1 /* Copyright (c) 2004-2022. 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(ker_lmm, kernel, "Kernel Linear Max-Min solver");
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(ker_lmm, 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 if (elem.constraint->enabled_element_set_.empty() && elem.constraint->disabled_element_set_.empty())
121 make_constraint_inactive(elem.constraint);
123 on_disabled_var(elem.constraint);
130 xbt_mallocator_release(variable_mallocator_, var);
134 System::System(bool selective_update) : selective_update_active(selective_update)
136 XBT_DEBUG("Setting selective_update_active flag to %d", selective_update_active);
138 if (selective_update)
139 modified_set_ = std::make_unique<kernel::resource::Action::ModifiedSet>();
144 while (Variable* var = extract_variable()) {
145 std::string demangled = boost::core::demangle(var->id_ ? typeid(*var->id_).name() : "(unidentified)");
146 XBT_WARN("Probable bug: a %s variable (#%d) not removed before the LMM system destruction.", demangled.c_str(),
150 while (Constraint* cnst = extract_constraint())
153 xbt_mallocator_free(variable_mallocator_);
156 void System::cnst_free(Constraint* cnst)
158 make_constraint_inactive(cnst);
162 Constraint::Constraint(resource::Resource* id_value, double bound_value) : bound_(bound_value), id_(id_value)
164 rank_ = next_rank_++;
167 Constraint* System::constraint_new(resource::Resource* id, double bound_value)
169 auto* cnst = new Constraint(id, bound_value);
170 insert_constraint(cnst);
174 void* System::variable_mallocator_new_f()
179 void System::variable_mallocator_free_f(void* var)
181 delete static_cast<Variable*>(var);
184 Variable* System::variable_new(resource::Action* id, double sharing_penalty, double bound, size_t number_of_constraints)
186 XBT_IN("(sys=%p, id=%p, penalty=%f, bound=%f, num_cons =%zu)", this, id, sharing_penalty, bound,
187 number_of_constraints);
189 auto* var = static_cast<Variable*>(xbt_mallocator_get(variable_mallocator_));
190 var->initialize(id, sharing_penalty, bound, number_of_constraints, visited_counter_ - 1);
191 if (sharing_penalty > 0)
192 variable_set.push_front(*var);
194 variable_set.push_back(*var);
196 XBT_OUT(" returns %p", var);
200 void System::variable_free(Variable* var)
202 remove_variable(var);
206 void System::variable_free_all()
208 while (Variable* var = extract_variable())
212 void System::expand(Constraint* cnst, Variable* var, double consumption_weight)
216 // Check if this variable already has an active element in this constraint
217 // If it does, subtract it from the required slack
218 int current_share = 0;
219 if (var->concurrency_share_ > 1) {
220 for (const Element& elem : var->cnsts_) {
221 if (elem.constraint == cnst && elem.enabled_element_set_hook.is_linked())
222 current_share += elem.get_concurrency();
226 // Check if we need to disable the variable
227 if (var->sharing_penalty_ > 0 && var->concurrency_share_ - current_share > cnst->get_concurrency_slack()) {
228 double penalty = var->sharing_penalty_;
230 for (Element const& elem : var->cnsts_)
231 on_disabled_var(elem.constraint);
232 consumption_weight = 0;
233 var->staged_penalty_ = penalty;
234 xbt_assert(not var->sharing_penalty_);
237 xbt_assert(var->cnsts_.size() < var->cnsts_.capacity(), "Too much constraints");
239 var->cnsts_.emplace_back();
240 Element& elem = var->cnsts_.back();
242 elem.consumption_weight = consumption_weight;
243 elem.max_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 elem.max_consumption_weight = std::max(elem.max_consumption_weight, value);
281 if (cnst->sharing_policy_ != Constraint::SharingPolicy::FATPIPE)
282 elem.consumption_weight += value;
284 elem.consumption_weight = std::max(elem.consumption_weight, value);
286 // We need to check that increasing value of the element does not cross the concurrency limit
287 if (var->sharing_penalty_ != 0.0) {
288 if (cnst->get_concurrency_slack() < elem.get_concurrency()) {
289 double penalty = var->sharing_penalty_;
291 for (Element const& elem2 : var->cnsts_)
292 on_disabled_var(elem2.constraint);
293 var->staged_penalty_ = penalty;
294 xbt_assert(not var->sharing_penalty_);
296 elem.increase_concurrency();
298 update_modified_set(cnst);
300 expand(cnst, var, value);
305 Variable* Constraint::get_variable(const Element** elem) const
307 if (*elem == nullptr) {
