-/* $Id$ */
-
-/* Copyright (c) 2004 Arnaud Legrand. All rights reserved. */
+/* Copyright (c) 2004-2015. 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. */
#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 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)
+ *
+ * A possible system could be:
+ * - three variables: `var1`, `var2`, `var3`
+ * - two constraints: `cons1`, `cons2`
+ * - four elements linking:
+ * - `elem1` linking `var1` and `cons1`
+ * - `elem2` linking `var2` and `cons1`
+ * - `elem3` linking `var2` and `cons2`
+ * - `elem4` linking `var3` and `cons2`
+ *
+ * And the corresponding inequations will be:
+ *
+ * var1.value <= var1.bound
+ * var2.value <= var2.bound
+ * var3.value <= var3.bound
+ * 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.
+ *
+ * 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.
+ *
+ */
-#define MAXMIN_PRECISION 0.00001
-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);
}
-XBT_PUBLIC(lmm_system_t) lmm_system_new(void);
+static XBT_INLINE int double_equals(double value1, double value2, double precision)
+{
+ return (fabs(value1 - value2) < precision);
+}
+
+SG_BEGIN_DECL()
+
+/** @{ @ingroup SURF_lmm */
+/**
+ * @brief Create a new Linear MaxMim system
+ *
+ * @param selective_update [description]
+ */
+XBT_PUBLIC(lmm_system_t) lmm_system_new(int selective_update);
+
+/**
+ * @brief Free an existing Linear MaxMin system
+ *
+ * @param sys The lmm system to free
+ */
XBT_PUBLIC(void) lmm_system_free(lmm_system_t sys);
- void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var);
+/**
+ * @brief Create a new Linear MaxMin constraint
+ *
+ * @param sys The system in which we add a constraint
+ * @param id Data associated to the constraint (e.g.: a network link)
+ * @param bound_value The bound value of the constraint
+ */
XBT_PUBLIC(lmm_constraint_t) lmm_constraint_new(lmm_system_t sys, void *id,
double bound_value);
- void lmm_constraint_shared(lmm_constraint_t cnst);
- int lmm_constraint_is_shared(lmm_constraint_t cnst);
- void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst);
+/**
+ * @brief Share a constraint
+ * @details [long description]
+ *
+ * @param cnst The constraint to share
+ */
+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
+ */
+XBT_PUBLIC(int) lmm_constraint_is_shared(lmm_constraint_t cnst);
+
+/**
+ * @brief Free a constraint
+ *
+ * @param sys The system associated to the constraint
+ * @param cnst The constraint to free
+ */
+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
+ */
+XBT_PUBLIC(double) lmm_constraint_get_usage(lmm_constraint_t cnst);
+
+/**
+ * @brief Create a new Linear MaxMin variable
+ *
+ * @param sys The system in which we add a constaint
+ * @param id Data associated to the variable (e.g.: a network communication)
+ * @param weight_value The weight of the variable (0.0 if not used)
+ * @param bound The maximum value of the variable (-1.0 if no maximum value)
+ * @param number_of_constraints The maximum number of constraint to associate to the variable
+ */
XBT_PUBLIC(lmm_variable_t) lmm_variable_new(lmm_system_t sys, void *id,
double weight_value,
double bound,
int number_of_constraints);
- void lmm_variable_free(lmm_system_t sys, lmm_variable_t var);
+/**
+ * @brief Free a variable
+ *
+ * @param sys The system associated to the variable
+ * @param var The variable to free
+ */
+XBT_PUBLIC(void) lmm_variable_free(lmm_system_t sys, lmm_variable_t var);
+
+/**
+ * @brief Get the value of the variable after the last lmm solve
+ *
+ * @param var A variable
+ * @return The value of the variable
+ */
XBT_PUBLIC(double) lmm_variable_getvalue(lmm_variable_t var);
+
+/**
+ * @brief Get the maximum value of the variable (-1.0 if no maximum value)
+ *
+ * @param var A variable
+ * @return The bound of the variable
+ */
XBT_PUBLIC(double) lmm_variable_getbound(lmm_variable_t var);
+/**
+ * @brief Remove a variable from a constraint
+ *
+ * @param sys A system
+ * @param cnst A constraint
+ * @param var The variable to remove
+ */
+XBT_PUBLIC(void) lmm_shrink(lmm_system_t sys, lmm_constraint_t cnst,
+ lmm_variable_t var);
+
+/**
+ * @brief Associate a variable to a constraint with a coefficient
+ *
+ * @param sys A system
+ * @param cnst A constraint
+ * @param var A variable
+ * @param value The coefficient associated to the variable in the constraint
+ */
XBT_PUBLIC(void) lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
lmm_variable_t var, double value);
- void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
- lmm_variable_t var, double value);
- void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
- lmm_variable_t var, double value);
- lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
- lmm_variable_t var, int num);
- int lmm_get_number_of_cnst_from_var(lmm_system_t sys,
- lmm_variable_t var);
- lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
- lmm_constraint_t cnst,
- lmm_element_t * elem);
+/**
+ * @brief Add value to the coefficient between a constraint and a variable or
+ * create one
+ *
+ * @param sys A system
+ * @param cnst A constraint
