1 /* Copyright (c) 2007-2018. 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 #include "SmpiHost.hpp"
8 #include "simgrid/s4u/Engine.hpp"
9 #include "smpi_coll.hpp"
10 #include "smpi_process.hpp"
11 #include "src/msg/msg_private.hpp"
12 #include "src/simix/smx_private.hpp"
13 #include "xbt/config.hpp"
15 #include <cfloat> /* DBL_MAX */
21 #include <sys/sendfile.h>
24 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smpi_kernel, smpi, "Logging specific to SMPI (kernel)");
25 #include <boost/tokenizer.hpp>
26 #include <boost/algorithm/string.hpp> /* trim_right / trim_left */
29 /* RTLD_DEEPBIND is a bad idea of GNU ld that obviously does not exist on other platforms
30 * See https://www.akkadia.org/drepper/dsohowto.pdf
31 * and https://lists.freebsd.org/pipermail/freebsd-current/2016-March/060284.html
33 #define RTLD_DEEPBIND 0
38 const char* papi_default_config_name = "default";
40 struct papi_process_data {
41 papi_counter_t counter_data;
46 using simgrid::s4u::Actor;
47 using simgrid::s4u::ActorPtr;
48 std::unordered_map<std::string, double> location2speedup;
50 static std::map</*process_id*/ ActorPtr, simgrid::smpi::Process*> process_data;
51 int process_count = 0;
52 static int smpi_exit_status = 0;
53 int smpi_universe_size = 0;
54 extern double smpi_total_benched_time;
55 xbt_os_timer_t global_timer;
57 * Setting MPI_COMM_WORLD to MPI_COMM_UNINITIALIZED (it's a variable)
58 * is important because the implementation of MPI_Comm checks
59 * "this == MPI_COMM_UNINITIALIZED"? If yes, it uses smpi_process()->comm_world()
61 * This is basically how we only have one global variable but all processes have
62 * different communicators (the one their SMPI instance uses).
64 * See smpi_comm.cpp and the functions therein for details.
66 MPI_Comm MPI_COMM_WORLD = MPI_COMM_UNINITIALIZED;
67 MPI_Errhandler *MPI_ERRORS_RETURN = nullptr;
68 MPI_Errhandler *MPI_ERRORS_ARE_FATAL = nullptr;
69 MPI_Errhandler *MPI_ERRHANDLER_NULL = nullptr;
70 // No instance gets manually created; check also the smpirun.in script as
71 // this default name is used there as well (when the <actor> tag is generated).
72 static const std::string smpi_default_instance_name("smpirun");
73 static simgrid::config::Flag<double> smpi_wtime_sleep(
74 "smpi/wtime", "Minimum time to inject inside a call to MPI_Wtime", 0.0);
75 static simgrid::config::Flag<double> smpi_init_sleep(
76 "smpi/init", "Time to inject inside a call to MPI_Init", 0.0);
78 void (*smpi_comm_copy_data_callback) (smx_activity_t, void*, size_t) = &smpi_comm_copy_buffer_callback;
80 int smpi_process_count()
85 simgrid::smpi::Process* smpi_process()
87 ActorPtr me = Actor::self();
88 if (me == nullptr) // This happens sometimes (eg, when linking against NS3 because it pulls openMPI...)