308 // That is the first call, pick the first element among enabled_element_set (or disabled_element_set if
309 // enabled_element_set is empty)
310 if (not enabled_element_set_.empty())
311 *elem = &enabled_element_set_.front();
312 else if (not disabled_element_set_.empty())
313 *elem = &disabled_element_set_.front();
317 // elem is not null, so we carry on
318 if ((*elem)->enabled_element_set_hook.is_linked()) {
319 // Look at enabled_element_set, and jump to disabled_element_set when finished
320 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
321 if (iter != std::end(enabled_element_set_))
323 else if (not disabled_element_set_.empty())
324 *elem = &disabled_element_set_.front();
328 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
329 *elem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
333 return (*elem)->variable;
338 // if we modify the list between calls, normal version may loop forever
339 // this safe version ensures that we browse the list elements only once
340 Variable* Constraint::get_variable_safe(const Element** elem, const Element** nextelem, size_t* numelem) const
342 if (*elem == nullptr) {
343 *numelem = enabled_element_set_.size() + disabled_element_set_.size() - 1;
344 if (not enabled_element_set_.empty())
345 *elem = &enabled_element_set_.front();
346 else if (not disabled_element_set_.empty())
347 *elem = &disabled_element_set_.front();
358 // elem is not null, so we carry on
359 if ((*elem)->enabled_element_set_hook.is_linked()) {
360 // Look at enabled_element_set, and jump to disabled_element_set when finished
361 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
362 if (iter != std::end(enabled_element_set_))
364 else if (not disabled_element_set_.empty())
365 *nextelem = &disabled_element_set_.front();
369 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
370 *nextelem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
372 return (*elem)->variable;
377 static inline void saturated_constraints_update(double usage, int cnst_light_num, dyn_light_t& saturated_constraints,
380 xbt_assert(usage > 0, "Impossible");
382 if (*min_usage < 0 || *min_usage > usage) {
384 XBT_HERE(" min_usage=%f (cnst->remaining / cnst->usage =%f)", *min_usage, usage);
385 saturated_constraints.assign(1, cnst_light_num);
386 } else if (*min_usage == usage) {
387 saturated_constraints.emplace_back(cnst_light_num);
391 static inline void saturated_variable_set_update(const ConstraintLight* cnst_light_tab,
392 const dyn_light_t& saturated_constraints, System* sys)
394 /* Add active variables (i.e. variables that need to be set) from the set of constraints to saturate
396 for (int const& saturated_cnst : saturated_constraints) {
397 const ConstraintLight& cnst = cnst_light_tab[saturated_cnst];
398 for (Element const& elem : cnst.cnst->active_element_set_) {
399 xbt_assert(elem.variable->sharing_penalty_ > 0); // All elements of active_element_set should be active
400 if (elem.consumption_weight > 0 && not elem.variable->saturated_variable_set_hook_.is_linked())
401 sys->saturated_variable_set.push_back(*elem.variable);
406 template <class ElemList>
407 static void format_element_list(const ElemList& elem_list, Constraint::SharingPolicy sharing_policy, double& sum,
410 for (Element const& elem : elem_list) {
411 buf += std::to_string(elem.consumption_weight) + ".'" + std::to_string(elem.variable->rank_) + "'(" +
412 std::to_string(elem.variable->value_) + ")" +
413 (sharing_policy != Constraint::SharingPolicy::FATPIPE ? " + " : " , ");
414 if (sharing_policy != Constraint::SharingPolicy::FATPIPE)
415 sum += elem.consumption_weight * elem.variable->value_;
417 sum = std::max(sum, elem.consumption_weight * elem.variable->value_);
421 void System::print() const
423 std::string buf = "MAX-MIN ( ";
425 /* Printing Objective */
426 for (Variable const& var : variable_set)
427 buf += "'" + std::to_string(var.rank_) + "'(" + std::to_string(var.sharing_penalty_) + ") ";
429 XBT_DEBUG("%20s", buf.c_str());
432 XBT_DEBUG("Constraints");
433 /* Printing Constraints */
434 for (Constraint const& cnst : active_constraint_set) {
436 // Show the enabled variables
438 buf += cnst.sharing_policy_ != Constraint::SharingPolicy::FATPIPE ? "(" : "max(";
439 format_element_list(cnst.enabled_element_set_, cnst.sharing_policy_, sum, buf);
440 // TODO: Adding disabled elements only for test compatibility, but do we really want them to be printed?
