X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/99b517a9c666f4882c8afe1fee51eae6238952c5..6a6157abf9619875297ff1d16c1e5c63c526d4c1:/src/surf/maxmin.c

diff --git a/src/surf/maxmin.c b/src/surf/maxmin.c
index 7660fb1377..78e34a1156 100644
--- a/src/surf/maxmin.c
+++ b/src/surf/maxmin.c
@@ -1,23 +1,32 @@
-/* Authors: Arnaud Legrand                                                  */
+/* Copyright (c) 2004, 2005, 2006, 2007, 2008, 2009, 2010. The SimGrid Team.
+ * All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
-   under the terms of the license (GNU LGPL) which comes with this package. */
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
 
 #include "xbt/sysdep.h"
-#include "xbt/error.h"
+#include "xbt/log.h"
+#include "xbt/mallocator.h"
 #include "maxmin_private.h"
 #include <stdlib.h>
-
-/* extern lmm_system_t Sys; */
-/* extern lmm_constraint_t L1; */
-/* extern lmm_constraint_t L2; */
-/* extern lmm_constraint_t L3; */
-
-/* extern lmm_variable_t R_1_2_3; */
-/* extern lmm_variable_t R_1; */
-/* extern lmm_variable_t R_2; */
-/* extern lmm_variable_t R_3; */
-
+#include <stdio.h>              /* sprintf */
+#include <math.h>
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
+                                "Logging specific to SURF (maxmin)");
+
+double sg_maxmin_precision = 0.00001;
+
+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;
+extern xbt_swag_t keep_track;
 
 lmm_system_t lmm_system_new(void)
 {
@@ -27,18 +36,31 @@ 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;
+
+  XBT_DEBUG("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(65536,
+                                              lmm_variable_mallocator_new_f,
+                                              lmm_variable_mallocator_free_f,
+                                              lmm_variable_mallocator_reset_f);
 
   return l;
 }
@@ -48,85 +70,159 @@ 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))) {
+    XBT_WARN
+        ("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);
 
-  xbt_free(sys);
+  xbt_mallocator_free(sys->variable_mallocator);
+  free(sys);
 }
 
-static void lmm_var_free(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;
 
+  XBT_IN("(sys=%p, var=%p)", sys, var);
+  sys->modified = 1;
+
   for (i = 0; i < var->cnsts_number; i++) {
     elem = &var->cnsts[i];
-    xbt_swag_extract(elem, &(elem->constraint->element_set));
-    if (xbt_swag_size(&(elem->constraint->element_set)))
+    xbt_swag_remove(elem, &(elem->constraint->element_set));
+    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);
   }
-  xbt_free(var->cnsts);
-  xbt_free(var);
+  var->cnsts_number = 0;
+  XBT_OUT();
 }
 
-static void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
+static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
 {
-/*   xbt_assert0(xbt_fifo_size(&(cnst->row)), */
-/* 		 "This list should be empty!"); */
+
+  lmm_variable_disable(sys, var);
+  xbt_mallocator_release(sys->variable_mallocator, var);
+}
+
+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!"); */
   remove_active_constraint(sys, cnst);
-  xbt_free(cnst);
+  free(cnst);
 }
 
 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
-				    xbt_maxmin_float_t 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 = 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;
+  cnst->shared = 1;
   insert_constraint(sys, cnst);
 
-  cnst->id = id;
-
   return cnst;
 }
 
-void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
+XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
+{
+  cnst->shared = 0;
+}
+
+XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
+{
+  return (cnst->shared);
+}
+
+XBT_INLINE void lmm_constraint_free(lmm_system_t sys,
+                                    lmm_constraint_t cnst)
 {
   remove_constraint(sys, cnst);
   lmm_cnst_free(sys, cnst);
 }
 
+static void *lmm_variable_mallocator_new_f(void)
+{
+  lmm_variable_t var = xbt_new(s_lmm_variable_t, 1);
+  var->cnsts = NULL; /* will be created by realloc */
+  return var;
+}
+
+static void lmm_variable_mallocator_free_f(void *var)
+{
+  xbt_free(((lmm_variable_t) var)->cnsts);
+  xbt_free(var);
+}
+
+static void lmm_variable_mallocator_reset_f(void *var)
+{
+  /* lmm_variable_new() initializes everything */
+}
+
 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
-				xbt_maxmin_float_t weight,
-				xbt_maxmin_float_t bound,
-				int number_of_constraints)
+                                double weight,
+                                double bound, int number_of_constraints)
 {
   lmm_variable_t var = NULL;
+  int i;
 
