1 /* Copyright (c) 2004-2018. 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 /* \file callbacks.h */
8 #include "src/kernel/lmm/maxmin.hpp"
9 #include "xbt/backtrace.hpp"
11 #include "xbt/mallocator.h"
12 #include "xbt/sysdep.h"
13 #include "xbt/utility.hpp"
21 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf, "Logging specific to SURF (maxmin)");
23 double sg_maxmin_precision = 0.00001; /* Change this with --cfg=maxmin/precision:VALUE */
24 double sg_surf_precision = 0.00001; /* Change this with --cfg=surf/precision:VALUE */
25 int sg_concurrency_limit = -1; /* Change this with --cfg=maxmin/concurrency-limit:VALUE */
31 typedef std::vector<int> dyn_light_t;
33 int Variable::Global_debug_id = 1;
34 int Constraint::Global_debug_id = 1;
36 System* make_new_maxmin_system(bool selective_update)
38 return new System(selective_update);
41 int Element::get_concurrency() const
43 // Ignore element with weight less than one (e.g. cross-traffic)
44 return (consumption_weight >= 1) ? 1 : 0;
45 // There are other alternatives, but they will change the behaviour of the model..
46 // So do not use it unless you want to make a new model.
47 // If you do, remember to change the variables concurrency share to reflect it.
48 // Potential examples are:
49 // return (elem->weight>0)?1:0;//Include element as soon as weight is non-zero
50 // return (int)ceil(elem->weight);//Include element as the rounded-up integer value of the element weight
53 void Element::decrease_concurrency()
55 xbt_assert(constraint->concurrency_current >= get_concurrency());
56 constraint->concurrency_current -= get_concurrency();
59 void Element::increase_concurrency()
61 constraint->concurrency_current += get_concurrency();
63 if (constraint->concurrency_current > constraint->concurrency_maximum)
64 constraint->concurrency_maximum = constraint->concurrency_current;
66 xbt_assert(constraint->get_concurrency_limit() < 0 ||
67 constraint->concurrency_current <= constraint->get_concurrency_limit(),
68 "Concurrency limit overflow!");
71 void System::check_concurrency() const
73 // These checks are very expensive, so do them only if we want to debug SURF LMM
74 if (not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug))
77 for (Constraint const& cnst : constraint_set) {
79 for (Element const& elem : cnst.enabled_element_set) {
80 xbt_assert(elem.variable->sharing_weight > 0);
81 concurrency += elem.get_concurrency();
84 for (Element const& elem : cnst.disabled_element_set) {
85 // We should have staged variables only if concurrency is reached in some constraint
86 xbt_assert(cnst.get_concurrency_limit() < 0 || elem.variable->staged_weight == 0 ||
87 elem.variable->get_min_concurrency_slack() < elem.variable->concurrency_share,
88 "should not have staged variable!");
91 xbt_assert(cnst.get_concurrency_limit() < 0 || cnst.get_concurrency_limit() >= concurrency,
92 "concurrency check failed!");
93 xbt_assert(cnst.concurrency_current == concurrency, "concurrency_current is out-of-date!");
96 // Check that for each variable, all corresponding elements are in the same state (i.e. same element sets)
97 for (Variable const& var : variable_set) {
98 if (var.cnsts.empty())
101 const Element& elem = var.cnsts[0];
102 int belong_to_enabled = elem.enabled_element_set_hook.is_linked();
103 int belong_to_disabled = elem.disabled_element_set_hook.is_linked();
104 int belong_to_active = elem.active_element_set_hook.is_linked();
106 for (Element const& elem2 : var.cnsts) {
107 xbt_assert(belong_to_enabled == elem2.enabled_element_set_hook.is_linked(),
108 "Variable inconsistency (1): enabled_element_set");
109 xbt_assert(belong_to_disabled == elem2.disabled_element_set_hook.is_linked(),
110 "Variable inconsistency (2): disabled_element_set");
111 xbt_assert(belong_to_active == elem2.active_element_set_hook.is_linked(),
112 "Variable inconsistency (3): active_element_set");
117 void System::var_free(Variable* var)
119 XBT_IN("(sys=%p, var=%p)", this, var);
122 // TODOLATER Can do better than that by leaving only the variable in only one enabled_element_set, call
123 // update_modified_set, and then remove it..