441 format_element_list(cnst.disabled_element_set_, cnst.sharing_policy_, sum, buf);
443 buf += "0) <= " + std::to_string(cnst.bound_) + " ('" + std::to_string(cnst.rank_) + "')";
445 if (cnst.sharing_policy_ == Constraint::SharingPolicy::FATPIPE) {
446 buf += " [MAX-Constraint]";
448 XBT_DEBUG("%s", buf.c_str());
450 xbt_assert(not double_positive(sum - cnst.bound_, cnst.bound_ * sg_maxmin_precision),
451 "Incorrect value (%f is not smaller than %f): %g", sum, cnst.bound_, sum - cnst.bound_);
454 XBT_DEBUG("Variables");
455 /* Printing Result */
456 for (Variable const& var : variable_set) {
457 if (var.bound_ > 0) {
458 XBT_DEBUG("'%d'(%f) : %f (<=%f)", var.rank_, var.sharing_penalty_, var.value_, var.bound_);
459 xbt_assert(not double_positive(var.value_ - var.bound_, var.bound_ * sg_maxmin_precision),
460 "Incorrect value (%f is not smaller than %f", var.value_, var.bound_);
462 XBT_DEBUG("'%d'(%f) : %f", var.rank_, var.sharing_penalty_, var.value_);
467 void System::lmm_solve()
470 XBT_IN("(sys=%p)", this);
471 /* Compute Usage and store the variables that reach the maximum. If selective_update_active is true, only
472 * constraints that changed are considered. Otherwise all constraints with active actions are considered.
474 if (selective_update_active)
475 lmm_solve(modified_constraint_set);
477 lmm_solve(active_constraint_set);
482 template <class CnstList> void System::lmm_solve(CnstList& cnst_list)
484 double min_usage = -1;
485 double min_bound = -1;
487 XBT_DEBUG("Active constraints : %zu", cnst_list.size());
488 cnst_light_vec.reserve(cnst_list.size());
489 ConstraintLight* cnst_light_tab = cnst_light_vec.data();
490 int cnst_light_num = 0;
492 for (Constraint& cnst : cnst_list) {
493 /* INIT: Collect constraints that actually need to be saturated (i.e remaining and usage are strictly positive)
494 * into cnst_light_tab. */
495 cnst.dynamic_bound_ = cnst.bound_;
496 if (cnst.get_sharing_policy() == Constraint::SharingPolicy::NONLINEAR && cnst.dyn_constraint_cb_) {
497 cnst.dynamic_bound_ = cnst.dyn_constraint_cb_(cnst.bound_, cnst.concurrency_current_);
499 cnst.remaining_ = cnst.dynamic_bound_;
500 if (not double_positive(cnst.remaining_, cnst.dynamic_bound_ * sg_maxmin_precision))
503 for (Element& elem : cnst.enabled_element_set_) {
504 xbt_assert(elem.variable->sharing_penalty_ > 0.0);
505 elem.variable->value_ = 0.0;
506 if (elem.consumption_weight > 0) {
507 if (cnst.sharing_policy_ != Constraint::SharingPolicy::FATPIPE)
508 cnst.usage_ += elem.consumption_weight / elem.variable->sharing_penalty_;
509 else if (cnst.usage_ < elem.consumption_weight / elem.variable->sharing_penalty_)
510 cnst.usage_ = elem.consumption_weight / elem.variable->sharing_penalty_;
513 resource::Action* action = elem.variable->id_;
514 if (modified_set_ && not action->is_within_modified_set())
515 modified_set_->push_back(*action);
518 XBT_DEBUG("Constraint '%d' usage: %f remaining: %f concurrency: %i<=%i<=%i", cnst.rank_, cnst.usage_,
519 cnst.remaining_, cnst.concurrency_current_, cnst.concurrency_maximum_, cnst.get_concurrency_limit());
520 /* Saturated constraints update */
522 if (cnst.usage_ > 0) {
523 cnst_light_tab[cnst_light_num].cnst = &cnst;
524 cnst.cnst_light_ = &cnst_light_tab[cnst_light_num];
525 cnst_light_tab[cnst_light_num].remaining_over_usage = cnst.remaining_ / cnst.usage_;
526 saturated_constraints_update(cnst_light_tab[cnst_light_num].remaining_over_usage, cnst_light_num,
527 saturated_constraints, &min_usage);
528 xbt_assert(not cnst.active_element_set_.empty(),
