-/* Copyright (c) 2004-2017. The SimGrid Team. All rights reserved. */
+/* Copyright (c) 2004-2023. 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_HPP
-#define SURF_MAXMIN_HPP
+#ifndef SIMGRID_KERNEL_LMM_MAXMIN_HPP
+#define SIMGRID_KERNEL_LMM_MAXMIN_HPP
-#include "src/internal_config.h"
-#include "src/surf/surf_interface.hpp"
-#include "surf/surf.hpp"
-#include "xbt/asserts.h"
-#include "xbt/mallocator.h"
-#include "xbt/misc.h"
-#include "xbt/swag.h"
-#include <cmath>
-#include <limits>
-#include <vector>
+#include "src/kernel/lmm/System.hpp"
-namespace simgrid {
-namespace kernel {
-namespace lmm {
+namespace simgrid::kernel::lmm {
-/** @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.
- *
- * Implementation details
- *
- * For implementation reasons, we are interested in distinguishing variables that actually participate to the
- * computation of constraints, and those who are part of the equations but are stuck to zero.
- * We call enabled variables, those which var.weight is strictly positive. Zero-weight variables are called disabled
- * variables.
- * Unfortunately this concept of enabled/disabled variables intersects with active/inactive variable.
- * Semantically, the intent is similar, but the conditions under which a variable is active is slightly more strict
- * than the conditions for it to be enabled.
- * A variable is active only if its var.value is non-zero (and, by construction, its var.weight is non-zero).
- * In general, variables remain disabled after their creation, which often models an initialization phase (e.g. first
- * packet propagating in the network). Then, it is enabled by the corresponding model. Afterwards, the max-min solver
- * (lmm_solve()) activates it when appropriate. It is possible that the variable is again disabled, e.g. to model the
- * pausing of an action.
- *
- * Concurrency limit and maximum
- *
- * We call concurrency, the number of variables that can be enabled at any time for each constraint.
- * From a model perspective, this "concurrency" often represents the number of actions that actually compete for one
- * constraint.
- * The LMM solver is able to limit the concurrency for each constraint, and to monitor its maximum value.
- *
- * One may want to limit the concurrency of constraints for essentially three reasons:
- * - Keep LMM system in a size that can be solved (it does not react very well with tens of thousands of variables per
- * constraint)
- * - Stay within parameters where the fluid model is accurate enough.
- * - Model serialization effects
- *
- * The concurrency limit can also be set to a negative value to disable concurrency limit. This can improve performance
- * slightly.
- *
- * Overall, each constraint contains three fields related to concurrency:
- * - concurrency_limit which is the limit enforced by the solver
- * - concurrency_current which is the current concurrency
- * - concurrency_maximum which is the observed maximum concurrency
- *
- * Variables also have one field related to concurrency: concurrency_share.
- * In effect, in some cases, one variable is involved multiple times (i.e. two elements) in a constraint.
- * For example, cross-traffic is modeled using 2 elements per constraint.
- * concurrency_share formally corresponds to the maximum number of elements that associate the variable and any given
- * constraint.
- */
-
-/** @{ @ingroup SURF_lmm */
-
-/**
- * @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) bottleneck_solve(lmm_system_t sys);
-
-/** Default functions associated to the chosen protocol. When using the lagrangian approach. */
-
-XBT_PUBLIC(void)
-lmm_set_default_protocol_function(double (*func_f)(lmm_variable_t var, double x),
- double (*func_fp)(lmm_variable_t var, double x),
- double (*func_fpi)(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_reno_fpi(lmm_variable_t var, double x);
-
-XBT_PUBLIC(double) func_reno2_f(lmm_variable_t var, double x);
-XBT_PUBLIC(double) func_reno2_fp(lmm_variable_t var, double x);
-XBT_PUBLIC(double) func_reno2_fpi(lmm_variable_t var, double x);
-
-XBT_PUBLIC(double) func_vegas_f(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);
-
-/**
- * @brief LMM element
- * Elements can be seen as glue between constraint objects and variable objects.
