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(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 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.constraint = cnst;
246 if (var->sharing_penalty_ != 0.0) {
247 elem.constraint->enabled_element_set_.push_front(elem);
248 elem.increase_concurrency();
250 elem.constraint->disabled_element_set_.push_back(elem);
252 if (not selective_update_active) {
253 make_constraint_active(cnst);
254 } else if (elem.consumption_weight > 0 || var->sharing_penalty_ > 0) {
255 make_constraint_active(cnst);
256 update_modified_set(cnst);
257 // TODOLATER: Why do we need this second call?
258 if (var->cnsts_.size() > 1)
259 update_modified_set(var->cnsts_[0].constraint);
265 void System::expand_add(Constraint* cnst, Variable* var, double value)
271 // BEWARE: In case you have multiple elements in one constraint, this will always add value to the first element.
273 std::find_if(begin(var->cnsts_), end(var->cnsts_), [&cnst](Element const& x) { return x.constraint == cnst; });
274 if (elem_it != end(var->cnsts_)) {
275 Element& elem = *elem_it;
276 if (var->sharing_penalty_ != 0.0)
277 elem.decrease_concurrency();
279 if (cnst->sharing_policy_ != Constraint::SharingPolicy::FATPIPE)
280 elem.consumption_weight += value;
282 elem.consumption_weight = std::max(elem.consumption_weight, value);
284 // We need to check that increasing value of the element does not cross the concurrency limit
285 if (var->sharing_penalty_ != 0.0) {
286 if (cnst->get_concurrency_slack() < elem.get_concurrency()) {
287 double penalty = var->sharing_penalty_;
289 for (Element const& elem2 : var->cnsts_)
290 on_disabled_var(elem2.constraint);
291 var->staged_penalty_ = penalty;
292 xbt_assert(not var->sharing_penalty_);
294 elem.increase_concurrency();
296 update_modified_set(cnst);
298 expand(cnst, var, value);
303 Variable* Constraint::get_variable(const Element** elem) const
305 if (*elem == nullptr) {
306 // That is the first call, pick the first element among enabled_element_set (or disabled_element_set if
307 // enabled_element_set is empty)
308 if (not enabled_element_set_.empty())
309 *elem = &enabled_element_set_.front();
310 else if (not disabled_element_set_.empty())
311 *elem = &disabled_element_set_.front();
315 // elem is not null, so we carry on
316 if ((*elem)->enabled_element_set_hook.is_linked()) {
317 // Look at enabled_element_set, and jump to disabled_element_set when finished
318 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
319 if (iter != std::end(enabled_element_set_))
321 else if (not disabled_element_set_.empty())
322 *elem = &disabled_element_set_.front();
326 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
327 *elem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
331 return (*elem)->variable;
336 // if we modify the list between calls, normal version may loop forever
337 // this safe version ensures that we browse the list elements only once
338 Variable* Constraint::get_variable_safe(const Element** elem, const Element** nextelem, size_t* numelem) const
340 if (*elem == nullptr) {
341 *numelem = enabled_element_set_.size() + disabled_element_set_.size() - 1;
342 if (not enabled_element_set_.empty())
343 *elem = &enabled_element_set_.front();
344 else if (not disabled_element_set_.empty())
345 *elem = &disabled_element_set_.front();
356 // elem is not null, so we carry on
357 if ((*elem)->enabled_element_set_hook.is_linked()) {
358 // Look at enabled_element_set, and jump to disabled_element_set when finished
359 auto iter = std::next(enabled_element_set_.iterator_to(**elem));
360 if (iter != std::end(enabled_element_set_))
362 else if (not disabled_element_set_.empty())
363 *nextelem = &disabled_element_set_.front();
367 auto iter = std::next(disabled_element_set_.iterator_to(**elem));