124 if (not var->cnsts.empty())
125 update_modified_set(var->cnsts[0].constraint);
127 for (Element& elem : var->cnsts) {
128 if (var->sharing_weight > 0)
129 elem.decrease_concurrency();
130 if (elem.enabled_element_set_hook.is_linked())
131 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set, elem);
132 if (elem.disabled_element_set_hook.is_linked())
133 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set, elem);
134 if (elem.active_element_set_hook.is_linked())
135 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set, elem);
136 int nelements = elem.constraint->enabled_element_set.size() + elem.constraint->disabled_element_set.size();
138 make_constraint_inactive(elem.constraint);
140 on_disabled_var(elem.constraint);
147 xbt_mallocator_release(variable_mallocator, var);
151 System::System(bool selective_update) : selective_update_active(selective_update)
156 XBT_DEBUG("Setting selective_update_active flag to %d", selective_update_active);
158 variable_mallocator =
159 xbt_mallocator_new(65536, System::variable_mallocator_new_f, System::variable_mallocator_free_f, nullptr);
167 while ((var = extract_variable())) {
168 auto demangled = simgrid::xbt::demangle(typeid(*var->id).name());
169 XBT_WARN("Probable bug: a %s variable (#%d) not removed before the LMM system destruction.", demangled.get(),
173 while ((cnst = extract_constraint()))
176 xbt_mallocator_free(variable_mallocator);
177 delete modified_set_;
180 void System::cnst_free(Constraint* cnst)
182 make_constraint_inactive(cnst);
186 Constraint::Constraint(void* id_value, double bound_value) : bound(bound_value), id(id_value)
188 id_int = Global_debug_id++;
192 concurrency_limit = sg_concurrency_limit;
193 concurrency_current = 0;
194 concurrency_maximum = 0;
195 sharing_policy = 1; /* FIXME: don't hardcode the value */
199 cnst_light = nullptr;
202 Constraint* System::constraint_new(void* id, double bound_value)
204 Constraint* cnst = new Constraint(id, bound_value);
205 insert_constraint(cnst);
209 void* System::variable_mallocator_new_f()
214 void System::variable_mallocator_free_f(void* var)
216 delete static_cast<Variable*>(var);
219 Variable* System::variable_new(simgrid::kernel::resource::Action* id, double sharing_weight, double bound,
220 int number_of_constraints)
222 XBT_IN("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)", this, id, sharing_weight, bound, number_of_constraints);
224 Variable* var = static_cast<Variable*>(xbt_mallocator_get(variable_mallocator));
225 var->initialize(id, sharing_weight, bound, number_of_constraints, visited_counter - 1);
227 variable_set.push_front(*var);
229 variable_set.push_back(*var);
231 XBT_OUT(" returns %p", var);
235 void System::variable_free(Variable* var)
237 remove_variable(var);
241 void System::expand(Constraint* cnst, Variable* var, double consumption_weight)
245 // Check if this variable already has an active element in this constraint
246 // If it does, substract it from the required slack
247 int current_share = 0;
248 if (var->concurrency_share > 1) {
249 for (Element& elem : var->cnsts) {
250 if (elem.constraint == cnst && elem.enabled_element_set_hook.is_linked())
251 current_share += elem.get_concurrency();
255 // Check if we need to disable the variable
256 if (var->sharing_weight > 0 && var->concurrency_share - current_share > cnst->get_concurrency_slack()) {
257 double weight = var->sharing_weight;
259 for (Element const& elem : var->cnsts)
260 on_disabled_var(elem.constraint);
261 consumption_weight = 0;
262 var->staged_weight = weight;
263 xbt_assert(not var->sharing_weight);
266 xbt_assert(var->cnsts.size() < var->cnsts.capacity(), "Too much constraints");
268 var->cnsts.resize(var->cnsts.size() + 1);
269 Element& elem = var->cnsts.back();
271 elem.consumption_weight = consumption_weight;
272 elem.constraint = cnst;
275 if (var->sharing_weight) {
276 elem.constraint->enabled_element_set.push_front(elem);
277 elem.increase_concurrency();
279 elem.constraint->disabled_element_set.push_back(elem);
281 if (not selective_update_active) {
282 make_constraint_active(cnst);
283 } else if (elem.consumption_weight > 0 || var->sharing_weight > 0) {
284 make_constraint_active(cnst);
285 update_modified_set(cnst);
286 // TODOLATER: Why do we need this second call?