- * Basically, each variable will have a set of elements, one for each constraint where it is involved.
- * Then, it is used to list all variables involved in constraint through constraint's xxx_element_set lists, or
- * vice-versa list all constraints for a given variable.
- */
-XBT_PUBLIC_CLASS s_lmm_element_t
-{
-public:
- int get_concurrency() const;
- void decrease_concurrency();
- void increase_concurrency();
-
- void make_active();
- void make_inactive();
-
- /* hookup to constraint */
- s_xbt_swag_hookup_t enabled_element_set_hookup;
- s_xbt_swag_hookup_t disabled_element_set_hookup;
- s_xbt_swag_hookup_t active_element_set_hookup;
-
- lmm_constraint_t constraint;
- lmm_variable_t variable;
-
- // consumption_weight: impact of 1 byte or flop of your application onto the resource (in byte or flop)
- // - if CPU, then probably 1.
- // - If network, then 1 in forward direction and 0.05 backward for the ACKs
- double consumption_weight;
-};
-
-struct s_lmm_constraint_light_t {
- double remaining_over_usage;
- lmm_constraint_t cnst;
-};
-
-/**
- * @brief LMM constraint
- * Each constraint contains several partially overlapping logical sets of elements:
- * \li Disabled elements which variable's weight is zero. This variables are not at all processed by LMM, but eventually
- * the corresponding action will enable it (at least this is the idea).
- * \li Enabled elements which variable's weight is non-zero. They are utilized in some LMM functions.
- * \li Active elements which variable's weight is non-zero (i.e. it is enabled) AND its element value is non-zero.
- * LMM_solve iterates over active elements during resolution, dynamically making them active or unactive.
- */
-XBT_PUBLIC_CLASS s_lmm_constraint_t
-{
+class XBT_PUBLIC MaxMin : public System {
public:
- s_lmm_constraint_t() = default;
- s_lmm_constraint_t(void* id_value, double bound_value);
-
- /** @brief Unshare a constraint. */
- void unshare() { sharing_policy = 0; }
-
- /**
- * @brief Check if a constraint is shared (shared by default)
- * @return 1 if shared, 0 otherwise
- */
- int get_sharing_policy() const { return sharing_policy; }
-
- /**
- * @brief Get the usage of the constraint after the last lmm solve
- * @return The usage of the constraint
- */
- double get_usage() const;
- int get_variable_amount() const;
-
- /**
- * @brief Sets the concurrency limit for this constraint
- * @param concurrency_limit The concurrency limit to use for this constraint
- */
- void set_concurrency_limit(int limit)
- {
- xbt_assert(limit < 0 || concurrency_maximum <= limit,
- "New concurrency limit should be larger than observed concurrency maximum. Maybe you want to call"
- " concurrency_maximum_reset() to reset the maximum?");
- concurrency_limit = limit;
- }
-
- /**
- * @brief Gets the concurrency limit for this constraint
- * @return The concurrency limit used by this constraint
- */
- int get_concurrency_limit() const { return concurrency_limit; }
-
- /**
- * @brief Reset the concurrency maximum for a given variable (we will update the maximum to reflect constraint
- * evolution).
- */
- void reset_concurrency_maximum() { concurrency_maximum = 0; }
-
- /**
- * @brief Get the concurrency maximum for a given variable (which reflects constraint evolution).
