1 /* Copyright (c) 2004-2020. 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 "xbt/backtrace.hpp"
9 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf, "Logging specific to SURF (maxmin)");
11 double sg_maxmin_precision = 1E-5; /* Change this with --cfg=maxmin/precision:VALUE */
12 double sg_surf_precision = 1E-9; /* Change this with --cfg=surf/precision:VALUE */
13 int sg_concurrency_limit = -1; /* Change this with --cfg=maxmin/concurrency-limit:VALUE */
19 typedef std::vector<int> dyn_light_t;
21 int Variable::next_rank_ = 1;
22 int Constraint::next_rank_ = 1;
24 System* make_new_maxmin_system(bool selective_update)
26 return new System(selective_update);
29 int Element::get_concurrency() const
31 // Ignore element with weight less than one (e.g. cross-traffic)
32 return (consumption_weight >= 1) ? 1 : 0;
33 // There are other alternatives, but they will change the behavior of the model..
34 // So do not use it unless you want to make a new model.
35 // If you do, remember to change the variables concurrency share to reflect it.
36 // Potential examples are:
37 // return (elem->weight>0)?1:0;//Include element as soon as weight is non-zero
38 // return (int)ceil(elem->weight);//Include element as the rounded-up integer value of the element weight
41 void Element::decrease_concurrency()
43 xbt_assert(constraint->concurrency_current_ >= get_concurrency());
44 constraint->concurrency_current_ -= get_concurrency();
47 void Element::increase_concurrency()
49 constraint->concurrency_current_ += get_concurrency();
51 if (constraint->concurrency_current_ > constraint->concurrency_maximum_)
52 constraint->concurrency_maximum_ = constraint->concurrency_current_;
54 xbt_assert(constraint->get_concurrency_limit() < 0 ||
55 constraint->concurrency_current_ <= constraint->get_concurrency_limit(),
56 "Concurrency limit overflow!");
59 void System::check_concurrency() const
61 // These checks are very expensive, so do them only if we want to debug SURF LMM
62 if (not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug))
65 for (Constraint const& cnst : constraint_set) {
67 for (Element const& elem : cnst.enabled_element_set_) {
68 xbt_assert(elem.variable->sharing_penalty_ > 0);
69 concurrency += elem.get_concurrency();
72 for (Element const& elem : cnst.disabled_element_set_) {
73 // We should have staged variables only if concurrency is reached in some constraint
74 xbt_assert(cnst.get_concurrency_limit() < 0 || elem.variable->staged_penalty_ == 0 ||
75 elem.variable->get_min_concurrency_slack() < elem.variable->concurrency_share_,
76 "should not have staged variable!");
79 xbt_assert(cnst.get_concurrency_limit() < 0 || cnst.get_concurrency_limit() >= concurrency,
80 "concurrency check failed!");
81 xbt_assert(cnst.concurrency_current_ == concurrency, "concurrency_current is out-of-date!");
84 // Check that for each variable, all corresponding elements are in the same state (i.e. same element sets)
85 for (Variable const& var : variable_set) {
86 if (var.cnsts_.empty())
89 const Element& elem = var.cnsts_[0];
90 bool belong_to_enabled = elem.enabled_element_set_hook.is_linked();
91 bool belong_to_disabled = elem.disabled_element_set_hook.is_linked();
92 bool belong_to_active = elem.active_element_set_hook.is_linked();
94 for (Element const& elem2 : var.cnsts_) {
95 xbt_assert(belong_to_enabled == elem2.enabled_element_set_hook.is_linked(),
96 "Variable inconsistency (1): enabled_element_set");
97 xbt_assert(belong_to_disabled == elem2.disabled_element_set_hook.is_linked(),
98 "Variable inconsistency (2): disabled_element_set");
99 xbt_assert(belong_to_active == elem2.active_element_set_hook.is_linked(),
100 "Variable inconsistency (3): active_element_set");
105 void System::var_free(Variable* var)
107 XBT_IN("(sys=%p, var=%p)", this, var);
110 // TODOLATER Can do better than that by leaving only the variable in only one enabled_element_set, call
111 // update_modified_set, and then remove it..