287 if (var->cnsts.size() > 1)
288 update_modified_set(var->cnsts[0].constraint);
294 void System::expand_add(Constraint* cnst, Variable* var, double value)
300 // BEWARE: In case you have multiple elements in one constraint, this will always add value to the first element.
302 std::find_if(begin(var->cnsts), end(var->cnsts), [&cnst](Element const& x) { return x.constraint == cnst; });
303 if (elem_it != end(var->cnsts)) {
304 Element& elem = *elem_it;
305 if (var->sharing_weight)
306 elem.decrease_concurrency();
308 if (cnst->sharing_policy)
309 elem.consumption_weight += value;
311 elem.consumption_weight = std::max(elem.consumption_weight, value);
313 // We need to check that increasing value of the element does not cross the concurrency limit
314 if (var->sharing_weight) {
315 if (cnst->get_concurrency_slack() < elem.get_concurrency()) {
316 double weight = var->sharing_weight;
318 for (Element const& elem2 : var->cnsts)
319 on_disabled_var(elem2.constraint);
320 var->staged_weight = weight;
321 xbt_assert(not var->sharing_weight);
323 elem.increase_concurrency();
325 update_modified_set(cnst);
327 expand(cnst, var, value);
332 Variable* Constraint::get_variable(const_lmm_element_t* elem) const
334 if (*elem == nullptr) {
335 // That is the first call, pick the first element among enabled_element_set (or disabled_element_set if
336 // enabled_element_set is empty)
337 if (not enabled_element_set.empty())
338 *elem = &enabled_element_set.front();
339 else if (not disabled_element_set.empty())
340 *elem = &disabled_element_set.front();
344 // elem is not null, so we carry on
345 if ((*elem)->enabled_element_set_hook.is_linked()) {
346 // Look at enabled_element_set, and jump to disabled_element_set when finished
347 auto iter = std::next(enabled_element_set.iterator_to(**elem));
348 if (iter != std::end(enabled_element_set))
350 else if (not disabled_element_set.empty())
351 *elem = &disabled_element_set.front();
355 auto iter = std::next(disabled_element_set.iterator_to(**elem));
356 *elem = iter != std::end(disabled_element_set) ? &*iter : nullptr;
360 return (*elem)->variable;
365 // if we modify the list between calls, normal version may loop forever
366 // this safe version ensures that we browse the list elements only once
367 Variable* Constraint::get_variable_safe(const_lmm_element_t* elem, const_lmm_element_t* nextelem, int* numelem) const
369 if (*elem == nullptr) {
370 *numelem = enabled_element_set.size() + disabled_element_set.size() - 1;
371 if (not enabled_element_set.empty())
372 *elem = &enabled_element_set.front();
373 else if (not disabled_element_set.empty())
374 *elem = &disabled_element_set.front();
385 // elem is not null, so we carry on
386 if ((*elem)->enabled_element_set_hook.is_linked()) {
387 // Look at enabled_element_set, and jump to disabled_element_set when finished
388 auto iter = std::next(enabled_element_set.iterator_to(**elem));
389 if (iter != std::end(enabled_element_set))
391 else if (not disabled_element_set.empty())
392 *nextelem = &disabled_element_set.front();
396 auto iter = std::next(disabled_element_set.iterator_to(**elem));
397 *nextelem = iter != std::end(disabled_element_set) ? &*iter : nullptr;
399 return (*elem)->variable;
404 static inline void saturated_constraints_update(double usage, int cnst_light_num, dyn_light_t& saturated_constraints,
407 xbt_assert(usage > 0, "Impossible");
409 if (*min_usage < 0 || *min_usage > usage) {
411 XBT_HERE(" min_usage=%f (cnst->remaining / cnst->usage =%f)", *min_usage, usage);
412 saturated_constraints.assign(1, cnst_light_num);
413 } else if (*min_usage == usage) {
414 saturated_constraints.emplace_back(cnst_light_num);
418 static inline void saturated_variable_set_update(ConstraintLight* cnst_light_tab,
419 const dyn_light_t& saturated_constraints, System* sys)
421 /* Add active variables (i.e. variables that need to be set) from the set of constraints to saturate
423 for (int const& saturated_cnst : saturated_constraints) {
424 ConstraintLight& cnst = cnst_light_tab[saturated_cnst];
425 for (Element const& elem : cnst.cnst->active_element_set) {
426 // Visiting active_element_set, so, by construction, should never get a zero weight, correct?
