-/* Copyright (c) 2004-2013. The SimGrid Team.
+/* Copyright (c) 2004-2015. The SimGrid Team.
* All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
#ifndef _SURF_MAXMIN_H
#define _SURF_MAXMIN_H
-#include "portable.h"
+#include "src/portable.h"
#include "xbt/misc.h"
+#include "xbt/asserts.h"
#include "surf/datatypes.h"
#include <math.h>
/** @addtogroup SURF_lmm
* @details
- * A linear maxmin solver to resolves inequations systems.
- *
- * A system is composed of variables, constraints and elements linking them.
+ * A linear maxmin solver to resolve inequations systems.
+ *
+ * Most SimGrid model rely on a "fluid/steady-state" modeling that
+ * simulate the sharing of resources between actions at relatively
+ * coarse-grain. Such sharing is generally done by solving a set of
+ * linear inequations. Let's take an example and assume we have the
+ * variables \f$x_1\f$, \f$x_2\f$, \f$x_3\f$, and \f$x_4\f$ . Let's
+ * say that \f$x_1\f$ and \f$x_2\f$ correspond to activities running
+ * and the same CPU \f$A\f$ whose capacity is \f$C_A\f$. In such a
+ * case, we need to enforce:
+ *
+ * \f[ x_1 + x_2 \leq C_A \f]
+ *
+ * Likewise, if \f$x_3\f$ (resp. \f$x_4\f$) corresponds to a network
+ * flow \f$F_3\f$ (resp. \f$F_4\f$) that goes through a set of links
+ * \f$L_1\f$ and \f$L_2\f$ (resp. \f$L_2\f$ and \f$L_3\f$), then we
+ * need to enforce:
+ *
+ * \f[ x_3 \leq C_{L_1} \f]
+ * \f[ x_3 + x_4 \leq C_{L_2} \f]
+ * \f[ x_4 \leq C_{L_3} \f]
+ *
+ * One could set every variable to 0 to make sure the constraints are
+ * satisfied but this would obviously not be very realistic. A
+ * possible objective is to try to maximize the minimum of the
+ * \f$x_i\f$ . This ensures that all the \f$x_i\f$ are positive and "as
+ * large as possible".
+ *
+ * This is called *max-min fairness* and is the most commonly used
+ * objective in SimGrid. Another possibility is to maximize
+ * \f$\sum_if(x_i)\f$, where \f$f\f$ is a strictly increasing concave
+ * function.
+ *
* Constraint:
* - bound (set)
* - shared (set)
* - usage (computed)
+ *
* Variable:
* - weight (set)
* - bound (set)
* - value (computed)
+ *
* Element:
* - value (set)
*
* var1.weight * var1.value * elem1.value + var2.weight * var2.value * elem2.value <= cons1.bound
* var2.weight * var2.value * elem3.value + var3.weight * var3.value * elem4.value <= cons2.bound
*
- * where `var1.value`, `var2.value` and `var3.value` are the unknown values
+ * where `var1.value`, `var2.value` and `var3.value` are the unknown values.
*
- * if a constraint is not shared the sum is replace by a max
+ * If a constraint is not shared, the sum is replaced by a max.
+ * For example, a third non-shared constraint `cons3` and the associated elements `elem5` and `elem6` could write as:
+ *
+ * max( var1.weight * var1.value * elem5.value , var3.weight * var3.value * elem6.value ) <= cons3.bound
+ *
+ * This is usefull for the sharing of resources for various models.
+ * For instance, for the network model, each link is associated
+ * to a constraint and each communication to a variable.
*
- * Its usefull for the sharing of resources for various models.
- * For instance for the network model the link are associated
- * to consrtaint and the communications to variables.
*/
-extern double sg_maxmin_precision;
-#define MAXMIN_PRECISION sg_maxmin_precision
-static XBT_INLINE void double_update(double *variable, double value)
+XBT_PUBLIC_DATA(double) sg_maxmin_precision;
+XBT_PUBLIC_DATA(double) sg_surf_precision;
+
+static XBT_INLINE void double_update(double *variable, double value, double precision)
{
+ //printf("Updating %g -= %g +- %g\n",*variable,value,precision);
+ //xbt_assert(value==0 || value>precision);
+ //Check that precision is higher than the machine-dependent size of the mantissa. If not, brutal rounding may happen, and the precision mechanism is not active...
