src/mc/checker/CommunicationDeterminismChecker.cpp

   1 /* Copyright (c) 2008-2022. The SimGrid Team. All rights reserved.          */
   2
   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. */
   5
   6 #include "src/mc/checker/CommunicationDeterminismChecker.hpp"
   7 #include "src/kernel/activity/MailboxImpl.hpp"
   8 #include "src/mc/Session.hpp"
   9 #include "src/mc/mc_config.hpp"
  10 #include "src/mc/mc_exit.hpp"
  11 #include "src/mc/mc_private.hpp"
  12
  13 #include <cstdint>
  14
  15 using api = simgrid::mc::Api;
  16
  17 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_comm_determinism, mc, "Logging specific to MC communication determinism detection");
  18
  19 /********** Global variables **********/
  20
  21 std::vector<simgrid::mc::PatternCommunicationList> initial_communications_pattern;
  22 std::vector<std::vector<simgrid::mc::PatternCommunication*>> incomplete_communications_pattern;
  23
  24 /********** Static functions ***********/
  25
  26 namespace simgrid {
  27 namespace mc {
  28
  29 class StateCommDet {
  30   // State* state_;
  31
  32 public:
  33   std::vector<std::vector<simgrid::mc::PatternCommunication>> incomplete_comm_pattern_;
  34   std::vector<unsigned> communication_indices_;
  35
  36   static simgrid::xbt::Extension<simgrid::mc::State, StateCommDet> EXTENSION_ID;
  37   explicit StateCommDet(State* /* ptr*/) //: state_(ptr)
  38   {
  39     copy_incomplete_comm_pattern();
  40     copy_index_comm_pattern();
  41   }
  42
  43   void copy_incomplete_comm_pattern()
  44   {
  45     incomplete_comm_pattern_.clear();
  46     const unsigned long maxpid = api::get().get_maxpid();
  47     for (unsigned long i = 0; i < maxpid; i++) {
  48       std::vector<simgrid::mc::PatternCommunication> res;
  49       for (auto const& comm : incomplete_communications_pattern[i])
  50         res.push_back(comm->dup());
  51       incomplete_comm_pattern_.push_back(std::move(res));
  52     }
  53   }
  54
  55   void copy_index_comm_pattern()
  56   {
  57     communication_indices_.clear();
  58     for (auto const& list_process_comm : initial_communications_pattern)
  59       this->communication_indices_.push_back(list_process_comm.index_comm);
  60   }
  61 };
  62
  63 simgrid::xbt::Extension<simgrid::mc::State, StateCommDet> StateCommDet::EXTENSION_ID;
  64
  65 } // namespace mc
  66 } // namespace simgrid
  67
  68 static simgrid::mc::CommPatternDifference compare_comm_pattern(const simgrid::mc::PatternCommunication* comm1,
  69                                                                const simgrid::mc::PatternCommunication* comm2)
  70 {
  71   using simgrid::mc::CommPatternDifference;
  72   if (comm1->type != comm2->type)
  73     return CommPatternDifference::TYPE;
  74   if (comm1->rdv != comm2->rdv)
  75     return CommPatternDifference::RDV;
  76   if (comm1->src_proc != comm2->src_proc)
  77     return CommPatternDifference::SRC_PROC;
  78   if (comm1->dst_proc != comm2->dst_proc)
  79     return CommPatternDifference::DST_PROC;
  80   if (comm1->tag != comm2->tag)
  81     return CommPatternDifference::TAG;
  82   if (comm1->data.size() != comm2->data.size())
  83     return CommPatternDifference::DATA_SIZE;
  84   if (comm1->data != comm2->data)
  85     return CommPatternDifference::DATA;
  86   return CommPatternDifference::NONE;
  87 }
  88
  89 static void patterns_copy(std::vector<simgrid::mc::PatternCommunication*>& dest,
  90                              std::vector<simgrid::mc::PatternCommunication> const& source)
  91 {
  92   dest.clear();
  93   for (simgrid::mc::PatternCommunication const& comm : source) {
  94     auto* copy_comm = new simgrid::mc::PatternCommunication(comm.dup());
  95     dest.push_back(copy_comm);
  96   }
  97 }
  98
  99 static void restore_communications_pattern(simgrid::mc::State* state)
 100 {
 101   for (size_t i = 0; i < initial_communications_pattern.size(); i++)
 102     initial_communications_pattern[i].index_comm =
 103         state->extension<simgrid::mc::StateCommDet>()->communication_indices_[i];
 104
 105   const unsigned long maxpid = api::get().get_maxpid();