427 xbt_assert(elem.variable->sharing_weight > 0);
428 if (elem.consumption_weight > 0 && not elem.variable->saturated_variable_set_hook.is_linked())
429 sys->saturated_variable_set.push_back(*elem.variable);
434 template <class ElemList>
435 static void format_element_list(const ElemList& elem_list, int sharing_policy, double& sum, std::string& buf)
437 for (Element const& elem : elem_list) {
438 buf += std::to_string(elem.consumption_weight) + ".'" + std::to_string(elem.variable->id_int) + "'(" +
439 std::to_string(elem.variable->value) + ")" + (sharing_policy ? " + " : " , ");
441 sum += elem.consumption_weight * elem.variable->value;
443 sum = std::max(sum, elem.consumption_weight * elem.variable->value);
447 void System::print() const
449 std::string buf = std::string("MAX-MIN ( ");
451 /* Printing Objective */
452 for (Variable const& var : variable_set)
453 buf += "'" + std::to_string(var.id_int) + "'(" + std::to_string(var.sharing_weight) + ") ";
455 XBT_DEBUG("%20s", buf.c_str());
458 XBT_DEBUG("Constraints");
459 /* Printing Constraints */
460 for (Constraint const& cnst : active_constraint_set) {
462 // Show the enabled variables
464 buf += cnst.sharing_policy ? "(" : "max(";
465 format_element_list(cnst.enabled_element_set, cnst.sharing_policy, sum, buf);
466 // TODO: Adding disabled elements only for test compatibility, but do we really want them to be printed?
467 format_element_list(cnst.disabled_element_set, cnst.sharing_policy, sum, buf);
469 buf += "0) <= " + std::to_string(cnst.bound) + " ('" + std::to_string(cnst.id_int) + "')";
471 if (not cnst.sharing_policy) {
472 buf += " [MAX-Constraint]";
474 XBT_DEBUG("%s", buf.c_str());
476 xbt_assert(not double_positive(sum - cnst.bound, cnst.bound * sg_maxmin_precision),
477 "Incorrect value (%f is not smaller than %f): %g", sum, cnst.bound, sum - cnst.bound);
480 XBT_DEBUG("Variables");
481 /* Printing Result */
482 for (Variable const& var : variable_set) {
484 XBT_DEBUG("'%d'(%f) : %f (<=%f)", var.id_int, var.sharing_weight, var.value, var.bound);
485 xbt_assert(not double_positive(var.value - var.bound, var.bound * sg_maxmin_precision),
486 "Incorrect value (%f is not smaller than %f", var.value, var.bound);
488 XBT_DEBUG("'%d'(%f) : %f", var.id_int, var.sharing_weight, var.value);
493 void System::lmm_solve()
496 XBT_IN("(sys=%p)", this);
497 /* Compute Usage and store the variables that reach the maximum. If selective_update_active is true, only
498 * constraints that changed are considered. Otherwise all constraints with active actions are considered.
