s", trace_buf);
     trace_buf[0] = '\000';
-    if (double_positive(sum - cnst->bound))
-      WARN3("Incorrect value (%f is not smaller than %f): %g",
-           sum, cnst->bound, sum - cnst->bound);
+    xbt_assert3(!double_positive(sum - cnst->bound),
+                "Incorrect value (%f is not smaller than %f): %g",
+                sum, cnst->bound, sum - cnst->bound);
   }
 
   DEBUG0("Variables");
   /* Printing Result */
   xbt_swag_foreach(var, var_list) {
     if (var->bound > 0) {
-      DEBUG4("'%p'(%f) : %f (<=%f)", var, var->weight, var->value,
-            var->bound);
-      if (double_positive(var->value - var->bound))
-       WARN2("Incorrect value (%f is not smaller than %f",
-             var->value, var->bound);
-    } else
-      DEBUG3("'%p'(%f) : %f", var, var->weight, var->value);
+      DEBUG4("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
+             var->bound);
+      xbt_assert2(!double_positive(var->value - var->bound),
+                  "Incorrect value (%f is not smaller than %f",
+                  var->value, var->bound);
+    } else {
+      DEBUG3("'%d'(%f) : %f", var->id_int, var->weight, var->value);
+    }
   }
 
   free(trace_buf);
@@ -452,48 +476,52 @@ void lmm_solve(lmm_system_t sys)
   xbt_swag_t var_list = NULL;
   xbt_swag_t elem_list = NULL;
   double min_usage = -1;
+  double min_bound = -1;
 
   if (!(sys->modified))
     return;
 
-  /* Init */
-  var_list = &(sys->variable_set);
-  DEBUG1("Variable set : %d", xbt_swag_size(var_list));
-  xbt_swag_foreach(var, var_list) {
-    int nb=0;
-    int i;
-    if(var->weight<=0.0) break;
-    var->value = 0.0;
-    for (i = 0; i < var->cnsts_number; i++) {
-      if(var->cnsts[i].value==0.0) nb++;
+  /*
+   * Compute Usage and store the variables that reach the maximum.
+   */
+  cnst_list = sys->selective_update_active ? &(sys->modified_constraint_set) :
+    &(sys->active_constraint_set);
+
+  DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
+  /* Init: Only modified code portions */
+  xbt_swag_foreach(cnst, cnst_list) {
+    elem_list = &(cnst->element_set);
+    //DEBUG1("Variable set : %d", xbt_swag_size(elem_list));
+    xbt_swag_foreach(elem, elem_list) {
+      var = elem->variable;
+      if (var->weight <= 0.0)
+        break;
+      var->value = 0.0;
     }
-    if((nb==var->cnsts_number) && (var->weight>0.0))
-      var->value = 1.0;
   }
 
-  /* 
-   * Compute Usage and store the variables that reach the maximum.
-   */
-  cnst_list = &(sys->active_constraint_set);
   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
   xbt_swag_foreach(cnst, cnst_list) {
     /* INIT */
     cnst->remaining = cnst->bound;
+    if (cnst->remaining == 0)
+      continue;
     cnst->usage = 0;
     elem_list = &(cnst->element_set);
-    cnst->usage = 0.0;
     xbt_swag_foreach(elem, elem_list) {
+      /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
       if (elem->variable->weight <= 0)
-       break;
+        break;
       if ((elem->value > 0)) {
-       if (cnst->shared)
-         cnst->usage += elem->value / elem->variable->weight;
-       else if (cnst->usage < elem->value / elem->variable->weight)
-         cnst->usage = elem->value / elem->variable->weight;
-       DEBUG2("Constraint Usage %p : %f", cnst, cnst->usage);
-       make_elem_active(elem);
+        if (cnst->shared)
+          cnst->usage += elem->value / elem->variable->weight;
+        else if (cnst->usage < elem->value / elem->variable->weight)
+          cnst->usage = elem->value / elem->variable->weight;
+
+        make_elem_active(elem);
       }
     }
+    DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
     /* Saturated constraints update */
     saturated_constraint_set_update(sys, cnst, &min_usage);
   }
@@ -506,16 +534,20 @@ void lmm_solve(lmm_system_t sys)
     var_list = &(sys->saturated_variable_set);
 