529 "There is no sense adding a constraint that has no active element!");
534 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
536 /* Saturated variables update */
538 /* Fix the variables that have to be */
539 auto& var_list = saturated_variable_set;
540 for (Variable const& var : var_list) {
541 if (var.sharing_penalty_ <= 0.0)
543 /* First check if some of these variables could reach their upper bound and update min_bound accordingly. */
544 XBT_DEBUG("var=%d, var.bound=%f, var.penalty=%f, min_usage=%f, var.bound*var.penalty=%f", var.rank_, var.bound_,
545 var.sharing_penalty_, min_usage, var.bound_ * var.sharing_penalty_);
546 if ((var.bound_ > 0) && (var.bound_ * var.sharing_penalty_ < min_usage)) {
548 min_bound = var.bound_ * var.sharing_penalty_;
550 min_bound = std::min(min_bound, (var.bound_ * var.sharing_penalty_));
551 XBT_DEBUG("Updated min_bound=%f", min_bound);
555 while (not var_list.empty()) {
556 Variable& var = var_list.front();
558 // If no variable could reach its bound, deal iteratively the constraints usage ( at worst one constraint is
559 // saturated at each cycle)
560 var.value_ = min_usage / var.sharing_penalty_;
561 XBT_DEBUG("Setting var (%d) value to %f\n", var.rank_, var.value_);
563 // If there exist a variable that can reach its bound, only update it (and other with the same bound) for now.
564 if (double_equals(min_bound, var.bound_ * var.sharing_penalty_, sg_maxmin_precision)) {
565 var.value_ = var.bound_;
566 XBT_DEBUG("Setting %p (%d) value to %f\n", &var, var.rank_, var.value_);
568 // Variables which bound is different are not considered for this cycle, but they will be afterwards.
569 XBT_DEBUG("Do not consider %p (%d)\n", &var, var.rank_);
570 var_list.pop_front();
574 XBT_DEBUG("Min usage: %f, Var(%d).penalty: %f, Var(%d).value: %f", min_usage, var.rank_, var.sharing_penalty_,
575 var.rank_, var.value_);
577 /* Update the usage of constraints where this variable is involved */
578 for (Element& elem : var.cnsts_) {
579 Constraint* cnst = elem.constraint;
580 if (cnst->sharing_policy_ != Constraint::SharingPolicy::FATPIPE) {
581 // Remember: shared constraints require that sum(elem.value * var.value) < cnst->bound
582 double_update(&(cnst->remaining_), elem.consumption_weight * var.value_,
583 cnst->dynamic_bound_ * sg_maxmin_precision);
584 double_update(&(cnst->usage_), elem.consumption_weight / var.sharing_penalty_, sg_maxmin_precision);
585 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
586 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
587 not double_positive(cnst->remaining_, cnst->dynamic_bound_ * sg_maxmin_precision)) {
588 if (cnst->cnst_light_) {
589 size_t index = (cnst->cnst_light_ - cnst_light_tab);
590 XBT_DEBUG("index: %zu \t cnst_light_num: %d \t || usage: %f remaining: %f bound: %f", index,
591 cnst_light_num, cnst->usage_, cnst->remaining_, cnst->dynamic_bound_);
592 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
593 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
595 cnst->cnst_light_ = nullptr;
598 if (cnst->cnst_light_) {
599 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
602 elem.make_inactive();
604 // Remember: non-shared constraints only require that max(elem.value * var.value) < cnst->bound
606 elem.make_inactive();
607 for (const Element& elem2 : cnst->enabled_element_set_) {
608 xbt_assert(elem2.variable->sharing_penalty_ > 0);
609 if (elem2.variable->value_ > 0)
611 if (elem2.consumption_weight > 0)
612 cnst->usage_ = std::max(cnst->usage_, elem2.consumption_weight / elem2.variable->sharing_penalty_);