368 *nextelem = iter != std::end(disabled_element_set_) ? &*iter : nullptr;
370 return (*elem)->variable;
375 static inline void saturated_constraints_update(double usage, int cnst_light_num, dyn_light_t& saturated_constraints,
378 xbt_assert(usage > 0, "Impossible");
380 if (*min_usage < 0 || *min_usage > usage) {
382 XBT_HERE(" min_usage=%f (cnst->remaining / cnst->usage =%f)", *min_usage, usage);
383 saturated_constraints.assign(1, cnst_light_num);
384 } else if (*min_usage == usage) {
385 saturated_constraints.emplace_back(cnst_light_num);
389 static inline void saturated_variable_set_update(const ConstraintLight* cnst_light_tab,
390 const dyn_light_t& saturated_constraints, System* sys)
392 /* Add active variables (i.e. variables that need to be set) from the set of constraints to saturate
394 for (int const& saturated_cnst : saturated_constraints) {
395 const ConstraintLight& cnst = cnst_light_tab[saturated_cnst];
396 for (Element const& elem : cnst.cnst->active_element_set_) {
397 xbt_assert(elem.variable->sharing_penalty_ > 0); // All elements of active_element_set should be active
398 if (elem.consumption_weight > 0 && not elem.variable->saturated_variable_set_hook_.is_linked())
399 sys->saturated_variable_set.push_back(*elem.variable);
404 template <class ElemList>
405 static void format_element_list(const ElemList& elem_list, Constraint::SharingPolicy sharing_policy, double& sum,
408 for (Element const& elem : elem_list) {
409 buf += std::to_string(elem.consumption_weight) + ".'" + std::to_string(elem.variable->rank_) + "'(" +
410 std::to_string(elem.variable->value_) + ")" +
411 (sharing_policy != Constraint::SharingPolicy::FATPIPE ? " + " : " , ");
412 if (sharing_policy != Constraint::SharingPolicy::FATPIPE)
413 sum += elem.consumption_weight * elem.variable->value_;
415 sum = std::max(sum, elem.consumption_weight * elem.variable->value_);
419 void System::print() const
421 std::string buf = "MAX-MIN ( ";
423 /* Printing Objective */
424 for (Variable const& var : variable_set)
425 buf += "'" + std::to_string(var.rank_) + "'(" + std::to_string(var.sharing_penalty_) + ") ";
427 XBT_DEBUG("%20s", buf.c_str());
430 XBT_DEBUG("Constraints");
431 /* Printing Constraints */
432 for (Constraint const& cnst : active_constraint_set) {
434 // Show the enabled variables
436 buf += cnst.sharing_policy_ != Constraint::SharingPolicy::FATPIPE ? "(" : "max(";
437 format_element_list(cnst.enabled_element_set_, cnst.sharing_policy_, sum, buf);
438 // TODO: Adding disabled elements only for test compatibility, but do we really want them to be printed?
439 format_element_list(cnst.disabled_element_set_, cnst.sharing_policy_, sum, buf);
441 buf += "0) <= " + std::to_string(cnst.bound_) + " ('" + std::to_string(cnst.rank_) + "')";
443 if (cnst.sharing_policy_ == Constraint::SharingPolicy::FATPIPE) {
444 buf += " [MAX-Constraint]";
446 XBT_DEBUG("%s", buf.c_str());
448 xbt_assert(not double_positive(sum - cnst.bound_, cnst.bound_ * sg_maxmin_precision),
449 "Incorrect value (%f is not smaller than %f): %g", sum, cnst.bound_, sum - cnst.bound_);
452 XBT_DEBUG("Variables");
453 /* Printing Result */
454 for (Variable const& var : variable_set) {
455 if (var.bound_ > 0) {
456 XBT_DEBUG("'%d'(%f) : %f (<=%f)", var.rank_, var.sharing_penalty_, var.value_, var.bound_);
457 xbt_assert(not double_positive(var.value_ - var.bound_, var.bound_ * sg_maxmin_precision),
458 "Incorrect value (%f is not smaller than %f", var.value_, var.bound_);
460 XBT_DEBUG("'%d'(%f) : %f", var.rank_, var.sharing_penalty_, var.value_);
465 void System::lmm_solve()
468 XBT_IN("(sys=%p)", this);
469 /* Compute Usage and store the variables that reach the maximum. If selective_update_active is true, only
470 * constraints that changed are considered. Otherwise all constraints with active actions are considered.