 106   for (unsigned long i = 0; i < maxpid; i++)
 107     patterns_copy(incomplete_communications_pattern[i],
 108                   state->extension<simgrid::mc::StateCommDet>()->incomplete_comm_pattern_[i]);
 109 }
 110
 111 static char* print_determinism_result(simgrid::mc::CommPatternDifference diff, aid_t process,
 112                                       const simgrid::mc::PatternCommunication* comm, unsigned int cursor)
 113 {
 114   char* type;
 115   char* res;
 116
 117   if (comm->type == simgrid::mc::PatternCommunicationType::send)
 118     type = bprintf("The send communications pattern of the process %ld is different!", process - 1);
 119   else
 120     type = bprintf("The recv communications pattern of the process %ld is different!", process - 1);
 121
 122   using simgrid::mc::CommPatternDifference;
 123   switch (diff) {
 124     case CommPatternDifference::TYPE:
 125       res = bprintf("%s Different type for communication #%u", type, cursor);
 126       break;
 127     case CommPatternDifference::RDV:
 128       res = bprintf("%s Different rdv for communication #%u", type, cursor);
 129       break;
 130     case CommPatternDifference::TAG:
 131       res = bprintf("%s Different tag for communication #%u", type, cursor);
 132       break;
 133     case CommPatternDifference::SRC_PROC:
 134       res = bprintf("%s Different source for communication #%u", type, cursor);
 135       break;
 136     case CommPatternDifference::DST_PROC:
 137       res = bprintf("%s Different destination for communication #%u", type, cursor);
 138       break;
 139     case CommPatternDifference::DATA_SIZE:
 140       res = bprintf("%s Different data size for communication #%u", type, cursor);
 141       break;
 142     case CommPatternDifference::DATA:
 143       res = bprintf("%s Different data for communication #%u", type, cursor);
 144       break;
 145     default:
 146       res = nullptr;
 147       break;
 148   }
 149
 150   return res;
 151 }
 152
 153 static void update_comm_pattern(simgrid::mc::PatternCommunication* comm_pattern,
 154                                 simgrid::mc::RemotePtr<simgrid::kernel::activity::CommImpl> const& comm_addr)
 155 {
 156   auto src_proc = api::get().get_src_actor(comm_addr);
 157   auto dst_proc = api::get().get_dst_actor(comm_addr);
 158   comm_pattern->src_proc = src_proc->get_pid();
 159   comm_pattern->dst_proc = dst_proc->get_pid();
 160
 161   if (comm_pattern->data.empty()) {
 162     comm_pattern->data = api::get().get_pattern_comm_data(comm_addr);
 163   }
 164 }
 165
 166 namespace simgrid {
 167 namespace mc {
 168
 169 void CommunicationDeterminismChecker::deterministic_comm_pattern(aid_t process, const PatternCommunication* comm,
 170                                                                  bool backtracking)
 171 {
 172   if (not backtracking) {
 173     PatternCommunicationList& list = initial_communications_pattern[process];
 174     CommPatternDifference diff     = compare_comm_pattern(list.list[list.index_comm].get(), comm);
 175
 176     if (diff != CommPatternDifference::NONE) {
 177       if (comm->type == PatternCommunicationType::send) {
 178         this->send_deterministic = false;
 179         if (this->send_diff != nullptr)
 180           xbt_free(this->send_diff);
 181         this->send_diff = print_determinism_result(diff, process, comm, list.index_comm + 1);
 182       } else {
 183         this->recv_deterministic = false;
 184         if (this->recv_diff != nullptr)
 185           xbt_free(this->recv_diff);
 186         this->recv_diff = print_determinism_result(diff, process, comm, list.index_comm + 1);
 187       }
 188       if (_sg_mc_send_determinism && not this->send_deterministic) {
 189         XBT_INFO("*********************************************************");
 190         XBT_INFO("***** Non-send-deterministic communications pattern *****");
 191         XBT_INFO("*********************************************************");
 192         XBT_INFO("%s", this->send_diff);
 193         xbt_free(this->send_diff);
 194         this->send_diff = nullptr;
 195         api::get().log_state();