614 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
615 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
616 not double_positive(cnst->remaining_, cnst->dynamic_bound_ * sg_maxmin_precision)) {
617 if (cnst->cnst_light_) {
618 size_t index = (cnst->cnst_light_ - cnst_light_tab);
619 XBT_DEBUG("index: %zu \t cnst_light_num: %d \t || \t cnst: %p \t cnst->cnst_light: %p "
620 "\t cnst_light_tab: %p usage: %f remaining: %f bound: %f",
621 index, cnst_light_num, cnst, cnst->cnst_light_, cnst_light_tab, cnst->usage_, cnst->remaining_,
622 cnst->dynamic_bound_);
623 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
624 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
626 cnst->cnst_light_ = nullptr;
629 if (cnst->cnst_light_) {
630 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
631 xbt_assert(not cnst->active_element_set_.empty(),
632 "Should not keep a maximum constraint that has no active"
633 " element! You want to check the maxmin precision and possible rounding effects.");
638 var_list.pop_front();
641 /* Find out which variables reach the maximum */
644 saturated_constraints.clear();
645 for (int pos = 0; pos < cnst_light_num; pos++) {
646 xbt_assert(not cnst_light_tab[pos].cnst->active_element_set_.empty(),
647 "Cannot saturate more a constraint that has"
648 " no active element! You may want to change the maxmin precision (--cfg=maxmin/precision:<new_value>)"
649 " because of possible rounding effects.\n\tFor the record, the usage of this constraint is %g while "
650 "the maxmin precision to which it is compared is %g.\n\tThe usage of the previous constraint is %g.",
651 cnst_light_tab[pos].cnst->usage_, sg_maxmin_precision, cnst_light_tab[pos - 1].cnst->usage_);
652 saturated_constraints_update(cnst_light_tab[pos].remaining_over_usage, pos, saturated_constraints, &min_usage);
655 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
656 } while (cnst_light_num > 0);
659 if (selective_update_active)
660 remove_all_modified_set();
662 if (XBT_LOG_ISENABLED(ker_lmm, xbt_log_priority_debug)) {
669 /** @brief Attribute the value bound to var->bound.
671 * @param var the Variable*
672 * @param bound the new bound to associate with var
674 * Makes var->bound equal to bound. Whenever this function is called a change is signed in the system. To
675 * avoid false system changing detection it is a good idea to test (bound != 0) before calling it.
677 void System::update_variable_bound(Variable* var, double bound)
682 if (not var->cnsts_.empty())
683 update_modified_set(var->cnsts_[0].constraint);
686 void Variable::initialize(resource::Action* id_value, double sharing_penalty, double bound_value,
687 size_t number_of_constraints, unsigned visited_value)
690 rank_ = next_rank_++;
691 cnsts_.reserve(number_of_constraints);
692 sharing_penalty_ = sharing_penalty;
693 staged_penalty_ = 0.0;
694 bound_ = bound_value;
695 concurrency_share_ = 1;
697 visited_ = visited_value;
700 xbt_assert(not variable_set_hook_.is_linked());
701 xbt_assert(not saturated_variable_set_hook_.is_linked());
704 int Variable::get_min_concurrency_slack() const
706 int minslack = std::numeric_limits<int>::max();
707 for (Element const& elem : cnsts_) {
708 int slack = elem.constraint->get_concurrency_slack();
709 if (slack < minslack) {
710 // This is only an optimization, to avoid looking at more constraints when slack is already zero
719 // Small remark: In this implementation of System::enable_var() and System::disable_var(), we will meet multiple times
720 // with var when running System::update_modified_set().