112 if (not var->cnsts_.empty())
113 update_modified_set(var->cnsts_[0].constraint);
115 for (Element& elem : var->cnsts_) {
116 if (var->sharing_penalty_ > 0)
117 elem.decrease_concurrency();
118 if (elem.enabled_element_set_hook.is_linked())
119 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set_, elem);
120 if (elem.disabled_element_set_hook.is_linked())
121 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set_, elem);
122 if (elem.active_element_set_hook.is_linked())
123 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set_, elem);
124 int nelements = elem.constraint->enabled_element_set_.size() + elem.constraint->disabled_element_set_.size();
126 make_constraint_inactive(elem.constraint);
128 on_disabled_var(elem.constraint);
135 xbt_mallocator_release(variable_mallocator_, var);
139 System::System(bool selective_update) : selective_update_active(selective_update)
141 XBT_DEBUG("Setting selective_update_active flag to %d", selective_update_active);
143 if (selective_update)
144 modified_set_ = new kernel::resource::Action::ModifiedSet();
152 while ((var = extract_variable())) {
153 auto demangled = simgrid::xbt::demangle(var->id_ ? typeid(*var->id_).name() : "(unidentified)");
154 XBT_WARN("Probable bug: a %s variable (#%d) not removed before the LMM system destruction.", demangled.get(),
158 while ((cnst = extract_constraint()))
161 xbt_mallocator_free(variable_mallocator_);
162 delete modified_set_;
165 void System::cnst_free(Constraint* cnst)
167 make_constraint_inactive(cnst);
171 Constraint::Constraint(resource::Resource* id_value, double bound_value) : bound_(bound_value), id_(id_value)
173 rank_ = next_rank_++;
176 Constraint* System::constraint_new(resource::Resource* id, double bound_value)
178 Constraint* cnst = new Constraint(id, bound_value);
179 insert_constraint(cnst);
183 void* System::variable_mallocator_new_f()
188 void System::variable_mallocator_free_f(void* var)
190 delete static_cast<Variable*>(var);
193 Variable* System::variable_new(resource::Action* id, double sharing_penalty, double bound, size_t number_of_constraints)
195 XBT_IN("(sys=%p, id=%p, penalty=%f, bound=%f, num_cons =%zu)", this, id, sharing_penalty, bound,
196 number_of_constraints);
198 Variable* var = static_cast<Variable*>(xbt_mallocator_get(variable_mallocator_));
199 var->initialize(id, sharing_penalty, bound, number_of_constraints, visited_counter_ - 1);
200 if (sharing_penalty > 0)
201 variable_set.push_front(*var);
203 variable_set.push_back(*var);
205 XBT_OUT(" returns %p", var);
209 void System::variable_free(Variable* var)
211 remove_variable(var);
215 void System::variable_free_all()
218 while ((var = extract_variable()))
222 void System::expand(Constraint* cnst, Variable* var, double consumption_weight)
226 // Check if this variable already has an active element in this constraint
227 // If it does, subtract it from the required slack
228 int current_share = 0;
229 if (var->concurrency_share_ > 1) {
230 for (const Element& elem : var->cnsts_) {
231 if (elem.constraint == cnst && elem.enabled_element_set_hook.is_linked())
232 current_share += elem.get_concurrency();
236 // Check if we need to disable the variable
237 if (var->sharing_penalty_ > 0 && var->concurrency_share_ - current_share > cnst->get_concurrency_slack()) {
238 double penalty = var->sharing_penalty_;
240 for (Element const& elem : var->cnsts_)
241 on_disabled_var(elem.constraint);
242 consumption_weight = 0;
243 var->staged_penalty_ = penalty;
244 xbt_assert(not var->sharing_penalty_);
247 xbt_assert(var->cnsts_.size() < var->cnsts_.capacity(), "Too much constraints");
249 var->cnsts_.resize(var->cnsts_.size() + 1);
250 Element& elem = var->cnsts_.back();
252 elem.consumption_weight = consumption_weight;
253 elem.constraint = cnst;
256 if (var->sharing_penalty_) {
257 elem.constraint->enabled_element_set_.push_front(elem);
258 elem.increase_concurrency();
260 elem.constraint->disabled_element_set_.push_back(elem);
262 if (not selective_update_active) {
263 make_constraint_active(cnst);
264 } else if (elem.consumption_weight > 0 || var->sharing_penalty_ > 0) {
265 make_constraint_active(cnst);
266 update_modified_set(cnst);
267 // TODOLATER: Why do we need this second call?