500 if (selective_update_active)
501 lmm_solve(modified_constraint_set);
503 lmm_solve(active_constraint_set);
508 template <class CnstList> void System::lmm_solve(CnstList& cnst_list)
510 double min_usage = -1;
511 double min_bound = -1;
513 XBT_DEBUG("Active constraints : %zu", cnst_list.size());
514 /* Init: Only modified code portions: reset the value of active variables */
515 for (Constraint const& cnst : cnst_list) {
516 for (Element const& elem : cnst.enabled_element_set) {
517 xbt_assert(elem.variable->sharing_weight > 0.0);
518 elem.variable->value = 0.0;
522 ConstraintLight* cnst_light_tab = new ConstraintLight[cnst_list.size()]();
523 int cnst_light_num = 0;
524 dyn_light_t saturated_constraints;
526 for (Constraint& cnst : cnst_list) {
527 /* INIT: Collect constraints that actually need to be saturated (i.e remaining and usage are strictly positive)
528 * into cnst_light_tab. */
529 cnst.remaining = cnst.bound;
530 if (not double_positive(cnst.remaining, cnst.bound * sg_maxmin_precision))
533 for (Element& elem : cnst.enabled_element_set) {
534 xbt_assert(elem.variable->sharing_weight > 0);
535 if (elem.consumption_weight > 0) {
536 if (cnst.sharing_policy)
537 cnst.usage += elem.consumption_weight / elem.variable->sharing_weight;
538 else if (cnst.usage < elem.consumption_weight / elem.variable->sharing_weight)
539 cnst.usage = elem.consumption_weight / elem.variable->sharing_weight;
542 simgrid::kernel::resource::Action* action = static_cast<simgrid::kernel::resource::Action*>(elem.variable->id);
543 if (modified_set_ && not action->is_within_modified_set())
544 modified_set_->push_back(*action);
547 XBT_DEBUG("Constraint '%d' usage: %f remaining: %f concurrency: %i<=%i<=%i", cnst.id_int, cnst.usage,
548 cnst.remaining, cnst.concurrency_current, cnst.concurrency_maximum, cnst.get_concurrency_limit());
549 /* Saturated constraints update */
551 if (cnst.usage > 0) {
552 cnst_light_tab[cnst_light_num].cnst = &cnst;
553 cnst.cnst_light = &cnst_light_tab[cnst_light_num];
554 cnst_light_tab[cnst_light_num].remaining_over_usage = cnst.remaining / cnst.usage;
555 saturated_constraints_update(cnst_light_tab[cnst_light_num].remaining_over_usage, cnst_light_num,
556 saturated_constraints, &min_usage);
557 xbt_assert(not cnst.active_element_set.empty(),
558 "There is no sense adding a constraint that has no active element!");
563 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
565 /* Saturated variables update */
567 /* Fix the variables that have to be */
568 auto& var_list = saturated_variable_set;
569 for (Variable const& var : var_list) {
570 if (var.sharing_weight <= 0.0)
572 /* First check if some of these variables could reach their upper bound and update min_bound accordingly. */
573 XBT_DEBUG("var=%d, var.bound=%f, var.weight=%f, min_usage=%f, var.bound*var.weight=%f", var.id_int, var.bound,
574 var.sharing_weight, min_usage, var.bound * var.sharing_weight);
575 if ((var.bound > 0) && (var.bound * var.sharing_weight < min_usage)) {
577 min_bound = var.bound * var.sharing_weight;
579 min_bound = std::min(min_bound, (var.bound * var.sharing_weight));
580 XBT_DEBUG("Updated min_bound=%f", min_bound);
584 while (not var_list.empty()) {
585 Variable& var = var_list.front();
587 // If no variable could reach its bound, deal iteratively the constraints usage ( at worst one constraint is
588 // saturated at each cycle)
589 var.value = min_usage / var.sharing_weight;
590 XBT_DEBUG("Setting var (%d) value to %f\n", var.id_int, var.value);
592 // If there exist a variable that can reach its bound, only update it (and other with the same bound) for now.
593 if (double_equals(min_bound, var.bound * var.sharing_weight, sg_maxmin_precision)) {
594 var.value = var.bound;
595 XBT_DEBUG("Setting %p (%d) value to %f\n", &var, var.id_int, var.value);
597 // Variables which bound is different are not considered for this cycle, but they will be afterwards.
