1 /* Copyright (c) 2004-2021. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/kernel/lmm/maxmin.hpp"
7 #include <boost/core/demangle.hpp>
10 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf, "Logging specific to SURF (maxmin)");
12 double sg_maxmin_precision = 1E-5; /* Change this with --cfg=maxmin/precision:VALUE */
13 double sg_surf_precision = 1E-9; /* Change this with --cfg=surf/precision:VALUE */
14 int sg_concurrency_limit = -1; /* Change this with --cfg=maxmin/concurrency-limit:VALUE */
20 using dyn_light_t = std::vector<int>;
22 int Variable::next_rank_ = 1;
23 int Constraint::next_rank_ = 1;
25 int Element::get_concurrency() const
27 // Ignore element with weight less than one (e.g. cross-traffic)
28 return (consumption_weight >= 1) ? 1 : 0;
29 // There are other alternatives, but they will change the behavior of the model..
30 // So do not use it unless you want to make a new model.
31 // If you do, remember to change the variables concurrency share to reflect it.
32 // Potential examples are:
33 // return (elem->weight>0)?1:0;//Include element as soon as weight is non-zero
34 // return (int)ceil(elem->weight);//Include element as the rounded-up integer value of the element weight
37 void Element::decrease_concurrency()
39 xbt_assert(constraint->concurrency_current_ >= get_concurrency());
40 constraint->concurrency_current_ -= get_concurrency();
43 void Element::increase_concurrency()
45 constraint->concurrency_current_ += get_concurrency();
47 if (constraint->concurrency_current_ > constraint->concurrency_maximum_)
48 constraint->concurrency_maximum_ = constraint->concurrency_current_;
50 xbt_assert(constraint->get_concurrency_limit() < 0 ||
51 constraint->concurrency_current_ <= constraint->get_concurrency_limit(),
52 "Concurrency limit overflow!");
55 void System::check_concurrency() const
57 // These checks are very expensive, so do them only if we want to debug SURF LMM
58 if (not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug))
61 for (Constraint const& cnst : constraint_set) {
63 for (Element const& elem : cnst.enabled_element_set_) {
64 xbt_assert(elem.variable->sharing_penalty_ > 0);
65 concurrency += elem.get_concurrency();
68 for (Element const& elem : cnst.disabled_element_set_) {
69 // We should have staged variables only if concurrency is reached in some constraint
70 xbt_assert(cnst.get_concurrency_limit() < 0 || elem.variable->staged_penalty_ == 0 ||
71 elem.variable->get_min_concurrency_slack() < elem.variable->concurrency_share_,
72 "should not have staged variable!");
75 xbt_assert(cnst.get_concurrency_limit() < 0 || cnst.get_concurrency_limit() >= concurrency,
76 "concurrency check failed!");
77 xbt_assert(cnst.concurrency_current_ == concurrency, "concurrency_current is out-of-date!");
80 // Check that for each variable, all corresponding elements are in the same state (i.e. same element sets)
81 for (Variable const& var : variable_set) {
82 if (var.cnsts_.empty())
85 const Element& elem = var.cnsts_[0];
86 bool belong_to_enabled = elem.enabled_element_set_hook.is_linked();
87 bool belong_to_disabled = elem.disabled_element_set_hook.is_linked();
88 bool belong_to_active = elem.active_element_set_hook.is_linked();
90 for (Element const& elem2 : var.cnsts_) {
91 xbt_assert(belong_to_enabled == elem2.enabled_element_set_hook.is_linked(),
92 "Variable inconsistency (1): enabled_element_set");
93 xbt_assert(belong_to_disabled == elem2.disabled_element_set_hook.is_linked(),
94 "Variable inconsistency (2): disabled_element_set");
95 xbt_assert(belong_to_active == elem2.active_element_set_hook.is_linked(),
96 "Variable inconsistency (3): active_element_set");
101 void System::var_free(Variable* var)
103 XBT_IN("(sys=%p, var=%p)", this, var);
106 // TODOLATER Can do better than that by leaving only the variable in only one enabled_element_set, call
107 // update_modified_set, and then remove it..