 196         api::get().mc_exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 197       } else if (_sg_mc_comms_determinism && (not this->send_deterministic && not this->recv_deterministic)) {
 198         XBT_INFO("****************************************************");
 199         XBT_INFO("***** Non-deterministic communications pattern *****");
 200         XBT_INFO("****************************************************");
 201         if (this->send_diff) {
 202           XBT_INFO("%s", this->send_diff);
 203           xbt_free(this->send_diff);
 204           this->send_diff = nullptr;
 205         }
 206         if (this->recv_diff) {
 207           XBT_INFO("%s", this->recv_diff);
 208           xbt_free(this->recv_diff);
 209           this->recv_diff = nullptr;
 210         }
 211         api::get().log_state();
 212         api::get().mc_exit(SIMGRID_MC_EXIT_NON_DETERMINISM);
 213       }
 214     }
 215   }
 216 }
 217
 218 /********** Non Static functions ***********/
 219
 220 void CommunicationDeterminismChecker::get_comm_pattern(smx_simcall_t request, CallType call_type, bool backtracking)
 221 {
 222   const smx_actor_t issuer                                     = api::get().simcall_get_issuer(request);
 223   const mc::PatternCommunicationList& initial_pattern          = initial_communications_pattern[issuer->get_pid()];
 224   const std::vector<PatternCommunication*>& incomplete_pattern = incomplete_communications_pattern[issuer->get_pid()];
 225
 226   auto pattern   = std::make_unique<PatternCommunication>();
 227   pattern->index = initial_pattern.index_comm + incomplete_pattern.size();
 228
 229   if (call_type == CallType::SEND) {
 230     /* Create comm pattern */
 231     pattern->type      = PatternCommunicationType::send;
 232     pattern->comm_addr = api::get().get_comm_isend_raw_addr(request);
 233     pattern->rdv       = api::get().get_pattern_comm_rdv(pattern->comm_addr);
 234     pattern->src_proc  = api::get().get_pattern_comm_src_proc(pattern->comm_addr);
 235
 236 #if HAVE_SMPI
 237     pattern->tag = api::get().get_smpi_request_tag(request, simgrid::simix::Simcall::COMM_ISEND);
 238 #endif
 239     pattern->data = api::get().get_pattern_comm_data(pattern->comm_addr);
 240
 241 #if HAVE_SMPI
 242     auto send_detached = api::get().check_send_request_detached(request);
 243     if (send_detached) {
 244       if (this->initial_communications_pattern_done) {
 245         /* Evaluate comm determinism */
 246         this->deterministic_comm_pattern(pattern->src_proc, pattern.get(), backtracking);
 247         initial_communications_pattern[pattern->src_proc].index_comm++;
 248       } else {
 249         /* Store comm pattern */
 250         initial_communications_pattern[pattern->src_proc].list.push_back(std::move(pattern));
 251       }
 252       return;
 253     }
 254 #endif
 255   } else if (call_type == CallType::RECV) {
 256     pattern->type = PatternCommunicationType::receive;
 257     pattern->comm_addr = api::get().get_comm_isend_raw_addr(request);
 258
 259 #if HAVE_SMPI
 260     pattern->tag = api::get().get_smpi_request_tag(request, simgrid::simix::Simcall::COMM_IRECV);
 261 #endif
 262     pattern->rdv = api::get().get_pattern_comm_rdv(pattern->comm_addr);
 263     pattern->dst_proc = api::get().get_pattern_comm_dst_proc(pattern->comm_addr);
 264   } else
 265     xbt_die("Unexpected call_type %i", (int)call_type);
 266
 267   XBT_DEBUG("Insert incomplete comm pattern %p for process %ld", pattern.get(), issuer->get_pid());
 268   incomplete_communications_pattern[issuer->get_pid()].push_back(pattern.release());
 269 }
 270
 271 void CommunicationDeterminismChecker::complete_comm_pattern(RemotePtr<kernel::activity::CommImpl> const& comm_addr,
 272                                                             aid_t issuer, bool backtracking)
 273 {
 274   /* Complete comm pattern */
 275   std::vector<PatternCommunication*>& incomplete_pattern = incomplete_communications_pattern[issuer];
 276   auto current_comm_pattern =
 277       std::find_if(begin(incomplete_pattern), end(incomplete_pattern),
 278                    [&comm_addr](const PatternCommunication* comm) { return (comm->comm_addr == comm_addr); });
