X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/3735eb9d0e10ba6574aa0a59935d7dfe09b1658e..0871bc3c784492051d51cc378726b18a4c77046e:/src/include/surf/maxmin.h diff --git a/src/include/surf/maxmin.h b/src/include/surf/maxmin.h index fa6295b523..7f58d7c906 100644 --- a/src/include/surf/maxmin.h +++ b/src/include/surf/maxmin.h @@ -17,7 +17,37 @@ * @details * A linear maxmin solver to resolves inequations systems. * - * A system is composed of variables, constraints and elements linking them. + * Most SimGrid model rely on a "fluid/steady-state" modeling that + * samount to share 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) @@ -56,22 +86,23 @@ */ extern double sg_maxmin_precision; -#define MAXMIN_PRECISION sg_maxmin_precision -static XBT_INLINE void double_update(double *variable, double value) +extern double sg_surf_precision; + +static XBT_INLINE void double_update(double *variable, double value, double precision) { *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() @@ -107,7 +138,7 @@ XBT_PUBLIC(lmm_constraint_t) lmm_constraint_new(lmm_system_t sys, void *id, * * @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) @@ -115,7 +146,7 @@ void lmm_constraint_shared(lmm_constraint_t cnst); * @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_is_shared(lmm_constraint_t cnst); /** * @brief Free a constraint @@ -123,7 +154,7 @@ int lmm_constraint_is_shared(lmm_constraint_t cnst); * @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 @@ -131,7 +162,7 @@ void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst); * @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 @@ -200,20 +231,9 @@ XBT_PUBLIC(void) lmm_expand(lmm_system_t sys, lmm_constraint_t cnst, * @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 * @@ -222,7 +242,7 @@ void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst, * @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); /** @@ -233,7 +253,7 @@ lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys, * @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); /** @@ -243,7 +263,7 @@ double lmm_get_cnst_weight_from_var(lmm_system_t sys, lmm_variable_t var, * @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 @@ -254,7 +274,7 @@ int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var); * @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); @@ -264,7 +284,7 @@ lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys, * @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 @@ -274,7 +294,7 @@ lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys); * * @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 @@ -287,7 +307,7 @@ XBT_PUBLIC(int) lmm_is_variable_limited_by_latency(lmm_variable_t var); * @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 @@ -295,7 +315,7 @@ void *lmm_constraint_id(lmm_constraint_t cnst); * @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 @@ -305,7 +325,7 @@ void *lmm_variable_id(lmm_variable_t var); * @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); /** @@ -315,14 +335,14 @@ void lmm_update(lmm_system_t sys, lmm_constraint_t cnst, * @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, @@ -335,7 +355,7 @@ 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 @@ -355,7 +375,7 @@ XBT_PUBLIC(void) lmm_update_constraint_bound(lmm_system_t sys, * @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