268 if (var->cnsts_.size() > 1)
269 update_modified_set(var->cnsts_[0].constraint);
275 void System::expand_add(Constraint* cnst, Variable* var, double value)
281 // BEWARE: In case you have multiple elements in one constraint, this will always add value to the first element.
283 std::find_if(begin(var->cnsts_), end(var->cnsts_), [&cnst](Element const& x) { return x.constraint == cnst; });
284 if (elem_it != end(var->cnsts_)) {
285 Element& elem = *elem_it;
286 if (var->sharing_penalty_)
287 elem.decrease_concurrency();
289 if (cnst->sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE)
290 elem.consumption_weight += value;
292 elem.consumption_weight = std::max(elem.consumption_weight, value);
294 // We need to check that increasing value of the element does not cross the concurrency limit
295 if (var->sharing_penalty_) {
296 if (cnst->get_concurrency_slack() < elem.get_concurrency()) {
297 double penalty = var->sharing_penalty_;
299 for (Element const& elem2 : var->cnsts_)
300 on_disabled_var(elem2.constraint);
301 var->staged_penalty_ = penalty;
302 xbt_assert(not var->sharing_penalty_);
304 elem.increase_concurrency();
306 update_modified_set(cnst);
308 expand(cnst, var, value);
313 Variable* Constraint::get_variable(const Element** elem) const
315 if (*elem == nullptr) {
316 // That is the first call, pick the first element among enabled_element_set (or disabled_element_set if
317 // enabled_element_set is empty)
318 if (not enabled_element_set_.empty())
319 *elem = &enabled_element_set_.front();
320 else if (not disabled_element_set_.empty())
321 *elem = &disabled_element_set_.front();
325 // elem is not null, so we carry on
326 if ((*elem)->enabled_element_set_hook.is_linked()) {
327 // Look at enabled_element_set, and jump to disabled_element_set when finished
328 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
329 if (iter != std::end(enabled_element_set_))
331 else if (not disabled_element_set_.empty())
332 *elem = &disabled_element_set_.front();
336 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
337 *elem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
341 return (*elem)->variable;
346 // if we modify the list between calls, normal version may loop forever
347 // this safe version ensures that we browse the list elements only once
348 Variable* Constraint::get_variable_safe(const Element** elem, const Element** nextelem, int* numelem) const
350 if (*elem == nullptr) {
351 *numelem = enabled_element_set_.size() + disabled_element_set_.size() - 1;
352 if (not enabled_element_set_.empty())
353 *elem = &enabled_element_set_.front();
354 else if (not disabled_element_set_.empty())
355 *elem = &disabled_element_set_.front();
366 // elem is not null, so we carry on
367 if ((*elem)->enabled_element_set_hook.is_linked()) {
368 // Look at enabled_element_set, and jump to disabled_element_set when finished
369 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
370 if (iter != std::end(enabled_element_set_))
372 else if (not disabled_element_set_.empty())
373 *nextelem = &disabled_element_set_.front();
377 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
378 *nextelem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
380 return (*elem)->variable;
385 static inline void saturated_constraints_update(double usage, int cnst_light_num, dyn_light_t& saturated_constraints,
388 xbt_assert(usage > 0, "Impossible");
390 if (*min_usage < 0 || *min_usage > usage) {
392 XBT_HERE(" min_usage=%f (cnst->remaining / cnst->usage =%f)", *min_usage, usage);