 279   xbt_assert(current_comm_pattern != std::end(incomplete_pattern), "Corresponding communication not found!");
 280
 281   update_comm_pattern(*current_comm_pattern, comm_addr);
 282   std::unique_ptr<PatternCommunication> comm_pattern(*current_comm_pattern);
 283   XBT_DEBUG("Remove incomplete comm pattern for process %ld at cursor %zd", issuer,
 284             std::distance(begin(incomplete_pattern), current_comm_pattern));
 285   incomplete_pattern.erase(current_comm_pattern);
 286
 287   if (this->initial_communications_pattern_done) {
 288     /* Evaluate comm determinism */
 289     this->deterministic_comm_pattern(issuer, comm_pattern.get(), backtracking);
 290     initial_communications_pattern[issuer].index_comm++;
 291   } else {
 292     /* Store comm pattern */
 293     initial_communications_pattern[issuer].list.push_back(std::move(comm_pattern));
 294   }
 295 }
 296
 297 CommunicationDeterminismChecker::CommunicationDeterminismChecker(Session* session) : Checker(session)
 298 {
 299   StateCommDet::EXTENSION_ID = simgrid::mc::State::extension_create<StateCommDet>();
 300 }
 301
 302 CommunicationDeterminismChecker::~CommunicationDeterminismChecker() = default;
 303
 304 RecordTrace CommunicationDeterminismChecker::get_record_trace() // override
 305 {
 306   RecordTrace res;
 307   for (auto const& state : stack_)
 308     res.push_back(state->get_transition());
 309   return res;
 310 }
 311
 312 std::vector<std::string> CommunicationDeterminismChecker::get_textual_trace() // override
 313 {
 314   std::vector<std::string> trace;
 315   for (auto const& state : stack_)
 316     trace.push_back(state->get_transition()->to_string());
 317   return trace;
 318 }
 319
 320 void CommunicationDeterminismChecker::log_state() // override
 321 {
 322   if (_sg_mc_comms_determinism) {
 323     if (this->send_deterministic && not this->recv_deterministic) {
 324       XBT_INFO("*******************************************************");
 325       XBT_INFO("**** Only-send-deterministic communication pattern ****");
 326       XBT_INFO("*******************************************************");
 327       XBT_INFO("%s", this->recv_diff);
 328     }
 329     if (not this->send_deterministic && this->recv_deterministic) {
 330       XBT_INFO("*******************************************************");
 331       XBT_INFO("**** Only-recv-deterministic communication pattern ****");
 332       XBT_INFO("*******************************************************");
 333       XBT_INFO("%s", this->send_diff);
 334     }
 335   }
 336   XBT_INFO("Expanded states = %ld", State::get_expanded_states());
 337   XBT_INFO("Visited states = %lu", api::get().mc_get_visited_states());
 338   XBT_INFO("Executed transitions = %lu", Transition::get_executed_transitions());
 339   XBT_INFO("Send-deterministic : %s", this->send_deterministic ? "Yes" : "No");
 340   if (_sg_mc_comms_determinism)
 341     XBT_INFO("Recv-deterministic : %s", this->recv_deterministic ? "Yes" : "No");
 342 }
 343
 344 void CommunicationDeterminismChecker::prepare()
 345 {
 346   const unsigned long maxpid = api::get().get_maxpid();
 347
 348   initial_communications_pattern.resize(maxpid);
 349   incomplete_communications_pattern.resize(maxpid);
 350
 351   auto initial_state = std::make_unique<State>();
 352   initial_state->extension_set(new StateCommDet(initial_state.get()));
 353
 354   XBT_DEBUG("********* Start communication determinism verification *********");
 355
 356   /* Add all enabled actors to the interleave set of the initial state */
 357   for (auto& act : api::get().get_actors()) {
 358     auto actor = act.copy.get_buffer();
 359     if (get_session().actor_is_enabled(actor->get_pid()))
 360       initial_state->mark_todo(actor->get_pid());
 361   }
 362
 363   stack_.push_back(std::move(initial_state));
 364 }
 365
 366 static inline bool all_communications_are_finished()
 367 {
 368   const unsigned long maxpid = api::get().get_maxpid();
 369   for (size_t current_actor = 1; current_actor < maxpid; current_actor++) {
 370     if (not incomplete_communications_pattern[current_actor].empty()) {