108 if (not var->cnsts_.empty())
109 update_modified_set(var->cnsts_[0].constraint);
111 for (Element& elem : var->cnsts_) {
112 if (var->sharing_penalty_ > 0)
113 elem.decrease_concurrency();
114 if (elem.enabled_element_set_hook.is_linked())
115 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set_, elem);
116 if (elem.disabled_element_set_hook.is_linked())
117 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set_, elem);
118 if (elem.active_element_set_hook.is_linked())
119 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set_, elem);
120 int nelements = elem.constraint->enabled_element_set_.size() + elem.constraint->disabled_element_set_.size();
122 make_constraint_inactive(elem.constraint);
124 on_disabled_var(elem.constraint);
131 xbt_mallocator_release(variable_mallocator_, var);
135 System::System(bool selective_update) : selective_update_active(selective_update)
137 XBT_DEBUG("Setting selective_update_active flag to %d", selective_update_active);
139 if (selective_update)
140 modified_set_ = std::make_unique<kernel::resource::Action::ModifiedSet>();
145 while (Variable* var = extract_variable()) {
146 std::string demangled = boost::core::demangle(var->id_ ? typeid(*var->id_).name() : "(unidentified)");
147 XBT_WARN("Probable bug: a %s variable (#%d) not removed before the LMM system destruction.", demangled.c_str(),
151 while (Constraint* cnst = extract_constraint())
154 xbt_mallocator_free(variable_mallocator_);
157 void System::cnst_free(Constraint* cnst)
159 make_constraint_inactive(cnst);
163 Constraint::Constraint(resource::Resource* id_value, double bound_value) : bound_(bound_value), id_(id_value)
165 rank_ = next_rank_++;
168 Constraint* System::constraint_new(resource::Resource* id, double bound_value)
170 auto* cnst = new Constraint(id, bound_value);
171 insert_constraint(cnst);
175 void* System::variable_mallocator_new_f()
180 void System::variable_mallocator_free_f(void* var)
182 delete static_cast<Variable*>(var);
185 Variable* System::variable_new(resource::Action* id, double sharing_penalty, double bound, size_t number_of_constraints)
187 XBT_IN("(sys=%p, id=%p, penalty=%f, bound=%f, num_cons =%zu)", this, id, sharing_penalty, bound,
188 number_of_constraints);
190 auto* var = static_cast<Variable*>(xbt_mallocator_get(variable_mallocator_));
191 var->initialize(id, sharing_penalty, bound, number_of_constraints, visited_counter_ - 1);
192 if (sharing_penalty > 0)
193 variable_set.push_front(*var);
195 variable_set.push_back(*var);
197 XBT_OUT(" returns %p", var);
201 void System::variable_free(Variable* var)
203 remove_variable(var);
207 void System::variable_free_all()
209 while (Variable* var = extract_variable())
213 void System::expand(Constraint* cnst, Variable* var, double consumption_weight)
217 // Check if this variable already has an active element in this constraint
218 // If it does, subtract it from the required slack
219 int current_share = 0;
220 if (var->concurrency_share_ > 1) {
221 for (const Element& elem : var->cnsts_) {
222 if (elem.constraint == cnst && elem.enabled_element_set_hook.is_linked())
223 current_share += elem.get_concurrency();
227 // Check if we need to disable the variable
228 if (var->sharing_penalty_ > 0 && var->concurrency_share_ - current_share > cnst->get_concurrency_slack()) {
229 double penalty = var->sharing_penalty_;
231 for (Element const& elem : var->cnsts_)
232 on_disabled_var(elem.constraint);
233 consumption_weight = 0;
234 var->staged_penalty_ = penalty;
235 xbt_assert(not var->sharing_penalty_);
238 xbt_assert(var->cnsts_.size() < var->cnsts_.capacity(), "Too much constraints");
240 var->cnsts_.emplace_back();
241 Element& elem = var->cnsts_.back();
243 elem.consumption_weight = consumption_weight;
244 elem.constraint = cnst;
247 if (var->sharing_penalty_ != 0.0) {
248 elem.constraint->enabled_element_set_.push_front(elem);
249 elem.increase_concurrency();
251 elem.constraint->disabled_element_set_.push_back(elem);
253 if (not selective_update_active) {
254 make_constraint_active(cnst);
255 } else if (elem.consumption_weight > 0 || var->sharing_penalty_ > 0) {
256 make_constraint_active(cnst);
257 update_modified_set(cnst);
258 // TODOLATER: Why do we need this second call?