472 if (selective_update_active)
473 lmm_solve(modified_constraint_set);
475 lmm_solve(active_constraint_set);
480 template <class CnstList> void System::lmm_solve(CnstList& cnst_list)
482 double min_usage = -1;
483 double min_bound = -1;
485 XBT_DEBUG("Active constraints : %zu", cnst_list.size());
486 cnst_light_vec.reserve(cnst_list.size());
487 ConstraintLight* cnst_light_tab = cnst_light_vec.data();
488 int cnst_light_num = 0;
490 for (Constraint& cnst : cnst_list) {
491 /* INIT: Collect constraints that actually need to be saturated (i.e remaining and usage are strictly positive)
492 * into cnst_light_tab. */
493 cnst.dynamic_bound_ = cnst.bound_;
494 if (cnst.get_sharing_policy() == Constraint::SharingPolicy::NONLINEAR && cnst.dyn_constraint_cb_) {
495 cnst.dynamic_bound_ = cnst.dyn_constraint_cb_(cnst.bound_, cnst.concurrency_current_);
497 cnst.remaining_ = cnst.dynamic_bound_;
498 if (not double_positive(cnst.remaining_, cnst.dynamic_bound_ * sg_maxmin_precision))
501 for (Element& elem : cnst.enabled_element_set_) {
502 xbt_assert(elem.variable->sharing_penalty_ > 0.0);
503 elem.variable->value_ = 0.0;
504 if (elem.consumption_weight > 0) {
505 if (cnst.sharing_policy_ != Constraint::SharingPolicy::FATPIPE)
506 cnst.usage_ += elem.consumption_weight / elem.variable->sharing_penalty_;
507 else if (cnst.usage_ < elem.consumption_weight / elem.variable->sharing_penalty_)
508 cnst.usage_ = elem.consumption_weight / elem.variable->sharing_penalty_;
511 resource::Action* action = elem.variable->id_;
512 if (modified_set_ && not action->is_within_modified_set())
513 modified_set_->push_back(*action);
516 XBT_DEBUG("Constraint '%d' usage: %f remaining: %f concurrency: %i<=%i<=%i", cnst.rank_, cnst.usage_,
517 cnst.remaining_, cnst.concurrency_current_, cnst.concurrency_maximum_, cnst.get_concurrency_limit());
518 /* Saturated constraints update */
520 if (cnst.usage_ > 0) {
521 cnst_light_tab[cnst_light_num].cnst = &cnst;
522 cnst.cnst_light_ = &cnst_light_tab[cnst_light_num];
523 cnst_light_tab[cnst_light_num].remaining_over_usage = cnst.remaining_ / cnst.usage_;
524 saturated_constraints_update(cnst_light_tab[cnst_light_num].remaining_over_usage, cnst_light_num,
525 saturated_constraints, &min_usage);
526 xbt_assert(not cnst.active_element_set_.empty(),
527 "There is no sense adding a constraint that has no active element!");
532 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
534 /* Saturated variables update */
536 /* Fix the variables that have to be */
537 auto& var_list = saturated_variable_set;
538 for (Variable const& var : var_list) {
539 if (var.sharing_penalty_ <= 0.0)
541 /* First check if some of these variables could reach their upper bound and update min_bound accordingly. */
542 XBT_DEBUG("var=%d, var.bound=%f, var.penalty=%f, min_usage=%f, var.bound*var.penalty=%f", var.rank_, var.bound_,
543 var.sharing_penalty_, min_usage, var.bound_ * var.sharing_penalty_);
544 if ((var.bound_ > 0) && (var.bound_ * var.sharing_penalty_ < min_usage)) {
546 min_bound = var.bound_ * var.sharing_penalty_;
548 min_bound = std::min(min_bound, (var.bound_ * var.sharing_penalty_));
549 XBT_DEBUG("Updated min_bound=%f", min_bound);
553 while (not var_list.empty()) {
554 Variable& var = var_list.front();
556 // If no variable could reach its bound, deal iteratively the constraints usage ( at worst one constraint is
557 // saturated at each cycle)
558 var.value_ = min_usage / var.sharing_penalty_;
559 XBT_DEBUG("Setting var (%d) value to %f\n", var.rank_, var.value_);
561 // If there exist a variable that can reach its bound, only update it (and other with the same bound) for now.
562 if (double_equals(min_bound, var.bound_ * var.sharing_penalty_, sg_maxmin_precision)) {
563 var.value_ = var.bound_;
564 XBT_DEBUG("Setting %p (%d) value to %f\n", &var, var.rank_, var.value_);
566 // Variables which bound is different are not considered for this cycle, but they will be afterwards.