-  var = xbt_new0(s_lmm_variable_t, 1);
-/*   var->id = id; */
-  var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
+  XBT_IN("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
+          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_realloc(var->cnsts, number_of_constraints * sizeof(s_lmm_element_t));
+  for (i = 0; i < number_of_constraints; i++) {
+    var->cnsts[i].element_set_hookup.next = NULL;
+    var->cnsts[i].element_set_hookup.prev = NULL;
+    var->cnsts[i].active_element_set_hookup.next = NULL;
+    var->cnsts[i].active_element_set_hookup.prev = NULL;
+    var->cnsts[i].constraint = NULL;
+    var->cnsts[i].variable = NULL;
+    var->cnsts[i].value = 0.0;
+  }
   var->cnsts_size = number_of_constraints;
-  /* var->cnsts_number = 0; *//* Useless because of the calloc  */
+  var->cnsts_number = 0;
   var->weight = weight;
   var->bound = bound;
-  var->value = -1;
-  insert_variable(sys, var);
-
-  var->id = id;
-
+  var->value = 0.0;
+
+  var->mu = 0.0;
+  var->new_mu = 0.0;
+  var->func_f = func_f_def;
+  var->func_fp = func_fp_def;
+  var->func_fpi = func_fpi_def;
+
+  var->variable_set_hookup.next = NULL;
+  var->variable_set_hookup.prev = NULL;
+  var->saturated_variable_set_hookup.next = NULL;
+  var->saturated_variable_set_hookup.prev = NULL;
+
+  if (weight)
+    xbt_swag_insert_at_head(var, &(sys->variable_set));
+  else
+    xbt_swag_insert_at_tail(var, &(sys->variable_set));
+  XBT_OUT();
   return var;
 }
 
@@ -136,18 +232,24 @@ void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
   lmm_var_free(sys, var);
 }
 
-xbt_maxmin_float_t lmm_variable_getvalue(lmm_variable_t var)
+XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 {
   return (var->value);
 }
 
+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, xbt_maxmin_float_t value)
+                lmm_variable_t var, double value)
 {
   lmm_element_t elem = NULL;
 
-  if (var->cnsts_number >= var->cnsts_size)
-    abort();
+  sys->modified = 1;
+
+  xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 
   elem = &(var->cnsts[var->cnsts_number++]);
 
@@ -155,34 +257,125 @@ void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
   elem->constraint = cnst;
   elem->variable = var;
 
-  insert_elem_in_constraint(elem);
+  if (var->weight)
+    xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
+  else
+    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)
+{
+  int i;
+  sys->modified = 1;
+
+  for (i = 0; i < var->cnsts_number; i++)
+    if (var->cnsts[i].constraint == 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);
+    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)
+{
+  int i;
+
+  for (i = 0; i < var->cnsts_number; i++)
+    if (var->cnsts[i].constraint == cnst)
+      break;
+
+  if (i < var->cnsts_number) {
+    var->cnsts[i].value = value;
+    sys->modified = 1;
+    lmm_update_modified_set(sys, cnst);
+  } else
+    DIE_IMPOSSIBLE;
+}
+
+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);
+  else
+    return NULL;
+}
+
+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)
+{
+  if (!(*elem))
+    *elem = xbt_swag_getFirst(&(cnst->element_set));
+  else
+    *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
+  if (*elem)
+    return (*elem)->variable;
+  else
+    return NULL;
+}
+
+XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
+{
+  return cnst->id;
 }
 
-static void saturated_constraints_update(lmm_system_t sys,
-					 lmm_constraint_t cnst,
-					 xbt_maxmin_float_t * min_usage)
+XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
+{
+  return var->id;
+}
+
+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;
 