+ //xbt_assert(*variable< (2<<DBL_MANT_DIG)*precision && FLT_RADIX==2);
*variable -= value;
- if (*variable < MAXMIN_PRECISION)
+ if (*variable < precision)
*variable = 0.0;
}
-static XBT_INLINE int double_positive(double value)
+static XBT_INLINE int double_positive(double value, double precision)
{
- return (value > MAXMIN_PRECISION);
+ return (value > precision);
}
-static XBT_INLINE int double_equals(double value1, double value2)
+static XBT_INLINE int double_equals(double value1, double value2, double precision)
{
- return (fabs(value1 - value2) < MAXMIN_PRECISION);
+ return (fabs(value1 - value2) < precision);
}
SG_BEGIN_DECL()
*
* @param cnst The constraint to share
*/
-void lmm_constraint_shared(lmm_constraint_t cnst);
+XBT_PUBLIC(void) lmm_constraint_shared(lmm_constraint_t cnst);
/**
* @brief Check if a constraint is shared (shared by default)
* @param cnst The constraint to share
* @return 1 if shared, 0 otherwise
*/
-int lmm_constraint_is_shared(lmm_constraint_t cnst);
+XBT_PUBLIC(int) lmm_constraint_sharing_policy(lmm_constraint_t cnst);
/**
* @brief Free a constraint
* @param sys The system associated to the constraint
* @param cnst The constraint to free
*/
-void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst);
+XBT_PUBLIC(void) lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst);
/**
* @brief Get the usage of the constraint after the last lmm solve
* @param cnst A constraint
* @return The usage of the constraint
*/
-double lmm_constraint_get_usage(lmm_constraint_t cnst);
+XBT_PUBLIC(double) lmm_constraint_get_usage(lmm_constraint_t cnst);
/**
* @brief Create a new Linear MaxMin variable
* @param var A variable
* @param value The value to add to the coefficient associated to the variable in the constraint
*/
-void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
+XBT_PUBLIC(void) lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
lmm_variable_t var, double value);
-/**
- * @brief Change the value of the coefficient between a constraint and a variable
- *
- * @param sys A system
- * @param cnst A constraint
- * @param var A variable
- * @param value The new value of the coefficient between a constraint and a variable
- */
-void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
- lmm_variable_t var, double value);
-
/**
* @brief Get the numth constraint associated to the variable
*
* @param num The rank of constraint we want to get
* @return The numth constraint
*/
-lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
+XBT_PUBLIC(lmm_constraint_t) lmm_get_cnst_from_var(lmm_system_t sys,
lmm_variable_t var, int num);
/**
* @param num The rank of constraint we want to get
* @return The numth constraint
*/
-double lmm_get_cnst_weight_from_var(lmm_system_t sys, lmm_variable_t var,
+XBT_PUBLIC(double) lmm_get_cnst_weight_from_var(lmm_system_t sys, lmm_variable_t var,
int num);
/**
* @param var A variable
* @return The number of constraint associated to the variable
*/
-int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var);
+XBT_PUBLIC(int) lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var);
/**
* @brief Get a var associated to a constraint
* @param elem A element of constraint of the constraint or NULL
* @return A variable associated to a constraint
*/
-lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
+XBT_PUBLIC(lmm_variable_t) lmm_get_var_from_cnst(lmm_system_t sys,
lmm_constraint_t cnst,
lmm_element_t * elem);
+/**
+ * @brief Get a var associated to a constraint
+ * @details Get the first variable of the next variable of elem if elem is not NULL
+ *
+ * @param cnst A constraint
+ * @param elem A element of constraint of the constraint or NULL
+ * @param nextelem A element of constraint of the constraint or NULL, the one after elem
+ * @param numelem parameter representing the number of elements to go
+ *
+ * @return A variable associated to a constraint
+ */
+XBT_PUBLIC(lmm_variable_t) lmm_get_var_from_cnst_safe(lmm_system_t /*sys*/,
+ lmm_constraint_t cnst,
+ lmm_element_t * elem,
+ lmm_element_t * nextelem,
+ int * numelem);
+
/**
* @brief Get the first active constraint of a system
*
* @param sys A system
* @return The first active constraint
*/
-lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys);
+XBT_PUBLIC(lmm_constraint_t) lmm_get_first_active_constraint(lmm_system_t sys);
/**
* @brief Get the next active constraint of a constraint in a system
*
* @return The next active constraint
*/
-lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
+XBT_PUBLIC(lmm_constraint_t) lmm_get_next_active_constraint(lmm_system_t sys,
lmm_constraint_t cnst);
#ifdef HAVE_LATENCY_BOUND_TRACKING
* @param cnst A constraint
* @return The data associated to the constraint
*/
-void *lmm_constraint_id(lmm_constraint_t cnst);
+XBT_PUBLIC(void *) lmm_constraint_id(lmm_constraint_t cnst);
/**
* @brief Get the data associated to a variable
*
- * @param cnst A variable
+ * @param var A variable
* @return The data associated to the variable
*/
-void *lmm_variable_id(lmm_variable_t var);
+XBT_PUBLIC(void *) lmm_variable_id(lmm_variable_t var);
/**
* @brief Update the value of element linking the constraint and the variable
* @param var A variable
* @param value The new value
*/
-void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
+XBT_PUBLIC(void) lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
lmm_variable_t var, double value);
/**
* @param var A constraint
* @param bound The new bound
*/
-void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
+XBT_PUBLIC(void) lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
double bound);
/**
* @brief Update the weight of a variable
*
* @param sys A system
- * @param var A variable
+ * @param var A variable
* @param weight The new weight of the variable
*/
XBT_PUBLIC(void) lmm_update_variable_weight(lmm_system_t sys,
* @param var A variable
* @return The weight of the variable
*/
-double lmm_get_variable_weight(lmm_variable_t var);
+XBT_PUBLIC(double) lmm_get_variable_weight(lmm_variable_t var);
/**
* @brief Update a constraint bound
* @param cnst A constraint
* @return [description]
*/
-int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst);
+XBT_PUBLIC(int) lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst);
/**
* @brief Solve the lmm system