567 XBT_DEBUG("Do not consider %p (%d)\n", &var, var.rank_);
568 var_list.pop_front();
572 XBT_DEBUG("Min usage: %f, Var(%d).penalty: %f, Var(%d).value: %f", min_usage, var.rank_, var.sharing_penalty_,
573 var.rank_, var.value_);
575 /* Update the usage of constraints where this variable is involved */
576 for (Element& elem : var.cnsts_) {
577 Constraint* cnst = elem.constraint;
578 if (cnst->sharing_policy_ != Constraint::SharingPolicy::FATPIPE) {
579 // Remember: shared constraints require that sum(elem.value * var.value) < cnst->bound
580 double_update(&(cnst->remaining_), elem.consumption_weight * var.value_,
581 cnst->dynamic_bound_ * sg_maxmin_precision);
582 double_update(&(cnst->usage_), elem.consumption_weight / var.sharing_penalty_, sg_maxmin_precision);
583 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
584 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
585 not double_positive(cnst->remaining_, cnst->dynamic_bound_ * sg_maxmin_precision)) {
586 if (cnst->cnst_light_) {
587 size_t index = (cnst->cnst_light_ - cnst_light_tab);
588 XBT_DEBUG("index: %zu \t cnst_light_num: %d \t || usage: %f remaining: %f bound: %f", index,
589 cnst_light_num, cnst->usage_, cnst->remaining_, cnst->dynamic_bound_);
590 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
591 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
593 cnst->cnst_light_ = nullptr;
596 if (cnst->cnst_light_) {
597 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
600 elem.make_inactive();
602 // Remember: non-shared constraints only require that max(elem.value * var.value) < cnst->bound
604 elem.make_inactive();
605 for (const Element& elem2 : cnst->enabled_element_set_) {
606 xbt_assert(elem2.variable->sharing_penalty_ > 0);
607 if (elem2.variable->value_ > 0)
609 if (elem2.consumption_weight > 0)
610 cnst->usage_ = std::max(cnst->usage_, elem2.consumption_weight / elem2.variable->sharing_penalty_);
612 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
613 if (not double_positive(cnst->usage_, sg_maxmin_precision) ||
614 not double_positive(cnst->remaining_, cnst->dynamic_bound_ * sg_maxmin_precision)) {
615 if (cnst->cnst_light_) {
616 size_t index = (cnst->cnst_light_ - cnst_light_tab);
617 XBT_DEBUG("index: %zu \t cnst_light_num: %d \t || \t cnst: %p \t cnst->cnst_light: %p "
618 "\t cnst_light_tab: %p usage: %f remaining: %f bound: %f",
619 index, cnst_light_num, cnst, cnst->cnst_light_, cnst_light_tab, cnst->usage_, cnst->remaining_,
620 cnst->dynamic_bound_);
621 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
622 cnst_light_tab[index].cnst->cnst_light_ = &cnst_light_tab[index];
624 cnst->cnst_light_ = nullptr;
627 if (cnst->cnst_light_) {
628 cnst->cnst_light_->remaining_over_usage = cnst->remaining_ / cnst->usage_;
629 xbt_assert(not cnst->active_element_set_.empty(),
630 "Should not keep a maximum constraint that has no active"
631 " element! You want to check the maxmin precision and possible rounding effects.");
636 var_list.pop_front();
639 /* Find out which variables reach the maximum */
642 saturated_constraints.clear();
643 for (int pos = 0; pos < cnst_light_num; pos++) {
644 xbt_assert(not cnst_light_tab[pos].cnst->active_element_set_.empty(),
645 "Cannot saturate more a constraint that has"
646 " no active element! You may want to change the maxmin precision (--cfg=maxmin/precision:<new_value>)"
647 " because of possible rounding effects.\n\tFor the record, the usage of this constraint is %g while "
648 "the maxmin precision to which it is compared is %g.\n\tThe usage of the previous constraint is %g.",
649 cnst_light_tab[pos].cnst->usage_, sg_maxmin_precision, cnst_light_tab[pos - 1].cnst->usage_);
650 saturated_constraints_update(cnst_light_tab[pos].remaining_over_usage, pos, saturated_constraints, &min_usage);
653 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
654 } while (cnst_light_num > 0);
657 if (selective_update_active)
658 remove_all_modified_set();
660 if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
667 /** @brief Attribute the value bound to var->bound.
669 * @param var the Variable*
670 * @param bound the new bound to associate with var
672 * Makes var->bound equal to bound. Whenever this function is called a change is signed in the system. To
673 * avoid false system changing detection it is a good idea to test (bound != 0) before calling it.