259 if (var->cnsts_.size() > 1)
260 update_modified_set(var->cnsts_[0].constraint);
266 void System::expand_add(Constraint* cnst, Variable* var, double value)
272 // BEWARE: In case you have multiple elements in one constraint, this will always add value to the first element.
274 std::find_if(begin(var->cnsts_), end(var->cnsts_), [&cnst](Element const& x) { return x.constraint == cnst; });
275 if (elem_it != end(var->cnsts_)) {
276 Element& elem = *elem_it;
277 if (var->sharing_penalty_ != 0.0)
278 elem.decrease_concurrency();
280 if (cnst->sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE)
281 elem.consumption_weight += value;
283 elem.consumption_weight = std::max(elem.consumption_weight, value);
285 // We need to check that increasing value of the element does not cross the concurrency limit
286 if (var->sharing_penalty_ != 0.0) {
287 if (cnst->get_concurrency_slack() < elem.get_concurrency()) {
288 double penalty = var->sharing_penalty_;
290 for (Element const& elem2 : var->cnsts_)
291 on_disabled_var(elem2.constraint);
292 var->staged_penalty_ = penalty;
293 xbt_assert(not var->sharing_penalty_);
295 elem.increase_concurrency();
297 update_modified_set(cnst);
299 expand(cnst, var, value);
304 Variable* Constraint::get_variable(const Element** elem) const
306 if (*elem == nullptr) {
307 // That is the first call, pick the first element among enabled_element_set (or disabled_element_set if
308 // enabled_element_set is empty)
309 if (not enabled_element_set_.empty())
310 *elem = &enabled_element_set_.front();
311 else if (not disabled_element_set_.empty())
312 *elem = &disabled_element_set_.front();
316 // elem is not null, so we carry on
317 if ((*elem)->enabled_element_set_hook.is_linked()) {
318 // Look at enabled_element_set, and jump to disabled_element_set when finished
319 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
320 if (iter != std::end(enabled_element_set_))
322 else if (not disabled_element_set_.empty())
323 *elem = &disabled_element_set_.front();
327 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
328 *elem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
332 return (*elem)->variable;
337 // if we modify the list between calls, normal version may loop forever
338 // this safe version ensures that we browse the list elements only once
339 Variable* Constraint::get_variable_safe(const Element** elem, const Element** nextelem, int* numelem) const
341 if (*elem == nullptr) {
342 *numelem = enabled_element_set_.size() + disabled_element_set_.size() - 1;
343 if (not enabled_element_set_.empty())
344 *elem = &enabled_element_set_.front();
345 else if (not disabled_element_set_.empty())
346 *elem = &disabled_element_set_.front();
357 // elem is not null, so we carry on
358 if ((*elem)->enabled_element_set_hook.is_linked()) {
359 // Look at enabled_element_set, and jump to disabled_element_set when finished
360 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
361 if (iter != std::end(enabled_element_set_))
363 else if (not disabled_element_set_.empty())
364 *nextelem = &disabled_element_set_.front();
368 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
369 *nextelem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
371 return (*elem)->variable;
376 static inline void saturated_constraints_update(double usage, int cnst_light_num, dyn_light_t& saturated_constraints,
379 xbt_assert(usage > 0, "Impossible");
381 if (*min_usage < 0 || *min_usage > usage) {