721 // A priori not a big performance issue, but we might do better by calling System::update_modified_set() within the for
722 // loops (after doing the first for enabling==1, and before doing the last for disabling==1)
723 void System::enable_var(Variable* var)
725 xbt_assert(not XBT_LOG_ISENABLED(ker_lmm, xbt_log_priority_debug) || var->can_enable());
727 var->sharing_penalty_ = var->staged_penalty_;
728 var->staged_penalty_ = 0;
730 // Enabling the variable, move var to list head. Subtlety is: here, we need to call update_modified_set AFTER
731 // moving at least one element of var.
733 simgrid::xbt::intrusive_erase(variable_set, *var);
734 variable_set.push_front(*var);
735 for (Element& elem : var->cnsts_) {
736 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set_, elem);
737 elem.constraint->enabled_element_set_.push_front(elem);
738 elem.increase_concurrency();
740 if (not var->cnsts_.empty())
741 update_modified_set(var->cnsts_[0].constraint);
743 // When used within on_disabled_var, we would get an assertion fail, because transiently there can be variables
744 // that are staged and could be activated.
745 // Anyway, caller functions all call check_concurrency() in the end.
748 void System::disable_var(Variable* var)
750 xbt_assert(not var->staged_penalty_, "Staged penalty should have been cleared");
751 // Disabling the variable, move to var to list tail. Subtlety is: here, we need to call update_modified_set
752 // BEFORE moving the last element of var.
753 simgrid::xbt::intrusive_erase(variable_set, *var);
754 variable_set.push_back(*var);
755 if (not var->cnsts_.empty())
756 update_modified_set(var->cnsts_[0].constraint);
757 for (Element& elem : var->cnsts_) {
758 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set_, elem);
759 elem.constraint->disabled_element_set_.push_back(elem);
760 if (elem.active_element_set_hook.is_linked())
761 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set_, elem);
762 elem.decrease_concurrency();
765 var->sharing_penalty_ = 0.0;
766 var->staged_penalty_ = 0.0;
771 /* /brief Find variables that can be enabled and enable them.
773 * Assuming that the variable has already been removed from non-zero penalties
774 * Can we find a staged variable to add?
775 * If yes, check that none of the constraints that this variable is involved in is at the limit of its concurrency
776 * And then add it to enabled variables
778 void System::on_disabled_var(Constraint* cnstr)
780 if (cnstr->get_concurrency_limit() < 0)
783 size_t numelem = cnstr->disabled_element_set_.size();
787 Element* elem = &cnstr->disabled_element_set_.front();
789 // Cannot use foreach loop, because System::enable_var() will modify disabled_element_set.. within the loop
790 while (numelem-- && elem) {
792 if (elem->disabled_element_set_hook.is_linked()) {
793 auto iter = std::next(cnstr->disabled_element_set_.iterator_to(*elem));
794 nextelem = iter != std::end(cnstr->disabled_element_set_) ? &*iter : nullptr;
799 if (elem->variable->staged_penalty_ > 0 && elem->variable->can_enable()) {
800 // Found a staged variable
801 // TODOLATER: Add random timing function to model reservation protocol fuzziness? Then how to make sure that
802 // staged variables will eventually be called?
803 enable_var(elem->variable);
806 xbt_assert(cnstr->concurrency_current_ <= cnstr->get_concurrency_limit(), "Concurrency overflow!");
807 if (cnstr->concurrency_current_ == cnstr->get_concurrency_limit())
813 // We could get an assertion fail, because transiently there can be variables that are staged and could be activated.
814 // And we need to go through all constraints of the disabled var before getting back a coherent state.
815 // Anyway, caller functions all call check_concurrency() in the end.
818 /** @brief update the penalty of a variable (disable it by passing 0 as a penalty) */
819 void System::update_variable_penalty(Variable* var, double penalty)
821 xbt_assert(penalty >= 0, "Variable penalty should not be negative!");
822 if (penalty == var->sharing_penalty_)
825 bool enabling_var = (penalty > 0 && var->sharing_penalty_ <= 0);
826 bool disabling_var = (penalty <= 0 && var->sharing_penalty_ > 0);
828 XBT_IN("(sys=%p, var=%p, var->sharing_penalty = %f, penalty=%f)", this, var, var->sharing_penalty_, penalty);
832 // Are we enabling this variable?