675 void System::update_variable_bound(Variable* var, double bound)
680 if (not var->cnsts_.empty())
681 update_modified_set(var->cnsts_[0].constraint);
684 void Variable::initialize(resource::Action* id_value, double sharing_penalty, double bound_value,
685 size_t number_of_constraints, unsigned visited_value)
688 rank_ = next_rank_++;
689 cnsts_.reserve(number_of_constraints);
690 sharing_penalty_ = sharing_penalty;
691 staged_penalty_ = 0.0;
692 bound_ = bound_value;
693 concurrency_share_ = 1;
695 visited_ = visited_value;
698 xbt_assert(not variable_set_hook_.is_linked());
699 xbt_assert(not saturated_variable_set_hook_.is_linked());
702 int Variable::get_min_concurrency_slack() const
704 int minslack = std::numeric_limits<int>::max();
705 for (Element const& elem : cnsts_) {
706 int slack = elem.constraint->get_concurrency_slack();
707 if (slack < minslack) {
708 // This is only an optimization, to avoid looking at more constraints when slack is already zero
717 // Small remark: In this implementation of System::enable_var() and System::disable_var(), we will meet multiple times
718 // with var when running System::update_modified_set().
719 // A priori not a big performance issue, but we might do better by calling System::update_modified_set() within the for
720 // loops (after doing the first for enabling==1, and before doing the last for disabling==1)
721 void System::enable_var(Variable* var)
723 xbt_assert(not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug) || var->can_enable());
725 var->sharing_penalty_ = var->staged_penalty_;
726 var->staged_penalty_ = 0;
728 // Enabling the variable, move var to list head. Subtlety is: here, we need to call update_modified_set AFTER
729 // moving at least one element of var.
731 simgrid::xbt::intrusive_erase(variable_set, *var);
732 variable_set.push_front(*var);
733 for (Element& elem : var->cnsts_) {
734 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set_, elem);
735 elem.constraint->enabled_element_set_.push_front(elem);
736 elem.increase_concurrency();
738 if (not var->cnsts_.empty())
739 update_modified_set(var->cnsts_[0].constraint);
741 // When used within on_disabled_var, we would get an assertion fail, because transiently there can be variables
742 // that are staged and could be activated.
743 // Anyway, caller functions all call check_concurrency() in the end.
746 void System::disable_var(Variable* var)
748 xbt_assert(not var->staged_penalty_, "Staged penalty should have been cleared");
749 // Disabling the variable, move to var to list tail. Subtlety is: here, we need to call update_modified_set
750 // BEFORE moving the last element of var.
751 simgrid::xbt::intrusive_erase(variable_set, *var);
752 variable_set.push_back(*var);
753 if (not var->cnsts_.empty())
754 update_modified_set(var->cnsts_[0].constraint);
755 for (Element& elem : var->cnsts_) {
756 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set_, elem);
757 elem.constraint->disabled_element_set_.push_back(elem);
758 if (elem.active_element_set_hook.is_linked())
759 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set_, elem);
760 elem.decrease_concurrency();
763 var->sharing_penalty_ = 0.0;
764 var->staged_penalty_ = 0.0;
769 /* /brief Find variables that can be enabled and enable them.
771 * Assuming that the variable has already been removed from non-zero penalties
772 * Can we find a staged variable to add?
773 * If yes, check that none of the constraints that this variable is involved in is at the limit of its concurrency
774 * And then add it to enabled variables
776 void System::on_disabled_var(Constraint* cnstr)
778 if (cnstr->get_concurrency_limit() < 0)
781 size_t numelem = cnstr->disabled_element_set_.size();
785 Element* elem = &cnstr->disabled_element_set_.front();
787 // Cannot use foreach loop, because System::enable_var() will modify disabled_element_set.. within the loop
788 while (numelem-- && elem) {
790 if (elem->disabled_element_set_hook.is_linked()) {
791 auto iter = std::next(cnstr->disabled_element_set_.iterator_to(*elem));
792 nextelem = iter != std::end(cnstr->disabled_element_set_) ? &*iter : nullptr;
797 if (elem->variable->staged_penalty_ > 0 && elem->variable->can_enable()) {
798 // Found a staged variable
799 // TODOLATER: Add random timing function to model reservation protocol fuzziness? Then how to make sure that
800 // staged variables will eventually be called?
801 enable_var(elem->variable);
804 xbt_assert(cnstr->concurrency_current_ <= cnstr->get_concurrency_limit(), "Concurrency overflow!");
805 if (cnstr->concurrency_current_ == cnstr->get_concurrency_limit())
811 // We could get an assertion fail, because transiently there can be variables that are staged and could be activated.
812 // And we need to go through all constraints of the disabled var before getting back a coherent state.
813 // Anyway, caller functions all call check_concurrency() in the end.