+ * @param var A variable
+ * @param value The value to add to the coefficient associated to the variable in the constraint
+ */
+XBT_PUBLIC(void) lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
+ lmm_variable_t var, double value);
- lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys);
- lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
- lmm_constraint_t cnst);
+/**
+ * @brief Get the numth constraint associated to the variable
+ *
+ * @param sys The system associated to the variable (not used)
+ * @param var A variable
+ * @param num The rank of constraint we want to get
+ * @return The numth constraint
+ */
+XBT_PUBLIC(lmm_constraint_t) lmm_get_cnst_from_var(lmm_system_t sys,
+ lmm_variable_t var, int num);
+
+/**
+ * @brief Get the weigth of the numth constraint associated to the variable
+ *
+ * @param sys The system associated to the variable (not used)
+ * @param var A variable
+ * @param num The rank of constraint we want to get
+ * @return The numth constraint
+ */
+XBT_PUBLIC(double) lmm_get_cnst_weight_from_var(lmm_system_t sys, lmm_variable_t var,
+ int num);
+
+/**
+ * @brief Get the number of constraint associated to a variable
+ *
+ * @param sys The system associated to the variable (not used)
+ * @param var A variable
+ * @return The number of constraint associated to the variable
+ */
+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
+ * @details Get the first variable of the next variable of elem if elem is not NULL
+ *
+ * @param sys The system associated to the variable (not used)
+ * @param cnst A constraint
+ * @param elem A element of constraint of the constraint or NULL
+ * @return A variable associated to a constraint
+ */
+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
+ */
+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
+ *
+ * @param sys A system
+ * @param cnst An active constraint of the system
+ *
+ * @return The next active constraint
+ */
+XBT_PUBLIC(lmm_constraint_t) lmm_get_next_active_constraint(lmm_system_t sys,
+ lmm_constraint_t cnst);
+
+#ifdef HAVE_LATENCY_BOUND_TRACKING
+XBT_PUBLIC(int) lmm_is_variable_limited_by_latency(lmm_variable_t var);
+#endif
- void *lmm_constraint_id(lmm_constraint_t cnst);
- void *lmm_variable_id(lmm_variable_t var);
+/**
+ * @brief Get the data associated to a constraint
+ *
+ * @param cnst A constraint
+ * @return The data associated to the constraint
+ */
+XBT_PUBLIC(void *) lmm_constraint_id(lmm_constraint_t cnst);
- void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
- lmm_variable_t var, double value);
- void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
- double bound);
+/**
+ * @brief Get the data associated to a variable
+ *
+ * @param var A variable
+ * @return The data associated to the variable
+ */
+XBT_PUBLIC(void *) lmm_variable_id(lmm_variable_t var);
+/**
+ * @brief Update the value of element linking the constraint and the variable
+ *
+ * @param sys A system
+ * @param cnst A constraint
+ * @param var A variable
+ * @param value The new value
+ */
+XBT_PUBLIC(void) lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
+ lmm_variable_t var, double value);
+/**
+ * @brief Update the bound of a variable
+ *
+ * @param sys A system
+ * @param var A constraint
+ * @param bound The new bound
+ */
+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 weight The new weight of the variable
+ */
XBT_PUBLIC(void) lmm_update_variable_weight(lmm_system_t sys,
lmm_variable_t var,
double weight);
- double lmm_get_variable_weight(lmm_variable_t var);
+/**
+ * @brief Get the weight of a variable
+ *
+ * @param var A variable
+ * @return The weight of the variable
+ */
+XBT_PUBLIC(double) lmm_get_variable_weight(lmm_variable_t var);
+
+/**
+ * @brief Update a constraint bound
+ *
+ * @param sys A system
+ * @param cnst A constraint
+ * @param bound The new bound of the consrtaint
+ */
XBT_PUBLIC(void) lmm_update_constraint_bound(lmm_system_t sys,
lmm_constraint_t cnst,
double bound);
- int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst);
-
+/**
+ * @brief [brief description]
+ *
+ * @param sys A system
+ * @param cnst A constraint
+ * @return [description]
+ */
+XBT_PUBLIC(int) lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst);
+/**
+ * @brief Solve the lmm system
+ *
+ * @param sys The lmm system to solve
+ */
XBT_PUBLIC(void) lmm_solve(lmm_system_t sys);
XBT_PUBLIC(void) lagrange_solve(lmm_system_t sys);
*/
XBT_PUBLIC(void) lmm_set_default_protocol_function(double (*func_f)
- (lmm_variable_t var, double x),
+ (lmm_variable_t var,
+ double x),
double (*func_fp)
- (lmm_variable_t var, double x),
+ (lmm_variable_t var,
+ double x),
double (*func_fpi)
- (lmm_variable_t var, double x));
+ (lmm_variable_t var,
+ double x));
XBT_PUBLIC(double func_reno_f) (lmm_variable_t var, double x);
XBT_PUBLIC(double func_reno_fp) (lmm_variable_t var, double x);
XBT_PUBLIC(double func_vegas_fp) (lmm_variable_t var, double x);
XBT_PUBLIC(double func_vegas_fpi) (lmm_variable_t var, double x);
+/** @} */
+SG_END_DECL()
-#endif /* _SURF_MAXMIN_H */
+#endif /* _SURF_MAXMIN_H */