383 XBT_HERE(" min_usage=%f (cnst->remaining / cnst->usage =%f)", *min_usage, usage);
384 saturated_constraints.assign(1, cnst_light_num);
385 } else if (*min_usage == usage) {
386 saturated_constraints.emplace_back(cnst_light_num);
390 static inline void saturated_variable_set_update(const ConstraintLight* cnst_light_tab,
391 const dyn_light_t& saturated_constraints, System* sys)
393 /* Add active variables (i.e. variables that need to be set) from the set of constraints to saturate
395 for (int const& saturated_cnst : saturated_constraints) {
396 const ConstraintLight& cnst = cnst_light_tab[saturated_cnst];
397 for (Element const& elem : cnst.cnst->active_element_set_) {
398 xbt_assert(elem.variable->sharing_penalty_ > 0); // All elements of active_element_set should be active
399 if (elem.consumption_weight > 0 && not elem.variable->saturated_variable_set_hook_.is_linked())
400 sys->saturated_variable_set.push_back(*elem.variable);
405 template <class ElemList>
406 static void format_element_list(const ElemList& elem_list, s4u::Link::SharingPolicy sharing_policy, double& sum,
409 for (Element const& elem : elem_list) {
410 buf += std::to_string(elem.consumption_weight) + ".'" + std::to_string(elem.variable->rank_) + "'(" +
411 std::to_string(elem.variable->value_) + ")" +
412 (sharing_policy != s4u::Link::SharingPolicy::FATPIPE ? " + " : " , ");
413 if (sharing_policy != s4u::Link::SharingPolicy::FATPIPE)
414 sum += elem.consumption_weight * elem.variable->value_;
416 sum = std::max(sum, elem.consumption_weight * elem.variable->value_);
420 void System::print() const
422 std::string buf = "MAX-MIN ( ";
424 /* Printing Objective */
425 for (Variable const& var : variable_set)
426 buf += "'" + std::to_string(var.rank_) + "'(" + std::to_string(var.sharing_penalty_) + ") ";
428 XBT_DEBUG("%20s", buf.c_str());
431 XBT_DEBUG("Constraints");
432 /* Printing Constraints */
433 for (Constraint const& cnst : active_constraint_set) {
435 // Show the enabled variables
437 buf += cnst.sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE ? "(" : "max(";
438 format_element_list(cnst.enabled_element_set_, cnst.sharing_policy_, sum, buf);
439 // TODO: Adding disabled elements only for test compatibility, but do we really want them to be printed?
440 format_element_list(cnst.disabled_element_set_, cnst.sharing_policy_, sum, buf);
442 buf += "0) <= " + std::to_string(cnst.bound_) + " ('" + std::to_string(cnst.rank_) + "')";
444 if (cnst.sharing_policy_ == s4u::Link::SharingPolicy::FATPIPE) {
445 buf += " [MAX-Constraint]";
447 XBT_DEBUG("%s", buf.c_str());
449 xbt_assert(not double_positive(sum - cnst.bound_, cnst.bound_ * sg_maxmin_precision),
450 "Incorrect value (%f is not smaller than %f): %g", sum, cnst.bound_, sum - cnst.bound_);
453 XBT_DEBUG("Variables");
454 /* Printing Result */
455 for (Variable const& var : variable_set) {
456 if (var.bound_ > 0) {
457 XBT_DEBUG("'%d'(%f) : %f (<=%f)", var.rank_, var.sharing_penalty_, var.value_, var.bound_);
458 xbt_assert(not double_positive(var.value_ - var.bound_, var.bound_ * sg_maxmin_precision),
459 "Incorrect value (%f is not smaller than %f", var.value_, var.bound_);
461 XBT_DEBUG("'%d'(%f) : %f", var.rank_, var.sharing_penalty_, var.value_);
466 void System::lmm_solve()
469 XBT_IN("(sys=%p)", this);
470 /* Compute Usage and store the variables that reach the maximum. If selective_update_active is true, only
471 * constraints that changed are considered. Otherwise all constraints with active actions are considered.