- * @return the maximum concurrency of the constraint
- */
- int get_concurrency_maximum() const
- {
- xbt_assert(concurrency_limit < 0 || concurrency_maximum <= concurrency_limit,
- "Very bad: maximum observed concurrency is higher than limit. This is a bug of SURF, please report it.");
- return concurrency_maximum;
- }
-
- int get_concurrency_slack() const
- {
- return concurrency_limit < 0 ? std::numeric_limits<int>::max() : concurrency_limit - concurrency_current;
- }
-
- /**
- * @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 elem A element of constraint of the constraint or NULL
- * @return A variable associated to a constraint
- */
- lmm_variable_t get_variable(const_lmm_element_t* elem) const;
-
- /**
- * @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 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
- */
- lmm_variable_t get_variable_safe(const_lmm_element_t* elem, const_lmm_element_t* nextelem, int* numelem) const;
-
- /**
- * @brief Get the data associated to a constraint
- * @return The data associated to the constraint
- */
- void* get_id() const { return id; }
-
- /* hookup to system */
- s_xbt_swag_hookup_t constraint_set_hookup = {nullptr, nullptr};
- s_xbt_swag_hookup_t active_constraint_set_hookup = {nullptr, nullptr};
- s_xbt_swag_hookup_t modified_constraint_set_hookup = {nullptr, nullptr};
- s_xbt_swag_hookup_t saturated_constraint_set_hookup = {nullptr, nullptr};
- s_xbt_swag_t enabled_element_set; /* a list of lmm_element_t */
- s_xbt_swag_t disabled_element_set; /* a list of lmm_element_t */
- s_xbt_swag_t active_element_set; /* a list of lmm_element_t */
- double remaining;
- double usage;
- double bound;
- // TODO MARTIN Check maximum value across resources at the end of simulation and give a warning is more than e.g. 500
- int concurrency_current; /* The current concurrency */
- int concurrency_maximum; /* The maximum number of (enabled and disabled) variables associated to the constraint at any
- * given time (essentially for tracing)*/
-
- int sharing_policy; /* see @e_surf_link_sharing_policy_t (0: FATPIPE, 1: SHARED, 2: FULLDUPLEX) */
- int id_int;
- double lambda;
- double new_lambda;
- lmm_constraint_light_t cnst_light;
+ using System::System;
private:
- static int Global_debug_id;
- int concurrency_limit; /* The maximum number of variables that may be enabled at any time (stage variables if
- * necessary) */
- void* id;
-};
-
-/**
- * @brief LMM variable
- *
- * When something prevents us from enabling a variable, we "stage" the weight that we would have like to set, so that as
- * soon as possible we enable the variable with desired weight
- */
-XBT_PUBLIC_CLASS s_lmm_variable_t
-{
-public:
- void initialize(simgrid::surf::Action * id_value, double sharing_weight_value, double bound_value,
- int number_of_constraints, unsigned visited_value);
-
- /**
- * @brief Get the value of the variable after the last lmm solve
- * @return The value of the variable
- */
- double get_value() const { return value; }
-
- /**
- * @brief Get the maximum value of the variable (-1.0 if no maximum value)
- * @return The bound of the variable
- */
- double get_bound() const { return bound; }
-
- /**
- * @brief Set the concurrent share of the variable
- * @param concurrency_share The new concurrency share
- */
- void set_concurrency_share(short int value) { concurrency_share = 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 get_constraint(unsigned num) const { return num < cnsts.size() ? cnsts[num].constraint : nullptr; }
-
- /**
- * @brief Get the weigth of the numth constraint associated to the variable
- * @param num The rank of constraint we want to get
- * @return The numth constraint
- */
- double get_constraint_weight(unsigned num) const { return num < cnsts.size() ? cnsts[num].consumption_weight : 0.0; }
+ void do_solve() final;