834 var->staged_penalty_ = penalty;
835 int minslack = var->get_min_concurrency_slack();
836 if (minslack < var->concurrency_share_) {
837 XBT_DEBUG("Staging var (instead of enabling) because min concurrency slack %i, with penalty %f and concurrency"
839 minslack, penalty, var->concurrency_share_);
842 XBT_DEBUG("Enabling var with min concurrency slack %i", minslack);
844 } else if (disabling_var) {
847 var->sharing_penalty_ = penalty;
848 if (not var->cnsts_.empty())
849 update_modified_set(var->cnsts_[0].constraint);
857 void System::update_constraint_bound(Constraint* cnst, double bound)
860 update_modified_set(cnst);
861 cnst->bound_ = bound;
864 /** @brief Update the constraint set propagating recursively to other constraints so the system should not be entirely
867 * @param cnst the Constraint* affected by the change
869 * A recursive algorithm to optimize the system recalculation selecting only constraints that have changed. Each
870 * constraint change is propagated to the list of constraints for each variable.
872 void System::update_modified_set_rec(const Constraint* cnst)
874 for (Element const& elem : cnst->enabled_element_set_) {
875 Variable* var = elem.variable;
876 for (Element const& elem2 : var->cnsts_) {
877 if (var->visited_ == visited_counter_)
879 if (elem2.constraint != cnst && not elem2.constraint->modified_constraint_set_hook_.is_linked()) {
880 modified_constraint_set.push_back(*elem2.constraint);
881 update_modified_set_rec(elem2.constraint);
884 // var will be ignored in later visits as long as sys->visited_counter does not move
885 var->visited_ = visited_counter_;
889 void System::update_modified_set(Constraint* cnst)
891 /* nothing to do if selective update isn't active */
892 if (selective_update_active && not cnst->modified_constraint_set_hook_.is_linked()) {
893 modified_constraint_set.push_back(*cnst);
894 update_modified_set_rec(cnst);
898 void System::remove_all_modified_set()
900 // We cleverly un-flag all variables just by incrementing visited_counter
901 // In effect, the var->visited value will no more be equal to visited counter
902 // To be clean, when visited counter has wrapped around, we force these var->visited values so that variables that
903 // were in the modified a long long time ago are not wrongly skipped here, which would lead to very nasty bugs
904 // (i.e. not readily reproducible, and requiring a lot of run time before happening).
905 if (++visited_counter_ == 1) {
906 /* the counter wrapped around, reset each variable->visited */
907 for (Variable& var : variable_set)
910 modified_constraint_set.clear();
914 * Returns resource load (in flop per second, or byte per second, or similar)
916 * If the resource is shared (the default case), the load is sum of resource usage made by
917 * every variables located on this resource.
919 * If the resource is not shared (ie in FATPIPE mode), then the load is the max (not the sum)
920 * of all resource usages located on this resource.
922 double Constraint::get_usage() const
925 if (sharing_policy_ != SharingPolicy::FATPIPE) {
926 for (Element const& elem : enabled_element_set_)
927 if (elem.consumption_weight > 0)
928 result += elem.consumption_weight * elem.variable->value_;
930 for (Element const& elem : enabled_element_set_)
931 if (elem.consumption_weight > 0)
932 result = std::max(result, elem.consumption_weight * elem.variable->value_);
937 int Constraint::get_variable_amount() const
939 return static_cast<int>(std::count_if(std::begin(enabled_element_set_), std::end(enabled_element_set_),
940 [](const Element& elem) { return elem.consumption_weight > 0; }));
943 void Constraint::set_sharing_policy(SharingPolicy policy, const s4u::NonLinearResourceCb& cb)
945 xbt_assert(policy == SharingPolicy::NONLINEAR || not cb,
946 "Invalid sharing policy for constraint. Callback should be used with NONLINEAR sharing policy");
947 sharing_policy_ = policy;
948 dyn_constraint_cb_ = cb;
952 } // namespace kernel
953 } // namespace simgrid