-  if (cnst->remaining <= 0)
+  XBT_IN("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
+  if (cnst->usage <= 0) {
+    XBT_OUT();
+    return;
+  }
+  if (cnst->remaining <= 0) {
+    XBT_OUT();
     return;
+  }
   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
-    xbt_swag_t active_elem_list = &(cnst->active_element_set);
-
     *min_usage = cnst->remaining / cnst->usage;
+    XBT_LOG(xbt_log_priority_trace,
+         "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_remove(useless_cnst, &(sys->saturated_constraint_set));
 
-    while (xbt_swag_extract
-	   (useless_cnst, &(sys->saturated_constraint_set))) {
-    }
     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
   } else if (*min_usage == cnst->remaining / cnst->usage) {
     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
   }
+  XBT_OUT();
 }
 
-static void saturated_variables_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;
@@ -191,50 +384,178 @@ static void saturated_variables_update(lmm_system_t sys)
 
   cnst_list = &(sys->saturated_constraint_set);
   while ((cnst = xbt_swag_getFirst(cnst_list))) {
-/*   xbt_swag_foreach(cnst, cnst_list) { */
     elem_list = &(cnst->active_element_set);
-    xbt_swag_foreach(elem, elem_list)
-	xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
-    xbt_swag_extract(cnst, cnst_list);
+    xbt_swag_foreach(elem, elem_list) {
+      if (elem->variable->weight <= 0)
+        break;
+      if ((elem->value > 0))
+        xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
+    }
+    xbt_swag_remove(cnst, cnst_list);
   }
-
 }
 
-void lmm_solve(lmm_system_t sys)
+void lmm_print(lmm_system_t sys)
 {
-  lmm_variable_t var = NULL;
   lmm_constraint_t cnst = NULL;
   lmm_element_t elem = NULL;
+  lmm_variable_t var = NULL;
   xbt_swag_t cnst_list = NULL;
   xbt_swag_t var_list = NULL;
   xbt_swag_t elem_list = NULL;
-  xbt_maxmin_float_t min_usage = -1;
+  char print_buf[1024];
+  char *trace_buf = xbt_malloc0(sizeof(char));
+  double sum = 0.0;
 
-  /* Init */
+  /* Printing Objective */
   var_list = &(sys->variable_set);
+  sprintf(print_buf, "MAX-MIN ( ");
+  trace_buf =
+      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+  strcat(trace_buf, print_buf);
   xbt_swag_foreach(var, var_list) {
-    var->value = -1;
+    sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
+    trace_buf =
+        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);
+  strcat(trace_buf, print_buf);
+  fprintf(stderr, "%s", trace_buf);
+  //XBT_DEBUG("%20s", trace_buf); FIXME
+  trace_buf[0] = '\000';
+
+  XBT_DEBUG("Constraints");
+  /* Printing Constraints */
+  cnst_list = &(sys->active_constraint_set);
+  xbt_swag_foreach(cnst, cnst_list) {
+    sum = 0.0;
+    elem_list = &(cnst->element_set);
+    sprintf(print_buf, "\t");
+    trace_buf =
+        xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
+    strcat(trace_buf, print_buf);
+    sprintf(print_buf, "%s(",(cnst->shared)?"":"max");
+    trace_buf =
+      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.'%d'(%f) %s ", elem->value,
+              elem->variable->id_int, elem->variable->value,(cnst->shared)?"+":",");
+      trace_buf =
+          xbt_realloc(trace_buf,
+                      strlen(trace_buf) + strlen(print_buf) + 1);
+      strcat(trace_buf, print_buf);
+      if(cnst->shared) 
+	sum += elem->value * elem->variable->value;
+      else 
+	sum = MAX(sum,elem->value * elem->variable->value);
+    }
+    sprintf(print_buf, "0) <= %f ('%d')", cnst->bound, cnst->id_int);
+    trace_buf =
+        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);
+      strcat(trace_buf, print_buf);
+    }
+    //   XBT_DEBUG("%s", trace_buf);
+    fprintf(stderr, "%s\n", trace_buf);
+    trace_buf[0] = '\000';
+    xbt_assert3(!double_positive(sum - cnst->bound),
+                "Incorrect value (%f is not smaller than %f): %g",
+                sum, cnst->bound, sum - cnst->bound);
   }
 