+ template <class CnstList> void maxmin_solve(CnstList& cnst_list);
- /**
- * @brief Get the number of constraint associated to a variable
- * @return The number of constraint associated to the variable
- */
- int get_number_of_constraint() const { return cnsts.size(); }
+ using dyn_light_t = std::vector<int>;
- /**
- * @brief Get the data associated to a variable
- * @return The data associated to the variable
- */
- simgrid::surf::Action* get_id() const { return id; }
-
- /**
- * @brief Get the weight of a variable
- * @return The weight of the variable
- */
- double get_weight() const { return sharing_weight; }
-
- /** @brief Measure the minimum concurrency slack across all constraints where the given var is involved */
- int get_min_concurrency_slack() const;
-
- /** @brief Check if a variable can be enabled
- * Make sure to set staged_weight before, if your intent is only to check concurrency
- */
- int can_enable() const { return staged_weight > 0 && get_min_concurrency_slack() >= concurrency_share; }
-
- /* hookup to system */
- s_xbt_swag_hookup_t variable_set_hookup = {nullptr, nullptr};
- s_xbt_swag_hookup_t saturated_variable_set_hookup = {nullptr, nullptr};
-
- std::vector<s_lmm_element_t> cnsts;
-
- // sharing_weight: variable's impact on the resource during the sharing
- // if == 0, the variable is not considered by LMM
- // on CPU, actions with N threads have a sharing of N
- // on network, the actions with higher latency have a lesser sharing_weight
- double sharing_weight;
-
- double staged_weight; /* If non-zero, variable is staged for addition as soon as maxconcurrency constraints will be
- * met */
- double bound;
- double value;
- short int concurrency_share; /* The maximum number of elements that variable will add to a constraint */
- simgrid::surf::Action* id;
- int id_int;
- unsigned visited; /* used by lmm_update_modified_set */
- /* \begin{For Lagrange only} */
- double mu;
- double new_mu;
- double (*func_f)(s_lmm_variable_t * var, double x); /* (f) */
- double (*func_fp)(s_lmm_variable_t * var, double x); /* (f') */
- double (*func_fpi)(s_lmm_variable_t * var, double x); /* (f')^{-1} */
- /* \end{For Lagrange only} */
-
-private:
- static int Global_debug_id;
-};
-
-inline void s_lmm_element_t::make_active()
-{
- xbt_swag_insert_at_head(this, &constraint->active_element_set);
-}
-inline void s_lmm_element_t::make_inactive()
-{
- xbt_swag_remove(this, &constraint->active_element_set);
-}
-
-/**
- * @brief LMM system
- */
-XBT_PUBLIC_CLASS s_lmm_system_t
-{
-public:
- /**
- * @brief Create a new Linear MaxMim system
- * @param selective_update whether we should do lazy updates
- */
- explicit s_lmm_system_t(bool selective_update);
- /** @brief Free an existing Linear MaxMin system */
- ~s_lmm_system_t();
-
- /**
- * @brief Create a new Linear MaxMin constraint
- * @param id Data associated to the constraint (e.g.: a network link)
- * @param bound_value The bound value of the constraint
- */
- lmm_constraint_t constraint_new(void* id, double bound_value);
-
- /**
- * @brief Create a new Linear MaxMin variable
- * @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
- */
- lmm_variable_t variable_new(simgrid::surf::Action * id, double weight_value, double bound, int number_of_constraints);
-
- /**
- * @brief Free a variable
- * @param var The variable to free
- */
- void variable_free(lmm_variable_t var);
-
- /**
- * @brief Associate a variable to a constraint with a coefficient
- * @param cnst A constraint
- * @param var A variable
- * @param value The coefficient associated to the variable in the constraint
- */
- void expand(lmm_constraint_t cnst, lmm_variable_t var, double value);
-
- /**
- * @brief Add value to the coefficient between a constraint and a variable or create one
- * @param cnst A constraint
- * @param var A variable