     xbt_swag_foreach(var, var_list) {
-      if(var->weight<=0.0) DIE_IMPOSSIBLE;
+      if (var->weight <= 0.0)
+        DIE_IMPOSSIBLE;
       /* First check if some of these variables have reach their upper
          bound and update min_usage accordingly. */
       DEBUG5
-         ("var=%p, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
-          var, var->bound, var->weight, min_usage,
-          var->bound * var->weight);
+        ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
+         var->id_int, var->bound, var->weight, min_usage,
+         var->bound * var->weight);
       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
-       min_usage = var->bound * var->weight;
-       DEBUG1("Updated min_usage=%f", min_usage);
+        if (min_bound < 0)
+          min_bound = var->bound;
+        else
+          min_bound = MIN(min_bound, var->bound);
+        DEBUG1("Updated min_bound=%f", min_bound);
       }
     }
 
@@ -523,43 +555,55 @@ void lmm_solve(lmm_system_t sys)
     while ((var = xbt_swag_getFirst(var_list))) {
       int i;
 
-      var->value = min_usage / var->weight;
-      DEBUG5("Min usage: %f, Var(%p)->weight: %f, Var(%p)->value: %f ",
-            min_usage, var, var->weight, var, var->value);
+      if (min_bound < 0) {
+        var->value = min_usage / var->weight;
+      } else {
+        if (min_bound == var->bound)
+          var->value = var->bound;
+        else {
+          xbt_swag_remove(var, var_list);
+          continue;
+        }
+      }
+      DEBUG5("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
+             min_usage, var->id_int, var->weight, var->id_int, var->value);
 
 
       /* Update usage */
 
       for (i = 0; i < var->cnsts_number; i++) {
-       elem = &var->cnsts[i];
-       cnst = elem->constraint;
-       if (cnst->shared) {
-         double_update(&(cnst->remaining), elem->value * var->value);
-         double_update(&(cnst->usage), elem->value / var->weight);
-         make_elem_inactive(elem);
-       } else {                /* FIXME one day: We recompute usage.... :( */
-         cnst->usage = 0.0;
-         make_elem_inactive(elem);
-         xbt_swag_foreach(elem, elem_list) {
-           if (elem->variable->weight <= 0)
-             break;
-           if (elem->variable->value > 0)
-             break;
-           if ((elem->value > 0)) {
-             if (cnst->usage < elem->value / elem->variable->weight)
-               cnst->usage = elem->value / elem->variable->weight;
-             DEBUG2("Constraint Usage %p : %f", cnst, cnst->usage);
-             make_elem_active(elem);
-           }
-         }
-       }
+        elem = &var->cnsts[i];
+        cnst = elem->constraint;
+        if (cnst->shared) {
+          double_update(&(cnst->remaining), elem->value * var->value);
+          double_update(&(cnst->usage), elem->value / var->weight);
+          make_elem_inactive(elem);
+        } else {                /* FIXME one day: We recompute usage.... :( */
+          cnst->usage = 0.0;
+          make_elem_inactive(elem);
+          elem_list = &(cnst->element_set);
+          xbt_swag_foreach(elem, elem_list) {
+            if (elem->variable->weight <= 0)
+              break;
+            if (elem->variable->value > 0)
+              break;
+            if ((elem->value > 0)) {
+              cnst->usage=MAX(cnst->usage,elem->value / elem->variable->weight);
+              DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
+              make_elem_active(elem);
+            }
+          }
+        }
       }
       xbt_swag_remove(var, var_list);
     }
 
     /* Find out which variables reach the maximum */
-    cnst_list = &(sys->active_constraint_set);
+    cnst_list =
+      sys->selective_update_active ? &(sys->modified_constraint_set) :
+      &(sys->active_constraint_set);
     min_usage = -1;
+    min_bound = -1;
     xbt_swag_foreach(cnst, cnst_list) {
       saturated_constraint_set_update(sys, cnst, &min_usage);
     }
@@ -568,6 +612,9 @@ void lmm_solve(lmm_system_t sys)
   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 
   sys->modified = 0;
+  if (sys->selective_update_active)
+    lmm_remove_all_modified_set(sys);
+
   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
     lmm_print(sys);
   }
@@ -576,14 +623,15 @@ void lmm_solve(lmm_system_t sys)
 /* Not a O(1) function */
 
 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
-               lmm_variable_t var, double value)
+                lmm_variable_t var, double value)
 {
   int i;
 