+  XBT_DEBUG("Variables");
+  /* Printing Result */
+  xbt_swag_foreach(var, var_list) {
+    if (var->bound > 0) {
+      XBT_DEBUG("'%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 {
+      XBT_DEBUG("'%d'(%f) : %f", var->id_int, var->weight, var->value);
+    }
+  }
 
-  /* Compute Usage and store the variables that reach the maximum */
+  free(trace_buf);
+}
 
-  cnst_list = &(sys->active_constraint_set);
+void lmm_solve(lmm_system_t sys)
+{
+  lmm_variable_t var = NULL;
+  lmm_constraint_t cnst = NULL;
+  lmm_element_t elem = NULL;
+  xbt_swag_t cnst_list = NULL;
+  xbt_swag_t var_list = NULL;
+  xbt_swag_t elem_list = NULL;
+  double min_usage = -1;
+  double min_bound = -1;
+
+  if (!(sys->modified))
+    return;
+
+  XBT_IN("(sys=%p)", sys);
+
+  /*
+   * Compute Usage and store the variables that reach the maximum.
+   */
+  cnst_list =
+      sys->
+      selective_update_active ? &(sys->modified_constraint_set) :
+      &(sys->active_constraint_set);
+
+  XBT_DEBUG("Active constraints : %d", xbt_swag_size(cnst_list));
+  /* Init: Only modified code portions */
   xbt_swag_foreach(cnst, cnst_list) {
-    /* INIT */
     elem_list = &(cnst->element_set);
+    //XBT_DEBUG("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;
+    }
+  }
+
+  xbt_swag_foreach(cnst, cnst_list) {
+    /* INIT */
     cnst->remaining = cnst->bound;
+    if (cnst->remaining == 0)
+      continue;
     cnst->usage = 0;
+    elem_list = &(cnst->element_set);
     xbt_swag_foreach(elem, elem_list) {
-      cnst->usage += elem->value / elem->variable->weight;
-      insert_active_elem_in_constraint(elem);
+      /* 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;
+      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;
+
+        make_elem_active(elem);
+        if(keep_track){
+            xbt_swag_insert((elem->variable)->id, keep_track);
+        }
+      }
     }
-
+    XBT_DEBUG("Constraint Usage '%d' : %f", cnst->id_int, cnst->usage);
     /* Saturated constraints update */
-    saturated_constraints_update(sys, cnst, &min_usage);
+    saturated_constraint_set_update(sys, cnst, &min_usage);
   }
-
-  saturated_variables_update(sys);
+  saturated_variable_set_update(sys);
 
   /* Saturated variables update */
 
@@ -242,12 +563,21 @@ void lmm_solve(lmm_system_t sys)
     /* Fix the variables that have to be */
     var_list = &(sys->saturated_variable_set);
 
-
     xbt_swag_foreach(var, var_list) {
+      if (var->weight <= 0.0)
+        DIE_IMPOSSIBLE;
       /* First check if some of these variables have reach their upper
          bound and update min_usage accordingly. */
-      if ((var->bound > 0) && (var->bound / var->weight < min_usage)) {
-	min_usage = var->bound / var->weight;
+      XBT_DEBUG
+          ("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)) {
+        if (min_bound < 0)
+          min_bound = var->bound;
+        else
+          min_bound = MIN(min_bound, var->bound);
+        XBT_DEBUG("Updated min_bound=%f", min_bound);
       }
     }
 
@@ -255,78 +585,245 @@ void lmm_solve(lmm_system_t sys)
     while ((var = xbt_swag_getFirst(var_list))) {
       int i;
 
-      var->value = min_usage / var->weight;
+      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;
+        }
+      }
+      XBT_DEBUG("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;
-	cnst->remaining -= elem->value * var->value;
-	cnst->usage -= elem->value / var->weight;
-	remove_active_elem_in_constraint(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);
+              XBT_DEBUG("Constraint Usage %d : %f", cnst->id_int,
+                     cnst->usage);
+              make_elem_active(elem);
+            }
+          }
+        }
       }
-      xbt_swag_extract(var, var_list);
+      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_constraints_update(sys, cnst, &min_usage);
+      saturated_constraint_set_update(sys, cnst, &min_usage);
     }
-    saturated_variables_update(sys);
+    saturated_variable_set_update(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);
+  }
+  XBT_OUT();
 }
 