473 if (selective_update_active)
474 lmm_solve(modified_constraint_set);
476 lmm_solve(active_constraint_set);
481 template <class CnstList> void System::lmm_solve(CnstList& cnst_list)
483 double min_usage = -1;
484 double min_bound = -1;
486 XBT_DEBUG("Active constraints : %zu", cnst_list.size());
487 cnst_light_vec.reserve(cnst_list.size());
488 ConstraintLight* cnst_light_tab = cnst_light_vec.data();
489 int cnst_light_num = 0;
491 for (Constraint& cnst : cnst_list) {
492 /* INIT: Collect constraints that actually need to be saturated (i.e remaining and usage are strictly positive)
493 * into cnst_light_tab. */
494 cnst.remaining_ = cnst.bound_;
495 if (not double_positive(cnst.remaining_, cnst.bound_ * sg_maxmin_precision))
498 for (Element& elem : cnst.enabled_element_set_) {
499 xbt_assert(elem.variable->sharing_penalty_ > 0.0);
500 elem.variable->value_ = 0.0;
501 if (elem.consumption_weight > 0) {
502 if (cnst.sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE)
503 cnst.usage_ += elem.consumption_weight / elem.variable->sharing_penalty_;
504 else if (cnst.usage_ < elem.consumption_weight / elem.variable->sharing_penalty_)
505 cnst.usage_ = elem.consumption_weight / elem.variable->sharing_penalty_;
508 resource::Action* action = elem.variable->id_;
509 if (modified_set_ && not action->is_within_modified_set())
510 modified_set_->push_back(*action);
513 XBT_DEBUG("Constraint '%d' usage: %f remaining: %f concurrency: %i<=%i<=%i", cnst.rank_, cnst.usage_,
514 cnst.remaining_, cnst.concurrency_current_, cnst.concurrency_maximum_, cnst.get_concurrency_limit());
515 /* Saturated constraints update */
517 if (cnst.usage_ > 0) {
518 cnst_light_tab[cnst_light_num].cnst = &cnst;
519 cnst.cnst_light_ = &cnst_light_tab[cnst_light_num];
520 cnst_light_tab[cnst_light_num].remaining_over_usage = cnst.remaining_ / cnst.usage_;
521 saturated_constraints_update(cnst_light_tab[cnst_light_num].remaining_over_usage, cnst_light_num,
522 saturated_constraints, &min_usage);
523 xbt_assert(not cnst.active_element_set_.empty(),
524 "There is no sense adding a constraint that has no active element!");
529 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
531 /* Saturated variables update */
533 /* Fix the variables that have to be */
534 auto& var_list = saturated_variable_set;
535 for (Variable const& var : var_list) {
536 if (var.sharing_penalty_ <= 0.0)
538 /* First check if some of these variables could reach their upper bound and update min_bound accordingly. */
539 XBT_DEBUG("var=%d, var.bound=%f, var.penalty=%f, min_usage=%f, var.bound*var.penalty=%f", var.rank_, var.bound_,
540 var.sharing_penalty_, min_usage, var.bound_ * var.sharing_penalty_);
541 if ((var.bound_ > 0) && (var.bound_ * var.sharing_penalty_ < min_usage)) {
543 min_bound = var.bound_ * var.sharing_penalty_;
545 min_bound = std::min(min_bound, (var.bound_ * var.sharing_penalty_));
546 XBT_DEBUG("Updated min_bound=%f", min_bound);
550 while (not var_list.empty()) {
551 Variable& var = var_list.front();
553 // If no variable could reach its bound, deal iteratively the constraints usage ( at worst one constraint is
554 // saturated at each cycle)
555 var.value_ = min_usage / var.sharing_penalty_;
556 XBT_DEBUG("Setting var (%d) value to %f\n", var.rank_, var.value_);
558 // If there exist a variable that can reach its bound, only update it (and other with the same bound) for now.
559 if (double_equals(min_bound, var.bound_ * var.sharing_penalty_, sg_maxmin_precision)) {
560 var.value_ = var.bound_;
561 XBT_DEBUG("Setting %p (%d) value to %f\n", &var, var.rank_, var.value_);
563 // Variables which bound is different are not considered for this cycle, but they will be afterwards.