393 saturated_constraints.assign(1, cnst_light_num);
394 } else if (*min_usage == usage) {
395 saturated_constraints.emplace_back(cnst_light_num);
399 static inline void saturated_variable_set_update(const ConstraintLight* cnst_light_tab,
400 const dyn_light_t& saturated_constraints, System* sys)
402 /* Add active variables (i.e. variables that need to be set) from the set of constraints to saturate
404 for (int const& saturated_cnst : saturated_constraints) {
405 const ConstraintLight& cnst = cnst_light_tab[saturated_cnst];
406 for (Element const& elem : cnst.cnst->active_element_set_) {
407 xbt_assert(elem.variable->sharing_penalty_ > 0); // All elements of active_element_set should be active
408 if (elem.consumption_weight > 0 && not elem.variable->saturated_variable_set_hook_.is_linked())
409 sys->saturated_variable_set.push_back(*elem.variable);
414 template <class ElemList>
415 static void format_element_list(const ElemList& elem_list, s4u::Link::SharingPolicy sharing_policy, double& sum,
418 for (Element const& elem : elem_list) {
419 buf += std::to_string(elem.consumption_weight) + ".'" + std::to_string(elem.variable->rank_) + "'(" +
420 std::to_string(elem.variable->value_) + ")" +
421 (sharing_policy != s4u::Link::SharingPolicy::FATPIPE ? " + " : " , ");
422 if (sharing_policy != s4u::Link::SharingPolicy::FATPIPE)
423 sum += elem.consumption_weight * elem.variable->value_;
425 sum = std::max(sum, elem.consumption_weight * elem.variable->value_);
429 void System::print() const
431 std::string buf = std::string("MAX-MIN ( ");
433 /* Printing Objective */
434 for (Variable const& var : variable_set)
435 buf += "'" + std::to_string(var.rank_) + "'(" + std::to_string(var.sharing_penalty_) + ") ";
437 XBT_DEBUG("%20s", buf.c_str());
440 XBT_DEBUG("Constraints");
441 /* Printing Constraints */
442 for (Constraint const& cnst : active_constraint_set) {
444 // Show the enabled variables
446 buf += cnst.sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE ? "(" : "max(";
447 format_element_list(cnst.enabled_element_set_, cnst.sharing_policy_, sum, buf);
448 // TODO: Adding disabled elements only for test compatibility, but do we really want them to be printed?
449 format_element_list(cnst.disabled_element_set_, cnst.sharing_policy_, sum, buf);
451 buf += "0) <= " + std::to_string(cnst.bound_) + " ('" + std::to_string(cnst.rank_) + "')";
453 if (cnst.sharing_policy_ == s4u::Link::SharingPolicy::FATPIPE) {
454 buf += " [MAX-Constraint]";
456 XBT_DEBUG("%s", buf.c_str());
458 xbt_assert(not double_positive(sum - cnst.bound_, cnst.bound_ * sg_maxmin_precision),
459 "Incorrect value (%f is not smaller than %f): %g", sum, cnst.bound_, sum - cnst.bound_);
462 XBT_DEBUG("Variables");
463 /* Printing Result */
464 for (Variable const& var : variable_set) {
465 if (var.bound_ > 0) {
466 XBT_DEBUG("'%d'(%f) : %f (<=%f)", var.rank_, var.sharing_penalty_, var.value_, var.bound_);
467 xbt_assert(not double_positive(var.value_ - var.bound_, var.bound_ * sg_maxmin_precision),
468 "Incorrect value (%f is not smaller than %f", var.value_, var.bound_);
470 XBT_DEBUG("'%d'(%f) : %f", var.rank_, var.sharing_penalty_, var.value_);
475 void System::lmm_solve()
478 XBT_IN("(sys=%p)", this);
479 /* Compute Usage and store the variables that reach the maximum. If selective_update_active is true, only
480 * constraints that changed are considered. Otherwise all constraints with active actions are considered.