598 XBT_DEBUG("Do not consider %p (%d) \n", &var, var.id_int);
599 var_list.pop_front();
603 XBT_DEBUG("Min usage: %f, Var(%d).weight: %f, Var(%d).value: %f ", min_usage, var.id_int, var.sharing_weight,
604 var.id_int, var.value);
606 /* Update the usage of contraints where this variable is involved */
607 for (Element& elem : var.cnsts) {
608 Constraint* cnst = elem.constraint;
609 if (cnst->sharing_policy) {
610 // Remember: shared constraints require that sum(elem.value * var.value) < cnst->bound
611 double_update(&(cnst->remaining), elem.consumption_weight * var.value, cnst->bound * sg_maxmin_precision);
612 double_update(&(cnst->usage), elem.consumption_weight / var.sharing_weight, sg_maxmin_precision);
613 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
614 if (not double_positive(cnst->usage, sg_maxmin_precision) ||
615 not double_positive(cnst->remaining, cnst->bound * sg_maxmin_precision)) {
616 if (cnst->cnst_light) {
617 int index = (cnst->cnst_light - cnst_light_tab);
618 XBT_DEBUG("index: %d \t cnst_light_num: %d \t || usage: %f remaining: %f bound: %f ", index,
619 cnst_light_num, cnst->usage, cnst->remaining, cnst->bound);
620 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
621 cnst_light_tab[index].cnst->cnst_light = &cnst_light_tab[index];
623 cnst->cnst_light = nullptr;
626 cnst->cnst_light->remaining_over_usage = cnst->remaining / cnst->usage;
628 elem.make_inactive();
630 // Remember: non-shared constraints only require that max(elem.value * var.value) < cnst->bound
632 elem.make_inactive();
633 for (Element& elem2 : cnst->enabled_element_set) {
634 xbt_assert(elem2.variable->sharing_weight > 0);
635 if (elem2.variable->value > 0)
637 if (elem2.consumption_weight > 0)
638 cnst->usage = std::max(cnst->usage, elem2.consumption_weight / elem2.variable->sharing_weight);
640 // If the constraint is saturated, remove it from the set of active constraints (light_tab)
641 if (not double_positive(cnst->usage, sg_maxmin_precision) ||
642 not double_positive(cnst->remaining, cnst->bound * sg_maxmin_precision)) {
643 if (cnst->cnst_light) {
644 int index = (cnst->cnst_light - cnst_light_tab);
645 XBT_DEBUG("index: %d \t cnst_light_num: %d \t || \t cnst: %p \t cnst->cnst_light: %p "
646 "\t cnst_light_tab: %p usage: %f remaining: %f bound: %f ",
647 index, cnst_light_num, cnst, cnst->cnst_light, cnst_light_tab, cnst->usage, cnst->remaining,
649 cnst_light_tab[index] = cnst_light_tab[cnst_light_num - 1];
650 cnst_light_tab[index].cnst->cnst_light = &cnst_light_tab[index];
652 cnst->cnst_light = nullptr;
655 cnst->cnst_light->remaining_over_usage = cnst->remaining / cnst->usage;
656 xbt_assert(not cnst->active_element_set.empty(),
657 "Should not keep a maximum constraint that has no active"
658 " element! You want to check the maxmin precision and possible rounding effects.");
662 var_list.pop_front();
665 /* Find out which variables reach the maximum */
668 saturated_constraints.clear();
670 for (pos = 0; pos < cnst_light_num; pos++) {
671 xbt_assert(not cnst_light_tab[pos].cnst->active_element_set.empty(),
672 "Cannot saturate more a constraint that has"
673 " no active element! You may want to change the maxmin precision (--cfg=maxmin/precision:<new_value>)"
674 " because of possible rounding effects.\n\tFor the record, the usage of this constraint is %g while "
675 "the maxmin precision to which it is compared is %g.\n\tThe usage of the previous constraint is %g.",
676 cnst_light_tab[pos].cnst->usage, sg_maxmin_precision, cnst_light_tab[pos - 1].cnst->usage);
677 saturated_constraints_update(cnst_light_tab[pos].remaining_over_usage, pos, saturated_constraints, &min_usage);
680 saturated_variable_set_update(cnst_light_tab, saturated_constraints, this);
682 } while (cnst_light_num > 0);
685 if (selective_update_active)
686 remove_all_modified_set();
688 if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
694 delete[] cnst_light_tab;
697 /** \brief Attribute the value bound to var->bound.
699 * \param var the Variable*
700 * \param bound the new bound to associate with var
702 * Makes var->bound equal to bound. Whenever this function is called a change is signed in the system. To
703 * avoid false system changing detection it is a good idea to test (bound != 0) before calling it.