564 XBT_DEBUG("Do not consider %p (%d) \n", &var, var.rank_);
565 var_list.pop_front();
569 XBT_DEBUG("Min usage: %f, Var(%d).penalty: %f, Var(%d).value: %f ", min_usage, var.rank_, var.sharing_penalty_,
570 var.rank_, var.value_);
572 /* Update the usage of constraints where this variable is involved */
573 for (Element& elem : var.cnsts_) {
574 Constraint* cnst = elem.constraint;
575 if (cnst->sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE) {
576 // Remember: shared constraints require that sum(elem.value * var.value) < cnst->bound
577 double_update(&(cnst->remaining_), elem.consumption_weight * var.value_, cnst->bound_ * sg_maxmin_precision);
578 double_update(&(cnst->usage_), elem.consumption_weight / var.sharing_penalty_, sg_maxmin_precision);
579 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
580 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
581 not double_positive(cnst->remaining_, cnst->bound_ * sg_maxmin_precision)) {
582 if (cnst->cnst_light_) {
583 int index = (cnst->cnst_light_ - cnst_light_tab);
584 XBT_DEBUG("index: %d \t cnst_light_num: %d \t || usage: %f remaining: %f bound: %f ", index,
585 cnst_light_num, cnst->usage_, cnst->remaining_, cnst->bound_);
586 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
587 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
589 cnst->cnst_light_ = nullptr;
592 if (cnst->cnst_light_) {
593 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
596 elem.make_inactive();
598 // Remember: non-shared constraints only require that max(elem.value * var.value) < cnst->bound
600 elem.make_inactive();
601 for (const Element& elem2 : cnst->enabled_element_set_) {
602 xbt_assert(elem2.variable->sharing_penalty_ > 0);
603 if (elem2.variable->value_ > 0)
605 if (elem2.consumption_weight > 0)
606 cnst->usage_ = std::max(cnst->usage_, elem2.consumption_weight / elem2.variable->sharing_penalty_);
608 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
609 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
610 not double_positive(cnst->remaining_, cnst->bound_ * sg_maxmin_precision)) {
611 if (cnst->cnst_light_) {
612 int index = (cnst->cnst_light_ - cnst_light_tab);
613 XBT_DEBUG("index: %d \t cnst_light_num: %d \t || \t cnst: %p \t cnst->cnst_light: %p "
614 "\t cnst_light_tab: %p usage: %f remaining: %f bound: %f ",
615 index, cnst_light_num, cnst, cnst->cnst_light_, cnst_light_tab, cnst->usage_, cnst->remaining_,
617 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
618 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
620 cnst->cnst_light_ = nullptr;
623 if (cnst->cnst_light_) {
624 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
625 xbt_assert(not cnst->active_element_set_.empty(),
626 "Should not keep a maximum constraint that has no active"
627 " element! You want to check the maxmin precision and possible rounding effects.");
632 var_list.pop_front();
635 /* Find out which variables reach the maximum */
638 saturated_constraints.clear();
639 for (int pos = 0; pos < cnst_light_num; pos++) {
640 xbt_assert(not cnst_light_tab[pos].cnst->active_element_set_.empty(),
641 "Cannot saturate more a constraint that has"
642 " no active element! You may want to change the maxmin precision (--cfg=maxmin/precision:<new_value>)"
643 " because of possible rounding effects.\n\tFor the record, the usage of this constraint is %g while "
644 "the maxmin precision to which it is compared is %g.\n\tThe usage of the previous constraint is %g.",
645 cnst_light_tab[pos].cnst->usage_, sg_maxmin_precision, cnst_light_tab[pos - 1].cnst->usage_);
646 saturated_constraints_update(cnst_light_tab[pos].remaining_over_usage, pos, saturated_constraints, &min_usage);
649 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
650 } while (cnst_light_num > 0);
653 if (selective_update_active)
654 remove_all_modified_set();
656 if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
663 /** @brief Attribute the value bound to var->bound.
665 * @param var the Variable*
666 * @param bound the new bound to associate with var
668 * Makes var->bound equal to bound. Whenever this function is called a change is signed in the system. To
669 * avoid false system changing detection it is a good idea to test (bound != 0) before calling it.