 371       XBT_DEBUG("Some communications are not finished, cannot stop the exploration! State not visited.");
 372       return false;
 373     }
 374   }
 375   return true;
 376 }
 377
 378 void CommunicationDeterminismChecker::restoreState()
 379 {
 380   /* Intermediate backtracking */
 381   State* last_state = stack_.back().get();
 382   if (last_state->system_state_) {
 383     api::get().restore_state(last_state->system_state_);
 384     restore_communications_pattern(last_state);
 385     return;
 386   }
 387
 388   get_session().restore_initial_state();
 389
 390   const unsigned long maxpid = api::get().get_maxpid();
 391   assert(maxpid == incomplete_communications_pattern.size());
 392   assert(maxpid == initial_communications_pattern.size());
 393   for (unsigned long j = 0; j < maxpid; j++) {
 394     incomplete_communications_pattern[j].clear();
 395     initial_communications_pattern[j].index_comm = 0;
 396   }
 397
 398   /* Traverse the stack from the state at position start and re-execute the transitions */
 399   for (std::unique_ptr<simgrid::mc::State> const& state : stack_) {
 400     if (state == stack_.back())
 401       break;
 402
 403     int req_num                    = state->get_transition()->times_considered_;
 404     const s_smx_simcall* saved_req = &state->executed_req_;
 405     xbt_assert(saved_req);
 406
 407     /* because we got a copy of the executed request, we have to fetch the
 408        real one, pointed by the request field of the issuer process */
 409
 410     const smx_actor_t issuer = api::get().simcall_get_issuer(saved_req);
 411     smx_simcall_t req        = &issuer->simcall_;
 412
 413     /* TODO : handle test and testany simcalls */
 414     CallType call = MC_get_call_type(req);
 415     state->get_transition()->replay();
 416     handle_comm_pattern(call, req, req_num, true);
 417
 418     /* Update statistics */
 419     api::get().mc_inc_visited_states();
 420   }
 421 }
 422
 423 void CommunicationDeterminismChecker::handle_comm_pattern(simgrid::mc::CallType call_type, smx_simcall_t req, int value,
 424                                                           bool backtracking)
 425 {
 426   using simgrid::mc::CallType;
 427   switch(call_type) {
 428     case CallType::NONE:
 429       break;
 430     case CallType::SEND:
 431     case CallType::RECV:
 432       get_comm_pattern(req, call_type, backtracking);
 433       break;
 434     case CallType::WAIT:
 435     case CallType::WAITANY: {
 436       RemotePtr<simgrid::kernel::activity::CommImpl> comm_addr;
 437       if (call_type == CallType::WAIT)
 438         comm_addr = remote(simcall_comm_wait__getraw__comm(req));
 439       else
 440         comm_addr = api::get().get_comm_waitany_raw_addr(req, value);
 441       auto simcall_issuer = api::get().simcall_get_issuer(req);
 442       complete_comm_pattern(comm_addr, simcall_issuer->get_pid(), backtracking);
 443     } break;
 444   default:
 445     xbt_die("Unexpected call type %i", (int)call_type);
 446   }
 447 }
 448
 449 void CommunicationDeterminismChecker::real_run()
 450 {
 451   std::unique_ptr<VisitedState> visited_state = nullptr;
 452
 453   while (not stack_.empty()) {
 454     /* Get current state */
 455     State* cur_state = stack_.back().get();
 456
 457     XBT_DEBUG("**************************************************");
 458     XBT_DEBUG("Exploration depth = %zu (state = %ld, interleaved processes = %zu)", stack_.size(), cur_state->num_,
 459               cur_state->count_todo());
 460
 461     /* Update statistics */
 462     api::get().mc_inc_visited_states();
 463
 464     int next_transition = -1;
 465     if (stack_.size() <= (std::size_t)_sg_mc_max_depth)
 466       next_transition = cur_state->next_transition();
 467
 468     if (next_transition >= 0 && visited_state == nullptr) {
 469       cur_state->execute_next(next_transition);
 470
 471       int req_num       = cur_state->get_transition()->times_considered_;
 472       smx_simcall_t req = &cur_state->executed_req_;
 473
 474       XBT_DEBUG("Execute: %s", cur_state->get_transition()->to_string().c_str());
 475
 476       std::string req_str;