482 if (selective_update_active)
483 lmm_solve(modified_constraint_set);
485 lmm_solve(active_constraint_set);
490 template <class CnstList> void System::lmm_solve(CnstList& cnst_list)
492 double min_usage = -1;
493 double min_bound = -1;
495 XBT_DEBUG("Active constraints : %zu", cnst_list.size());
496 cnst_light_vec.reserve(cnst_list.size());
497 ConstraintLight* cnst_light_tab = cnst_light_vec.data();
498 int cnst_light_num = 0;
500 for (Constraint& cnst : cnst_list) {
501 /* INIT: Collect constraints that actually need to be saturated (i.e remaining and usage are strictly positive)
502 * into cnst_light_tab. */
503 cnst.remaining_ = cnst.bound_;
504 if (not double_positive(cnst.remaining_, cnst.bound_ * sg_maxmin_precision))
507 for (Element& elem : cnst.enabled_element_set_) {
508 xbt_assert(elem.variable->sharing_penalty_ > 0.0);
509 elem.variable->value_ = 0.0;
510 if (elem.consumption_weight > 0) {
511 if (cnst.sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE)
512 cnst.usage_ += elem.consumption_weight / elem.variable->sharing_penalty_;
513 else if (cnst.usage_ < elem.consumption_weight / elem.variable->sharing_penalty_)
514 cnst.usage_ = elem.consumption_weight / elem.variable->sharing_penalty_;
517 resource::Action* action = static_cast<resource::Action*>(elem.variable->id_);
518 if (modified_set_ && not action->is_within_modified_set())
519 modified_set_->push_back(*action);
522 XBT_DEBUG("Constraint '%d' usage: %f remaining: %f concurrency: %i<=%i<=%i", cnst.rank_, cnst.usage_,
523 cnst.remaining_, cnst.concurrency_current_, cnst.concurrency_maximum_, cnst.get_concurrency_limit());
524 /* Saturated constraints update */
526 if (cnst.usage_ > 0) {
527 cnst_light_tab[cnst_light_num].cnst = &cnst;
528 cnst.cnst_light_ = &cnst_light_tab[cnst_light_num];
529 cnst_light_tab[cnst_light_num].remaining_over_usage = cnst.remaining_ / cnst.usage_;
530 saturated_constraints_update(cnst_light_tab[cnst_light_num].remaining_over_usage, cnst_light_num,
531 saturated_constraints, &min_usage);
532 xbt_assert(not cnst.active_element_set_.empty(),
533 "There is no sense adding a constraint that has no active element!");
538 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
540 /* Saturated variables update */
542 /* Fix the variables that have to be */
543 auto& var_list = saturated_variable_set;
544 for (Variable const& var : var_list) {
545 if (var.sharing_penalty_ <= 0.0)
547 /* First check if some of these variables could reach their upper bound and update min_bound accordingly. */
548 XBT_DEBUG("var=%d, var.bound=%f, var.penalty=%f, min_usage=%f, var.bound*var.penalty=%f", var.rank_, var.bound_,
549 var.sharing_penalty_, min_usage, var.bound_ * var.sharing_penalty_);
550 if ((var.bound_ > 0) && (var.bound_ * var.sharing_penalty_ < min_usage)) {
552 min_bound = var.bound_ * var.sharing_penalty_;
554 min_bound = std::min(min_bound, (var.bound_ * var.sharing_penalty_));
555 XBT_DEBUG("Updated min_bound=%f", min_bound);
559 while (not var_list.empty()) {
560 Variable& var = var_list.front();
562 // If no variable could reach its bound, deal iteratively the constraints usage ( at worst one constraint is
563 // saturated at each cycle)
564 var.value_ = min_usage / var.sharing_penalty_;
565 XBT_DEBUG("Setting var (%d) value to %f\n", var.rank_, var.value_);
567 // If there exist a variable that can reach its bound, only update it (and other with the same bound) for now.
568 if (double_equals(min_bound, var.bound_ * var.sharing_penalty_, sg_maxmin_precision)) {
569 var.value_ = var.bound_;
570 XBT_DEBUG("Setting %p (%d) value to %f\n", &var, var.rank_, var.value_);
572 // Variables which bound is different are not considered for this cycle, but they will be afterwards.