671 void System::update_variable_bound(Variable* var, double bound)
676 if (not var->cnsts_.empty())
677 update_modified_set(var->cnsts_[0].constraint);
680 void Variable::initialize(resource::Action* id_value, double sharing_penalty, double bound_value,
681 int number_of_constraints, unsigned visited_value)
684 rank_ = next_rank_++;
685 cnsts_.reserve(number_of_constraints);
686 sharing_penalty_ = sharing_penalty;
687 staged_penalty_ = 0.0;
688 bound_ = bound_value;
689 concurrency_share_ = 1;
691 visited_ = visited_value;
694 xbt_assert(not variable_set_hook_.is_linked());
695 xbt_assert(not saturated_variable_set_hook_.is_linked());
698 int Variable::get_min_concurrency_slack() const
700 int minslack = std::numeric_limits<int>::max();
701 for (Element const& elem : cnsts_) {
702 int slack = elem.constraint->get_concurrency_slack();
703 if (slack < minslack) {
704 // This is only an optimization, to avoid looking at more constraints when slack is already zero
713 // Small remark: In this implementation of System::enable_var() and System::disable_var(), we will meet multiple times
714 // with var when running System::update_modified_set().
715 // A priori not a big performance issue, but we might do better by calling System::update_modified_set() within the for
716 // loops (after doing the first for enabling==1, and before doing the last for disabling==1)
717 void System::enable_var(Variable* var)
719 xbt_assert(not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug) || var->can_enable());
721 var->sharing_penalty_ = var->staged_penalty_;
722 var->staged_penalty_ = 0;
724 // Enabling the variable, move var to list head. Subtlety is: here, we need to call update_modified_set AFTER
725 // moving at least one element of var.
727 simgrid::xbt::intrusive_erase(variable_set, *var);
728 variable_set.push_front(*var);
729 for (Element& elem : var->cnsts_) {
730 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set_, elem);
731 elem.constraint->enabled_element_set_.push_front(elem);
732 elem.increase_concurrency();
734 if (not var->cnsts_.empty())
735 update_modified_set(var->cnsts_[0].constraint);
737 // When used within on_disabled_var, we would get an assertion fail, because transiently there can be variables
738 // that are staged and could be activated.
739 // Anyway, caller functions all call check_concurrency() in the end.
742 void System::disable_var(Variable* var)
744 xbt_assert(not var->staged_penalty_, "Staged penalty should have been cleared");
745 // Disabling the variable, move to var to list tail. Subtlety is: here, we need to call update_modified_set
746 // BEFORE moving the last element of var.
747 simgrid::xbt::intrusive_erase(variable_set, *var);
748 variable_set.push_back(*var);
749 if (not var->cnsts_.empty())
750 update_modified_set(var->cnsts_[0].constraint);
751 for (Element& elem : var->cnsts_) {
752 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set_, elem);
753 elem.constraint->disabled_element_set_.push_back(elem);
754 if (elem.active_element_set_hook.is_linked())
755 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set_, elem);
756 elem.decrease_concurrency();
759 var->sharing_penalty_ = 0.0;
760 var->staged_penalty_ = 0.0;
765 /* /brief Find variables that can be enabled and enable them.
767 * Assuming that the variable has already been removed from non-zero penalties
768 * Can we find a staged variable to add?
769 * If yes, check that none of the constraints that this variable is involved in is at the limit of its concurrency
770 * And then add it to enabled variables
772 void System::on_disabled_var(Constraint* cnstr)
774 if (cnstr->get_concurrency_limit() < 0)
777 int numelem = cnstr->disabled_element_set_.size();
781 Element* elem = &cnstr->disabled_element_set_.front();
783 // Cannot use foreach loop, because System::enable_var() will modify disabled_element_set.. within the loop
784 while (numelem-- && elem) {
786 if (elem->disabled_element_set_hook.is_linked()) {
787 auto iter = std::next(cnstr->disabled_element_set_.iterator_to(*elem));
788 nextelem = iter != std::end(cnstr->disabled_element_set_) ? &*iter : nullptr;
793 if (elem->variable->staged_penalty_ > 0 && elem->variable->can_enable()) {
794 // Found a staged variable
795 // TODOLATER: Add random timing function to model reservation protocol fuzziness? Then how to make sure that
796 // staged variables will eventually be called?
797 enable_var(elem->variable);
800 xbt_assert(cnstr->concurrency_current_ <= cnstr->get_concurrency_limit(), "Concurrency overflow!");
801 if (cnstr->concurrency_current_ == cnstr->get_concurrency_limit())
807 // We could get an assertion fail, because transiently there can be variables that are staged and could be activated.