 /* Not a O(1) function */
 
 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
-		lmm_variable_t var, xbt_maxmin_float_t value)
+                lmm_variable_t var, double value)
 {
   int i;
-  lmm_element_t elem = NULL;
 
   for (i = 0; i < var->cnsts_number; i++)
     if (var->cnsts[i].constraint == cnst) {
-      elem->value = value;
+      var->cnsts[i].value = value;
+      sys->modified = 1;
+      lmm_update_modified_set(sys, cnst);
       return;
     }
 }
 
-void lmm_update_variable_bound(lmm_variable_t var,
-			       xbt_maxmin_float_t bound)
+/** \brief Attribute the value bound to var->bound.
+ * 
+ *  \param sys the lmm_system_t
+ *  \param var the lmm_variable_t
+ *  \param bound the new bound to associate with var
+ * 
+ *  Makes var->bound equal to bound. 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 
+ *  (bound != 0) before calling it.
+ *
+ */
+void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
+                               double bound)
 {
+  int i;
+
+  sys->modified = 1;
   var->bound = bound;
+
+  for (i = 0; i < var->cnsts_number; i++)
+    lmm_update_modified_set(sys, var->cnsts[i].constraint);
+
 }
 
-void lmm_update_variable_weight(lmm_variable_t var,
-				xbt_maxmin_float_t weight)
+
+void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
+                                double weight)
 {
+  int i;
+  lmm_element_t elem;
+
+  if (weight == var->weight)
+    return;
+  XBT_IN("(sys=%p, var=%p, weight=%f)", sys, var, weight);
+  sys->modified = 1;
   var->weight = weight;
+  xbt_swag_remove(var, &(sys->variable_set));
+  if (weight)
+    xbt_swag_insert_at_head(var, &(sys->variable_set));
+  else
+    xbt_swag_insert_at_tail(var, &(sys->variable_set));
+
+  for (i = 0; i < var->cnsts_number; i++) {
+    elem = &var->cnsts[i];
+    xbt_swag_remove(elem, &(elem->constraint->element_set));
+    if (weight)
+      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)
+    var->value = 0.0;
+
+  XBT_OUT();
+}
+
+XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
+{
+  return var->weight;
 }
 
-void lmm_update_constraint_bound(lmm_constraint_t cnst,
-				 xbt_maxmin_float_t 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;
 }
 
+XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
+{
+  return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
+}
+
+XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t
+                                                            sys)
+{
+  return xbt_swag_getFirst(&(sys->active_constraint_set));
+}
+
+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);
+}
+
+#ifdef HAVE_LATENCY_BOUND_TRACKING
+XBT_INLINE int lmm_is_variable_limited_by_latency(lmm_variable_t var)
+{
+  return (double_equals(var->bound, var->value));
+}
+#endif
+
+
+/** \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;
+
+  //XBT_DEBUG("Updating modified constraint set with constraint %d", cnst->id_int);
+
+  if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
+    return;
+
+  //XBT_DEBUG("Inserting into modified constraint set %d", cnst->id_int);
 
+  /* add to modified set */
+  xbt_swag_insert(cnst, &(sys->modified_constraint_set));
 
-/* void lmm_print(lmm_system_t sys) */
-/* { */
-/*   lmm_variable_t var = NULL; */
-/*   lmm_constraint_t cnst = NULL; */
-/*   lmm_element_t elem = NULL; */
-/*   xbt_swag_t cnst_list = NULL; */
-/*   xbt_swag_t var_list = NULL; */
-/*   xbt_swag_t elem_list = NULL; */
+  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) {
+        //XBT_DEBUG("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
+        lmm_update_modified_set(sys, var->cnsts[i].constraint);
+      }
+  }
+}
 
-/*   var_list = &(sys->variable_set); */
-/*   xbt_swag_foreach(var, var_list) { */
-/*     printf("%s : {\n",var->id); */
-/*     printf("\t %s : {\n",var->id); */
-/*   } */
-/* } */
+/** \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);
+  }
+}