705 void System::update_variable_bound(Variable* var, double bound)
710 if (not var->cnsts.empty())
711 update_modified_set(var->cnsts[0].constraint);
714 void Variable::initialize(simgrid::kernel::resource::Action* id_value, double sharing_weight_value, double bound_value,
715 int number_of_constraints, unsigned visited_value)
718 id_int = Global_debug_id++;
719 cnsts.reserve(number_of_constraints);
720 sharing_weight = sharing_weight_value;
723 concurrency_share = 1;
725 visited = visited_value;
729 func_fp = func_fp_def;
730 func_fpi = func_fpi_def;
732 xbt_assert(not variable_set_hook.is_linked());
733 xbt_assert(not saturated_variable_set_hook.is_linked());
736 int Variable::get_min_concurrency_slack() const
738 int minslack = std::numeric_limits<int>::max();
739 for (Element const& elem : cnsts) {
740 int slack = elem.constraint->get_concurrency_slack();
741 if (slack < minslack) {
742 // This is only an optimization, to avoid looking at more constraints when slack is already zero
751 // Small remark: In this implementation of System::enable_var() and System::disable_var(), we will meet multiple times
752 // with var when running System::update_modified_set().
753 // A priori not a big performance issue, but we might do better by calling System::update_modified_set() within the for
754 // loops (after doing the first for enabling==1, and before doing the last for disabling==1)
755 void System::enable_var(Variable* var)
757 xbt_assert(not XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug) || var->can_enable());
759 var->sharing_weight = var->staged_weight;
760 var->staged_weight = 0;
762 // Enabling the variable, move var to list head. Subtlety is: here, we need to call update_modified_set AFTER
763 // moving at least one element of var.
765 simgrid::xbt::intrusive_erase(variable_set, *var);
766 variable_set.push_front(*var);
767 for (Element& elem : var->cnsts) {
768 simgrid::xbt::intrusive_erase(elem.constraint->disabled_element_set, elem);
769 elem.constraint->enabled_element_set.push_front(elem);
770 elem.increase_concurrency();
772 if (not var->cnsts.empty())
773 update_modified_set(var->cnsts[0].constraint);
775 // When used within on_disabled_var, we would get an assertion fail, because transiently there can be variables
776 // that are staged and could be activated.
777 // Anyway, caller functions all call check_concurrency() in the end.
780 void System::disable_var(Variable* var)
782 xbt_assert(not var->staged_weight, "Staged weight should have been cleared");
783 // Disabling the variable, move to var to list tail. Subtlety is: here, we need to call update_modified_set
784 // BEFORE moving the last element of var.
785 simgrid::xbt::intrusive_erase(variable_set, *var);
786 variable_set.push_back(*var);
787 if (not var->cnsts.empty())
788 update_modified_set(var->cnsts[0].constraint);
789 for (Element& elem : var->cnsts) {
790 simgrid::xbt::intrusive_erase(elem.constraint->enabled_element_set, elem);
791 elem.constraint->disabled_element_set.push_back(elem);
792 if (elem.active_element_set_hook.is_linked())
793 simgrid::xbt::intrusive_erase(elem.constraint->active_element_set, elem);
794 elem.decrease_concurrency();
797 var->sharing_weight = 0.0;
798 var->staged_weight = 0.0;
803 /* /brief Find variables that can be enabled and enable them.
805 * Assuming that the variable has already been removed from non-zero weights
806 * Can we find a staged variable to add?
807 * If yes, check that none of the constraints that this variable is involved in is at the limit of its concurrency
808 * And then add it to enabled variables
810 void System::on_disabled_var(Constraint* cnstr)
812 if (cnstr->get_concurrency_limit() < 0)
815 int numelem = cnstr->disabled_element_set.size();
819 Element* elem = &cnstr->disabled_element_set.front();
821 // Cannot use foreach loop, because System::enable_var() will modify disabled_element_set.. within the loop
822 while (numelem-- && elem) {
825 if (elem->disabled_element_set_hook.is_linked()) {
826 auto iter = std::next(cnstr->disabled_element_set.iterator_to(*elem));
827 nextelem = iter != std::end(cnstr->disabled_element_set) ? &*iter : nullptr;
832 if (elem->variable->staged_weight > 0 && elem->variable->can_enable()) {
833 // Found a staged variable
834 // TODOLATER: Add random timing function to model reservation protocol fuzziness? Then how to make sure that
835 // staged variables will eventually be called?