808 // And we need to go through all constraints of the disabled var before getting back a coherent state.
809 // Anyway, caller functions all call check_concurrency() in the end.
812 /** @brief update the penalty of a variable (disable it by passing 0 as a penalty) */
813 void System::update_variable_penalty(Variable* var, double penalty)
815 xbt_assert(penalty >= 0, "Variable penalty should not be negative!");
817 if (penalty == var->sharing_penalty_)
820 bool enabling_var = (penalty > 0 && var->sharing_penalty_ <= 0);
821 bool disabling_var = (penalty <= 0 && var->sharing_penalty_ > 0);
823 XBT_IN("(sys=%p, var=%p, penalty=%f)", this, var, penalty);
827 // Are we enabling this variable?
829 var->staged_penalty_ = penalty;
830 int minslack = var->get_min_concurrency_slack();
831 if (minslack < var->concurrency_share_) {
832 XBT_DEBUG("Staging var (instead of enabling) because min concurrency slack %i, with penalty %f and concurrency"
834 minslack, penalty, var->concurrency_share_);
837 XBT_DEBUG("Enabling var with min concurrency slack %i", minslack);
839 } else if (disabling_var) {
842 var->sharing_penalty_ = penalty;
850 void System::update_constraint_bound(Constraint* cnst, double bound)
853 update_modified_set(cnst);
854 cnst->bound_ = bound;
857 /** @brief Update the constraint set propagating recursively to other constraints so the system should not be entirely
860 * @param cnst the Constraint* affected by the change
862 * A recursive algorithm to optimize the system recalculation selecting only constraints that have changed. Each
863 * constraint change is propagated to the list of constraints for each variable.
865 void System::update_modified_set_rec(const Constraint* cnst)
867 for (Element const& elem : cnst->enabled_element_set_) {
868 Variable* var = elem.variable;
869 for (Element const& elem2 : var->cnsts_) {
870 if (var->visited_ == visited_counter_)
872 if (elem2.constraint != cnst && not elem2.constraint->modified_constraint_set_hook_.is_linked()) {
873 modified_constraint_set.push_back(*elem2.constraint);
874 update_modified_set_rec(elem2.constraint);
877 // var will be ignored in later visits as long as sys->visited_counter does not move
878 var->visited_ = visited_counter_;
882 void System::update_modified_set(Constraint* cnst)
884 /* nothing to do if selective update isn't active */
885 if (selective_update_active && not cnst->modified_constraint_set_hook_.is_linked()) {
886 modified_constraint_set.push_back(*cnst);
887 update_modified_set_rec(cnst);
891 void System::remove_all_modified_set()
893 // We cleverly un-flag all variables just by incrementing visited_counter
894 // In effect, the var->visited value will no more be equal to visited counter
895 // To be clean, when visited counter has wrapped around, we force these var->visited values so that variables that
896 // were in the modified a long long time ago are not wrongly skipped here, which would lead to very nasty bugs
897 // (i.e. not readily reproducible, and requiring a lot of run time before happening).
898 if (++visited_counter_ == 1) {
899 /* the counter wrapped around, reset each variable->visited */
900 for (Variable& var : variable_set)
903 modified_constraint_set.clear();
907 * Returns resource load (in flop per second, or byte per second, or similar)
909 * If the resource is shared (the default case), the load is sum of resource usage made by
910 * every variables located on this resource.
912 * If the resource is not shared (ie in FATPIPE mode), then the load is the max (not the sum)
913 * of all resource usages located on this resource.
915 double Constraint::get_usage() const
918 if (sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE) {
919 for (Element const& elem : enabled_element_set_)
920 if (elem.consumption_weight > 0)
921 result += elem.consumption_weight * elem.variable->value_;
923 for (Element const& elem : enabled_element_set_)
924 if (elem.consumption_weight > 0)
925 result = std::max(result, elem.consumption_weight * elem.variable->value_);
930 int Constraint::get_variable_amount() const
932 return static_cast<int>(std::count_if(std::begin(enabled_element_set_), std::end(enabled_element_set_),
933 [](const Element& elem) { return elem.consumption_weight > 0; }));
937 } // namespace kernel
938 } // namespace simgrid