573 XBT_DEBUG("Do not consider %p (%d) \n", &var, var.rank_);
574 var_list.pop_front();
578 XBT_DEBUG("Min usage: %f, Var(%d).penalty: %f, Var(%d).value: %f ", min_usage, var.rank_, var.sharing_penalty_,
579 var.rank_, var.value_);
581 /* Update the usage of constraints where this variable is involved */
582 for (Element& elem : var.cnsts_) {
583 Constraint* cnst = elem.constraint;
584 if (cnst->sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE) {
585 // Remember: shared constraints require that sum(elem.value * var.value) < cnst->bound
586 double_update(&(cnst->remaining_), elem.consumption_weight * var.value_, cnst->bound_ * sg_maxmin_precision);
587 double_update(&(cnst->usage_), elem.consumption_weight / var.sharing_penalty_, sg_maxmin_precision);
588 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
589 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
590 not double_positive(cnst->remaining_, cnst->bound_ * sg_maxmin_precision)) {
591 if (cnst->cnst_light_) {
592 int index = (cnst->cnst_light_ - cnst_light_tab);
593 XBT_DEBUG("index: %d \t cnst_light_num: %d \t || usage: %f remaining: %f bound: %f ", index,
594 cnst_light_num, cnst->usage_, cnst->remaining_, cnst->bound_);
595 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
596 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
598 cnst->cnst_light_ = nullptr;
601 if (cnst->cnst_light_) {
602 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
605 elem.make_inactive();
607 // Remember: non-shared constraints only require that max(elem.value * var.value) < cnst->bound
609 elem.make_inactive();
610 for (const Element& elem2 : cnst->enabled_element_set_) {
611 xbt_assert(elem2.variable->sharing_penalty_ > 0);
612 if (elem2.variable->value_ > 0)
614 if (elem2.consumption_weight > 0)
615 cnst->usage_ = std::max(cnst->usage_, elem2.consumption_weight / elem2.variable->sharing_penalty_);
617 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
618 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
619 not double_positive(cnst->remaining_, cnst->bound_ * sg_maxmin_precision)) {
620 if (cnst->cnst_light_) {
621 int index = (cnst->cnst_light_ - cnst_light_tab);
622 XBT_DEBUG("index: %d \t cnst_light_num: %d \t || \t cnst: %p \t cnst->cnst_light: %p "
623 "\t cnst_light_tab: %p usage: %f remaining: %f bound: %f ",
624 index, cnst_light_num, cnst, cnst->cnst_light_, cnst_light_tab, cnst->usage_, cnst->remaining_,
626 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
627 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
629 cnst->cnst_light_ = nullptr;
632 if (cnst->cnst_light_) {
633 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
634 xbt_assert(not cnst->active_element_set_.empty(),
635 "Should not keep a maximum constraint that has no active"
636 " element! You want to check the maxmin precision and possible rounding effects.");
641 var_list.pop_front();
644 /* Find out which variables reach the maximum */
647 saturated_constraints.clear();
649 for (pos = 0; pos < cnst_light_num; pos++) {
650 xbt_assert(not cnst_light_tab[pos].cnst->active_element_set_.empty(),
651 "Cannot saturate more a constraint that has"
652 " no active element! You may want to change the maxmin precision (--cfg=maxmin/precision:<new_value>)"
653 " because of possible rounding effects.\n\tFor the record, the usage of this constraint is %g while "
654 "the maxmin precision to which it is compared is %g.\n\tThe usage of the previous constraint is %g.",
655 cnst_light_tab[pos].cnst->usage_, sg_maxmin_precision, cnst_light_tab[pos - 1].cnst->usage_);
656 saturated_constraints_update(cnst_light_tab[pos].remaining_over_usage, pos, saturated_constraints, &min_usage);
659 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
660 } while (cnst_light_num > 0);
663 if (selective_update_active)
664 remove_all_modified_set();
666 if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
673 /** @brief Attribute the value bound to var->bound.
675 * @param var the Variable*
676 * @param bound the new bound to associate with var
678 * Makes var->bound equal to bound. Whenever this function is called a change is signed in the system. To
679 * avoid false system changing detection it is a good idea to test (bound != 0) before calling it.