 477       if (dot_output != nullptr)
 478         req_str = api::get().request_get_dot_output(cur_state->get_transition());
 479
 480       /* TODO : handle test and testany simcalls */
 481       CallType call = CallType::NONE;
 482       if (_sg_mc_comms_determinism || _sg_mc_send_determinism)
 483         call = MC_get_call_type(req);
 484
 485       handle_comm_pattern(call, req, req_num, false);
 486
 487       /* Create the new expanded state */
 488       auto next_state = std::make_unique<State>();
 489       next_state->extension_set(new StateCommDet(next_state.get()));
 490
 491       /* If comm determinism verification, we cannot stop the exploration if some communications are not finished (at
 492        * least, data are transferred). These communications  are incomplete and they cannot be analyzed and compared
 493        * with the initial pattern. */
 494       bool compare_snapshots = this->initial_communications_pattern_done && all_communications_are_finished();
 495
 496       if (_sg_mc_max_visited_states != 0)
 497         visited_state = visited_states_.addVisitedState(next_state->num_, next_state.get(), compare_snapshots);
 498       else
 499         visited_state = nullptr;
 500
 501       if (visited_state == nullptr) {
 502         /* Add all enabled actors to the interleave set of the next state */
 503         for (auto& act : api::get().get_actors()) {
 504           auto actor = act.copy.get_buffer();
 505           if (get_session().actor_is_enabled(actor->get_pid()))
 506             next_state->mark_todo(actor->get_pid());
 507         }
 508
 509         if (dot_output != nullptr)
 510           fprintf(dot_output, "\"%ld\" -> \"%ld\" [%s];\n", cur_state->num_, next_state->num_, req_str.c_str());
 511
 512       } else if (dot_output != nullptr)
 513         fprintf(dot_output, "\"%ld\" -> \"%ld\" [%s];\n", cur_state->num_,
 514                 visited_state->original_num == -1 ? visited_state->num : visited_state->original_num, req_str.c_str());
 515
 516       stack_.push_back(std::move(next_state));
 517     } else {
 518       if (stack_.size() > (std::size_t)_sg_mc_max_depth)
 519         XBT_WARN("/!\\ Max depth reached! /!\\ ");
 520       else if (visited_state != nullptr)
 521         XBT_DEBUG("State already visited (equal to state %ld), exploration stopped on this path.",
 522                   visited_state->original_num == -1 ? visited_state->num : visited_state->original_num);
 523       else
 524         XBT_DEBUG("There are no more processes to interleave. (depth %zu)", stack_.size());
 525
 526       this->initial_communications_pattern_done = true;
 527
 528       /* Trash the current state, no longer needed */
 529       XBT_DEBUG("Delete state %ld at depth %zu", cur_state->num_, stack_.size());
 530       stack_.pop_back();
 531
 532       visited_state = nullptr;
 533
 534       api::get().mc_check_deadlock();
 535
 536       while (not stack_.empty()) {
 537         std::unique_ptr<State> state(std::move(stack_.back()));
 538         stack_.pop_back();
 539         if (state->count_todo() && stack_.size() < (std::size_t)_sg_mc_max_depth) {
 540           /* We found a back-tracking point, let's loop */
 541           XBT_DEBUG("Back-tracking to state %ld at depth %zu", state->num_, stack_.size() + 1);
 542           stack_.push_back(std::move(state));
 543
 544           this->restoreState();
 545
 546           XBT_DEBUG("Back-tracking to state %ld at depth %zu done", stack_.back()->num_, stack_.size());
 547
 548           break;
 549         } else {
 550           XBT_DEBUG("Delete state %ld at depth %zu", state->num_, stack_.size() + 1);
 551         }
 552       }
 553     }
 554   }
 555
 556   api::get().log_state();
 557 }
 558
 559 void CommunicationDeterminismChecker::run()
 560 {
 561   XBT_INFO("Check communication determinism");
 562   get_session().take_initial_snapshot();
 563
 564   this->prepare();
 565   this->real_run();
 566 }
 567
 568 Checker* create_communication_determinism_checker(Session* session)
 569 {
 570   return new CommunicationDeterminismChecker(session);
 571 }
 572
 573 } // namespace mc
 574 } // namespace simgrid