816 /** @brief update the penalty of a variable (disable it by passing 0 as a penalty) */
817 void System::update_variable_penalty(Variable* var, double penalty)
819 xbt_assert(penalty >= 0, "Variable penalty should not be negative!");
820 if (penalty == var->sharing_penalty_)
823 bool enabling_var = (penalty > 0 && var->sharing_penalty_ <= 0);
824 bool disabling_var = (penalty <= 0 && var->sharing_penalty_ > 0);
826 XBT_IN("(sys=%p, var=%p, var->sharing_penalty = %f, penalty=%f)", this, var, var->sharing_penalty_, penalty);
830 // Are we enabling this variable?
832 var->staged_penalty_ = penalty;
833 int minslack = var->get_min_concurrency_slack();
834 if (minslack < var->concurrency_share_) {
835 XBT_DEBUG("Staging var (instead of enabling) because min concurrency slack %i, with penalty %f and concurrency"
837 minslack, penalty, var->concurrency_share_);
840 XBT_DEBUG("Enabling var with min concurrency slack %i", minslack);
842 } else if (disabling_var) {
845 var->sharing_penalty_ = penalty;
846 if (not var->cnsts_.empty())
847 update_modified_set(var->cnsts_[0].constraint);
855 void System::update_constraint_bound(Constraint* cnst, double bound)
858 update_modified_set(cnst);
859 cnst->bound_ = bound;
862 /** @brief Update the constraint set propagating recursively to other constraints so the system should not be entirely
865 * @param cnst the Constraint* affected by the change
867 * A recursive algorithm to optimize the system recalculation selecting only constraints that have changed. Each
868 * constraint change is propagated to the list of constraints for each variable.
870 void System::update_modified_set_rec(const Constraint* cnst)
872 for (Element const& elem : cnst->enabled_element_set_) {
873 Variable* var = elem.variable;
874 for (Element const& elem2 : var->cnsts_) {
875 if (var->visited_ == visited_counter_)
877 if (elem2.constraint != cnst && not elem2.constraint->modified_constraint_set_hook_.is_linked()) {
878 modified_constraint_set.push_back(*elem2.constraint);
879 update_modified_set_rec(elem2.constraint);
882 // var will be ignored in later visits as long as sys->visited_counter does not move
883 var->visited_ = visited_counter_;
887 void System::update_modified_set(Constraint* cnst)
889 /* nothing to do if selective update isn't active */
890 if (selective_update_active && not cnst->modified_constraint_set_hook_.is_linked()) {
891 modified_constraint_set.push_back(*cnst);
892 update_modified_set_rec(cnst);
896 void System::remove_all_modified_set()
898 // We cleverly un-flag all variables just by incrementing visited_counter
899 // In effect, the var->visited value will no more be equal to visited counter
900 // To be clean, when visited counter has wrapped around, we force these var->visited values so that variables that
901 // were in the modified a long long time ago are not wrongly skipped here, which would lead to very nasty bugs
902 // (i.e. not readily reproducible, and requiring a lot of run time before happening).
903 if (++visited_counter_ == 1) {
904 /* the counter wrapped around, reset each variable->visited */
905 for (Variable& var : variable_set)
908 modified_constraint_set.clear();
912 * Returns resource load (in flop per second, or byte per second, or similar)
914 * If the resource is shared (the default case), the load is sum of resource usage made by
915 * every variables located on this resource.
917 * If the resource is not shared (ie in FATPIPE mode), then the load is the max (not the sum)
918 * of all resource usages located on this resource.
920 double Constraint::get_usage() const
923 if (sharing_policy_ != SharingPolicy::FATPIPE) {
924 for (Element const& elem : enabled_element_set_)
925 if (elem.consumption_weight > 0)
926 result += elem.consumption_weight * elem.variable->value_;
928 for (Element const& elem : enabled_element_set_)
929 if (elem.consumption_weight > 0)
930 result = std::max(result, elem.consumption_weight * elem.variable->value_);
935 int Constraint::get_variable_amount() const
937 return static_cast<int>(std::count_if(std::begin(enabled_element_set_), std::end(enabled_element_set_),
938 [](const Element& elem) { return elem.consumption_weight > 0; }));
941 void Constraint::set_sharing_policy(SharingPolicy policy, const s4u::NonLinearResourceCb& cb)
943 xbt_assert(policy == SharingPolicy::NONLINEAR || not cb,
944 "Invalid sharing policy for constraint. Callback should be used with NONLINEAR sharing policy");
945 sharing_policy_ = policy;
946 dyn_constraint_cb_ = cb;
950 } // namespace kernel
951 } // namespace simgrid