681 void System::update_variable_bound(Variable* var, double bound)
686 if (not var->cnsts_.empty())
687 update_modified_set(var->cnsts_[0].constraint);
690 void Variable::initialize(resource::Action* id_value, double sharing_penalty, double bound_value,
691 int number_of_constraints, unsigned visited_value)
694 rank_ = next_rank_++;
695 cnsts_.reserve(number_of_constraints);
696 sharing_penalty_ = sharing_penalty;
697 staged_penalty_ = 0.0;
698 bound_ = bound_value;
699 concurrency_share_ = 1;
701 visited_ = visited_value;
704 xbt_assert(not variable_set_hook_.is_linked());
705 xbt_assert(not saturated_variable_set_hook_.is_linked());
708 int Variable::get_min_concurrency_slack() const
710 int minslack = std::numeric_limits<int>::max();
711 for (Element const& elem : cnsts_) {
712 int slack = elem.constraint->get_concurrency_slack();
713 if (slack < minslack) {
714 // This is only an optimization, to avoid looking at more constraints when slack is already zero
723 // Small remark: In this implementation of System::enable_var() and System::disable_var(), we will meet multiple times
724 // with var when running System::update_modified_set().
725 // A priori not a big performance issue, but we might do better by calling System::update_modified_set() within the for
726 // loops (after doing the first for enabling==1, and before doing the last for disabling==1)
727 void System::enable_var(Variable* var)
729 xbt_assert(not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug) || var->can_enable());
731 var->sharing_penalty_ = var->staged_penalty_;
732 var->staged_penalty_ = 0;
734 // Enabling the variable, move var to list head. Subtlety is: here, we need to call update_modified_set AFTER
735 // moving at least one element of var.
737 simgrid::xbt::intrusive_erase(variable_set, *var);
738 variable_set.push_front(*var);
739 for (Element& elem : var->cnsts_) {
740 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set_, elem);
741 elem.constraint->enabled_element_set_.push_front(elem);
742 elem.increase_concurrency();
744 if (not var->cnsts_.empty())
745 update_modified_set(var->cnsts_[0].constraint);
747 // When used within on_disabled_var, we would get an assertion fail, because transiently there can be variables
748 // that are staged and could be activated.
749 // Anyway, caller functions all call check_concurrency() in the end.
752 void System::disable_var(Variable* var)
754 xbt_assert(not var->staged_penalty_, "Staged penalty should have been cleared");
755 // Disabling the variable, move to var to list tail. Subtlety is: here, we need to call update_modified_set
756 // BEFORE moving the last element of var.
757 simgrid::xbt::intrusive_erase(variable_set, *var);
758 variable_set.push_back(*var);
759 if (not var->cnsts_.empty())
760 update_modified_set(var->cnsts_[0].constraint);
761 for (Element& elem : var->cnsts_) {
762 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set_, elem);
763 elem.constraint->disabled_element_set_.push_back(elem);
764 if (elem.active_element_set_hook.is_linked())
765 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set_, elem);
766 elem.decrease_concurrency();
769 var->sharing_penalty_ = 0.0;
770 var->staged_penalty_ = 0.0;
775 /* /brief Find variables that can be enabled and enable them.
777 * Assuming that the variable has already been removed from non-zero penalties
778 * Can we find a staged variable to add?
779 * If yes, check that none of the constraints that this variable is involved in is at the limit of its concurrency
780 * And then add it to enabled variables
782 void System::on_disabled_var(Constraint* cnstr)
784 if (cnstr->get_concurrency_limit() < 0)
787 int numelem = cnstr->disabled_element_set_.size();
791 Element* elem = &cnstr->disabled_element_set_.front();
793 // Cannot use foreach loop, because System::enable_var() will modify disabled_element_set.. within the loop
794 while (numelem-- && elem) {
796 if (elem->disabled_element_set_hook.is_linked()) {
797 auto iter = std::next(cnstr->disabled_element_set_.iterator_to(*elem));
798 nextelem = iter != std::end(cnstr->disabled_element_set_) ? &*iter : nullptr;
803 if (elem->variable->staged_penalty_ > 0 && elem->variable->can_enable()) {
804 // Found a staged variable
805 // TODOLATER: Add random timing function to model reservation protocol fuzziness? Then how to make sure that
806 // staged variables will eventually be called?
807 enable_var(elem->variable);
810 xbt_assert(cnstr->concurrency_current_ <= cnstr->get_concurrency_limit(), "Concurrency overflow!");
811 if (cnstr->concurrency_current_ == cnstr->get_concurrency_limit())
817 // We could get an assertion fail, because transiently there can be variables that are staged and could be activated.
818 // And we need to go through all constraints of the disabled var before getting back a coherent state.