-  sys->modified = 1;
   for (i = 0; i < var->cnsts_number; i++)
     if (var->cnsts[i].constraint == cnst) {
       var->cnsts[i].value = value;
+      sys->modified = 1;
+      lmm_update_modified_set(sys, cnst);
       return;
     }
 }
@@ -601,38 +649,27 @@ void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
  *
  */
 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
-                              double bound)
+                               double bound)
 {
+  int i;
+
   sys->modified = 1;
   var->bound = bound;
-}
 
-/** \brief Add the value delta to var->df (the sum of latencies).
- * 
- *  \param sys the lmm_system_t associated
- *  \param var the lmm_variable_t which need to updated
- *  \param delta the variation of the latency
- * 
- *  Add the value delta to var->df (the sum of latencys associated to the
- *  flow). Whenever this function is called a change is  signed in the system. To
- *  avoid false system changing detection it is a good idea to test 
- *  (delta != 0) before calling it.
- *
- */
-void lmm_update_variable_latency(lmm_system_t sys, lmm_variable_t var,
-                                double delta)
-{
-  sys->modified = 1;
-  var->df += delta;
+  for (i = 0; i < var->cnsts_number; i++)
+    lmm_update_modified_set(sys, var->cnsts[i].constraint);
+
 }
 
+
 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
-                               double weight)
+                                double weight)
 {
   int i;
   lmm_element_t elem;
 
-  if(weight==var->weight) return;
+  if (weight == var->weight)
+    return;
   XBT_IN3("(sys=%p, var=%p, weight=%f)", sys, var, weight);
   sys->modified = 1;
   var->weight = weight;
@@ -649,37 +686,98 @@ void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
     else
       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
+
+    lmm_update_modified_set(sys, elem->constraint);
   }
-  if(!weight)
+  if (!weight)
     var->value = 0.0;
 
   XBT_OUT;
 }
 
-double lmm_get_variable_weight(lmm_variable_t var)
+XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 {
   return var->weight;
 }
 
-void lmm_update_constraint_bound(lmm_system_t sys, lmm_constraint_t cnst,
-                                double bound)
+XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys, lmm_constraint_t cnst,
+                                 double bound)
 {
   sys->modified = 1;
+  lmm_update_modified_set(sys, cnst);
   cnst->bound = bound;
 }
 
-int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
+XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 {
   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 }
 
-lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
+XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
 {
   return xbt_swag_getFirst(&(sys->active_constraint_set));
 }
 
-lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
-                                               lmm_constraint_t cnst)
+XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
+                                                lmm_constraint_t cnst)
 {
   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 }
+
+/** \brief Update the constraint set propagating recursively to
+ *  other constraints so the system should not be entirely computed.
+ *
+ *  \param sys the lmm_system_t
+ *  \param cnst the lmm_constraint_t affected by the change
+ *
+ *  A recursive algorithm to optimize the system recalculation selecting only
+ *  constraints that have changed. Each constraint change is propagated
+ *  to the list of constraints for each variable.
+ */
+static void lmm_update_modified_set(lmm_system_t sys, lmm_constraint_t cnst)
+{
+  lmm_element_t elem = NULL;
+  lmm_variable_t var = NULL;
+  xbt_swag_t elem_list = NULL;
+  int i;
+
+  /* return if selective update isn't active */
+  if (!sys->selective_update_active)
+    return;
+
+  //DEBUG1("Updating modified constraint set with constraint %d", cnst->id_int);
+
+  if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
+    return;
+
+  //DEBUG1("Inserting into modified constraint set %d", cnst->id_int);
+
+  /* add to modified set */
+  xbt_swag_insert(cnst, &(sys->modified_constraint_set));
+
+  elem_list = &(cnst->element_set);
+  xbt_swag_foreach(elem, elem_list) {
+    var = elem->variable;
+    for (i = 0; i < var->cnsts_number; i++)
+      if (cnst != var->cnsts[i].constraint) {
+        //DEBUG2("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
+        lmm_update_modified_set(sys, var->cnsts[i].constraint);
+      }
+  }
+}
+
+/** \brief Remove all constraints of the modified_constraint_set.
+ *
+ *  \param sys the lmm_system_t
+ */
+static void lmm_remove_all_modified_set(lmm_system_t sys)
+{
+  lmm_element_t elem = NULL;
+  lmm_element_t elem_next = NULL;
+  xbt_swag_t elem_list = NULL;
+
+  elem_list = &(sys->modified_constraint_set);
+  xbt_swag_foreach_safe(elem, elem_next, elem_list) {
+    xbt_swag_remove(elem, elem_list);
+  }
+}