- * @param value The value to add to the coefficient associated to the variable in the constraint
- */
- void expand_add(lmm_constraint_t cnst, lmm_variable_t var, double value);
-
- /**
- * @brief Update the bound of a variable
- * @param var A constraint
- * @param bound The new bound
- */
- void update_variable_bound(lmm_variable_t var, double bound);
-
- /**
- * @brief Update the weight of a variable
- * @param var A variable
- * @param weight The new weight of the variable
- */
- void update_variable_weight(lmm_variable_t var, double weight);
-
- /**
- * @brief Update a constraint bound
- * @param cnst A constraint
- * @param bound The new bound of the consrtaint
- */
- void update_constraint_bound(lmm_constraint_t cnst, double bound);
-
- /**
- * @brief [brief description]
- * @param cnst A constraint
- * @return [description]
- */
- int constraint_used(lmm_constraint_t cnst) { return xbt_swag_belongs(cnst, &active_constraint_set); }
-
- /** @brief Print the lmm system */
- void print() const;
-
- /** @brief Solve the lmm system */
- void solve();
-
-private:
- static void* variable_mallocator_new_f();
- static void variable_mallocator_free_f(void* var);
-
- void var_free(lmm_variable_t var);
- void cnst_free(lmm_constraint_t cnst);
- lmm_variable_t extract_variable() { return static_cast<lmm_variable_t>(xbt_swag_extract(&variable_set)); }
- lmm_constraint_t extract_constraint() { return static_cast<lmm_constraint_t>(xbt_swag_extract(&constraint_set)); }
- void insert_constraint(lmm_constraint_t cnst) { xbt_swag_insert(cnst, &constraint_set); }
- void remove_variable(lmm_variable_t var)
- {
- xbt_swag_remove(var, &variable_set);
- xbt_swag_remove(var, &saturated_variable_set);
- }
- void make_constraint_active(lmm_constraint_t cnst) { xbt_swag_insert(cnst, &active_constraint_set); }
- void make_constraint_inactive(lmm_constraint_t cnst)
- {
- xbt_swag_remove(cnst, &active_constraint_set);
- xbt_swag_remove(cnst, &modified_constraint_set);
- }
-
- void enable_var(lmm_variable_t var);
- void disable_var(lmm_variable_t var);
- void on_disabled_var(lmm_constraint_t cnstr);
-
- /**
- * @brief Update the value of element linking the constraint and the variable
- * @param cnst A constraint
- * @param var A variable
- * @param value The new value
- */
- void update(lmm_constraint_t cnst, lmm_variable_t var, double value);
-
- void update_modified_set(lmm_constraint_t cnst);
- void update_modified_set_rec(lmm_constraint_t cnst);
-
- /** @brief Remove all constraints of the modified_constraint_set. */
- void remove_all_modified_set();
- void check_concurrency() const;
-
-public:
- bool modified;
- s_xbt_swag_t variable_set; /* a list of lmm_variable_t */
- s_xbt_swag_t active_constraint_set; /* a list of lmm_constraint_t */
- s_xbt_swag_t saturated_variable_set; /* a list of lmm_variable_t */
- s_xbt_swag_t saturated_constraint_set; /* a list of lmm_constraint_t */
-
- simgrid::surf::ActionLmmListPtr keep_track;
-
- void (*solve_fun)(lmm_system_t self);
-
-private:
- bool selective_update_active; /* flag to update partially the system only selecting changed portions */
- unsigned visited_counter; /* used by lmm_update_modified_set and lmm_remove_modified_set to cleverly (un-)flag the
- * constraints (more details in these functions) */
- s_xbt_swag_t constraint_set; /* a list of lmm_constraint_t */
- s_xbt_swag_t modified_constraint_set; /* a list of modified lmm_constraint_t */
- xbt_mallocator_t variable_mallocator;
+ std::vector<ConstraintLight> cnst_light_vec;
+ dyn_light_t saturated_constraints;
};
-extern XBT_PRIVATE double (*func_f_def)(lmm_variable_t, double);
-extern XBT_PRIVATE double (*func_fp_def)(lmm_variable_t, double);
-extern XBT_PRIVATE double (*func_fpi_def)(lmm_variable_t, double);
-
-/** @} */
-}
-}
-}
+} // namespace simgrid::kernel::lmm
#endif