819 // Anyway, caller functions all call check_concurrency() in the end.
822 /** @brief update the penalty of a variable (disable it by passing 0 as a penalty) */
823 void System::update_variable_penalty(Variable* var, double penalty)
825 xbt_assert(penalty >= 0, "Variable penalty should not be negative!");
827 if (penalty == var->sharing_penalty_)
830 bool enabling_var = (penalty > 0 && var->sharing_penalty_ <= 0);
831 bool disabling_var = (penalty <= 0 && var->sharing_penalty_ > 0);
833 XBT_IN("(sys=%p, var=%p, penalty=%f)", this, var, penalty);
837 // Are we enabling this variable?
839 var->staged_penalty_ = penalty;
840 int minslack = var->get_min_concurrency_slack();
841 if (minslack < var->concurrency_share_) {
842 XBT_DEBUG("Staging var (instead of enabling) because min concurrency slack %i, with penalty %f and concurrency"
844 minslack, penalty, var->concurrency_share_);
847 XBT_DEBUG("Enabling var with min concurrency slack %i", minslack);
849 } else if (disabling_var) {
852 var->sharing_penalty_ = penalty;
860 void System::update_constraint_bound(Constraint* cnst, double bound)
863 update_modified_set(cnst);
864 cnst->bound_ = bound;
867 /** @brief Update the constraint set propagating recursively to other constraints so the system should not be entirely
870 * @param cnst the Constraint* affected by the change
872 * A recursive algorithm to optimize the system recalculation selecting only constraints that have changed. Each
873 * constraint change is propagated to the list of constraints for each variable.
875 void System::update_modified_set_rec(const Constraint* cnst)
877 for (Element const& elem : cnst->enabled_element_set_) {
878 Variable* var = elem.variable;
879 for (Element const& elem2 : var->cnsts_) {
880 if (var->visited_ == visited_counter_)
882 if (elem2.constraint != cnst && not elem2.constraint->modified_constraint_set_hook_.is_linked()) {
883 modified_constraint_set.push_back(*elem2.constraint);
884 update_modified_set_rec(elem2.constraint);
887 // var will be ignored in later visits as long as sys->visited_counter does not move
888 var->visited_ = visited_counter_;
892 void System::update_modified_set(Constraint* cnst)
894 /* nothing to do if selective update isn't active */
895 if (selective_update_active && not cnst->modified_constraint_set_hook_.is_linked()) {
896 modified_constraint_set.push_back(*cnst);
897 update_modified_set_rec(cnst);
901 void System::remove_all_modified_set()
903 // We cleverly un-flag all variables just by incrementing visited_counter
904 // In effect, the var->visited value will no more be equal to visited counter
905 // To be clean, when visited counter has wrapped around, we force these var->visited values so that variables that
906 // were in the modified a long long time ago are not wrongly skipped here, which would lead to very nasty bugs
907 // (i.e. not readily reproducible, and requiring a lot of run time before happening).
908 if (++visited_counter_ == 1) {
909 /* the counter wrapped around, reset each variable->visited */
910 for (Variable& var : variable_set)
913 modified_constraint_set.clear();
917 * Returns resource load (in flop per second, or byte per second, or similar)
919 * If the resource is shared (the default case), the load is sum of resource usage made by
920 * every variables located on this resource.
922 * If the resource is not shared (ie in FATPIPE mode), then the load is the max (not the sum)
923 * of all resource usages located on this resource.
925 double Constraint::get_usage() const
928 if (sharing_policy_ != s4u::Link::SharingPolicy::FATPIPE) {
929 for (Element const& elem : enabled_element_set_)
930 if (elem.consumption_weight > 0)
931 result += elem.consumption_weight * elem.variable->value_;
933 for (Element const& elem : enabled_element_set_)
934 if (elem.consumption_weight > 0)
935 result = std::max(result, elem.consumption_weight * elem.variable->value_);
940 int Constraint::get_variable_amount() const
942 return std::count_if(std::begin(enabled_element_set_), std::end(enabled_element_set_),
943 [](const Element& elem) { return elem.consumption_weight > 0; });
947 } // namespace kernel
948 } // namespace simgrid