836 enable_var(elem->variable);
839 xbt_assert(cnstr->concurrency_current <= cnstr->get_concurrency_limit(), "Concurrency overflow!");
840 if (cnstr->concurrency_current == cnstr->get_concurrency_limit())
846 // We could get an assertion fail, because transiently there can be variables that are staged and could be activated.
847 // And we need to go through all constraints of the disabled var before getting back a coherent state.
848 // Anyway, caller functions all call check_concurrency() in the end.
851 /* \brief update the weight of a variable, and enable/disable it.
852 * @return Returns whether a change was made
854 void System::update_variable_weight(Variable* var, double weight)
856 xbt_assert(weight >= 0, "Variable weight should not be negative!");
858 if (weight == var->sharing_weight)
861 int enabling_var = (weight > 0 && var->sharing_weight <= 0);
862 int disabling_var = (weight <= 0 && var->sharing_weight > 0);
864 XBT_IN("(sys=%p, var=%p, weight=%f)", this, var, weight);
868 // Are we enabling this variable?
870 var->staged_weight = weight;
871 int minslack = var->get_min_concurrency_slack();
872 if (minslack < var->concurrency_share) {
873 XBT_DEBUG("Staging var (instead of enabling) because min concurrency slack %i, with weight %f and concurrency"
875 minslack, weight, var->concurrency_share);
878 XBT_DEBUG("Enabling var with min concurrency slack %i", minslack);
880 } else if (disabling_var) {
881 // Are we disabling this variable?
884 var->sharing_weight = weight;
892 void System::update_constraint_bound(Constraint* cnst, double bound)
895 update_modified_set(cnst);
899 /** \brief Update the constraint set propagating recursively to other constraints so the system should not be entirely
902 * \param cnst the Constraint* affected by the change
904 * A recursive algorithm to optimize the system recalculation selecting only constraints that have changed. Each
905 * constraint change is propagated to the list of constraints for each variable.
907 void System::update_modified_set_rec(Constraint* cnst)
909 for (Element const& elem : cnst->enabled_element_set) {
910 Variable* var = elem.variable;
911 for (Element const& elem2 : var->cnsts) {
912 if (var->visited == visited_counter)
914 if (elem2.constraint != cnst && not elem2.constraint->modified_constraint_set_hook.is_linked()) {
915 modified_constraint_set.push_back(*elem2.constraint);
916 update_modified_set_rec(elem2.constraint);
919 // var will be ignored in later visits as long as sys->visited_counter does not move
920 var->visited = visited_counter;
924 void System::update_modified_set(Constraint* cnst)
926 /* nothing to do if selective update isn't active */
927 if (selective_update_active && not cnst->modified_constraint_set_hook.is_linked()) {
928 modified_constraint_set.push_back(*cnst);
929 update_modified_set_rec(cnst);
933 void System::remove_all_modified_set()
935 // We cleverly un-flag all variables just by incrementing visited_counter
936 // In effect, the var->visited value will no more be equal to visited counter
937 // To be clean, when visited counter has wrapped around, we force these var->visited values so that variables that
938 // were in the modified a long long time ago are not wrongly skipped here, which would lead to very nasty bugs
939 // (i.e. not readibily reproducible, and requiring a lot of run time before happening).
940 if (++visited_counter == 1) {
941 /* the counter wrapped around, reset each variable->visited */
942 for (Variable& var : variable_set)
945 modified_constraint_set.clear();
949 * Returns resource load (in flop per second, or byte per second, or similar)
951 * If the resource is shared (the default case), the load is sum of resource usage made by every variables located on
954 * If the resource is not shared (ie in FATPIPE mode), then the load is the max (not the sum) of all resource usages
955 * located on this resource.
957 double Constraint::get_usage() const
960 if (sharing_policy) {
961 for (Element const& elem : enabled_element_set)
962 if (elem.consumption_weight > 0)
963 result += elem.consumption_weight * elem.variable->value;
965 for (Element const& elem : enabled_element_set)
966 if (elem.consumption_weight > 0)
967 result = std::max(result, elem.consumption_weight * elem.variable->value);
972 int Constraint::get_variable_amount() const
974 return std::count_if(std::begin(enabled_element_set), std::end(enabled_element_set),
975 [](const Element& elem) { return elem.consumption_weight > 0; });