90 simgrid::msg::ActorExt* msgExt = static_cast<simgrid::msg::ActorExt*>(me->get_impl()->userdata);
91 return static_cast<simgrid::smpi::Process*>(msgExt->data);
94 simgrid::smpi::Process* smpi_process_remote(ActorPtr actor)
96 return process_data.at(actor);
99 MPI_Comm smpi_process_comm_self(){
100 return smpi_process()->comm_self();
103 void smpi_process_init(int *argc, char ***argv){
104 simgrid::smpi::Process::init(argc, argv);
107 int smpi_process_index(){
108 return simgrid::s4u::this_actor::get_pid();
111 void * smpi_process_get_user_data(){
112 return smpi_process()->get_user_data();
115 void smpi_process_set_user_data(void *data){
116 return smpi_process()->set_user_data(data);
120 int smpi_global_size()
122 char *value = getenv("SMPI_GLOBAL_SIZE");
123 xbt_assert(value,"Please set env var SMPI_GLOBAL_SIZE to the expected number of processes.");
125 return xbt_str_parse_int(value, "SMPI_GLOBAL_SIZE contains a non-numerical value: %s");
128 void smpi_comm_set_copy_data_callback(void (*callback) (smx_activity_t, void*, size_t))
130 smpi_comm_copy_data_callback = callback;
133 static void print(std::vector<std::pair<size_t, size_t>> vec) {
134 std::fprintf(stderr, "{");
135 for (auto const& elt : vec) {
136 std::fprintf(stderr, "(0x%zx, 0x%zx),", elt.first, elt.second);
138 std::fprintf(stderr, "}\n");
140 static void memcpy_private(void* dest, const void* src, std::vector<std::pair<size_t, size_t>>& private_blocks)
142 for (auto const& block : private_blocks)
143 memcpy((uint8_t*)dest+block.first, (uint8_t*)src+block.first, block.second-block.first);
146 static void check_blocks(std::vector<std::pair<size_t, size_t>> &private_blocks, size_t buff_size) {
147 for (auto const& block : private_blocks)
148 xbt_assert(block.first <= block.second && block.second <= buff_size, "Oops, bug in shared malloc.");
151 void smpi_comm_copy_buffer_callback(smx_activity_t synchro, void *buff, size_t buff_size)
153 simgrid::kernel::activity::CommImplPtr comm =
154 boost::dynamic_pointer_cast<simgrid::kernel::activity::CommImpl>(synchro);
157 size_t src_offset = 0;
158 size_t dst_offset = 0;
159 std::vector<std::pair<size_t, size_t>> src_private_blocks;
160 std::vector<std::pair<size_t, size_t>> dst_private_blocks;
161 XBT_DEBUG("Copy the data over");
162 if((src_shared=smpi_is_shared(buff, src_private_blocks, &src_offset))) {
163 XBT_DEBUG("Sender %p is shared. Let's ignore it.", buff);
164 src_private_blocks = shift_and_frame_private_blocks(src_private_blocks, src_offset, buff_size);
167 src_private_blocks.clear();
168 src_private_blocks.push_back(std::make_pair(0, buff_size));
170 if((dst_shared=smpi_is_shared((char*)comm->dst_buff, dst_private_blocks, &dst_offset))) {
171 XBT_DEBUG("Receiver %p is shared. Let's ignore it.", (char*)comm->dst_buff);
172 dst_private_blocks = shift_and_frame_private_blocks(dst_private_blocks, dst_offset, buff_size);
175 dst_private_blocks.clear();
176 dst_private_blocks.push_back(std::make_pair(0, buff_size));
178 check_blocks(src_private_blocks, buff_size);
179 check_blocks(dst_private_blocks, buff_size);
180 auto private_blocks = merge_private_blocks(src_private_blocks, dst_private_blocks);
181 check_blocks(private_blocks, buff_size);
183 if ((smpi_privatize_global_variables == SmpiPrivStrategies::Mmap) &&
184 (static_cast<char*>(buff) >= smpi_data_exe_start) &&
185 (static_cast<char*>(buff) < smpi_data_exe_start + smpi_data_exe_size)) {
186 XBT_DEBUG("Privatization : We are copying from a zone inside global memory... Saving data to temp buffer !");
187 smpi_switch_data_segment(comm->src_proc->iface());
188 tmpbuff = static_cast<void*>(xbt_malloc(buff_size));
189 memcpy_private(tmpbuff, buff, private_blocks);
192 if ((smpi_privatize_global_variables == SmpiPrivStrategies::Mmap) && ((char*)comm->dst_buff >= smpi_data_exe_start) &&
193 ((char*)comm->dst_buff < smpi_data_exe_start + smpi_data_exe_size)) {
194 XBT_DEBUG("Privatization : We are copying to a zone inside global memory - Switch data segment");
195 smpi_switch_data_segment(comm->dst_proc->iface());
197 XBT_DEBUG("Copying %zu bytes from %p to %p", buff_size, tmpbuff,comm->dst_buff);
198 memcpy_private(comm->dst_buff, tmpbuff, private_blocks);
200 if (comm->detached) {
201 // if this is a detached send, the source buffer was duplicated by SMPI
202 // sender to make the original buffer available to the application ASAP
204 //It seems that the request is used after the call there this should be free somewhere else but where???
205 //xbt_free(comm->comm.src_data);// inside SMPI the request is kept inside the user data and should be free
206 comm->src_buff = nullptr;
212 void smpi_comm_null_copy_buffer_callback(smx_activity_t comm, void *buff, size_t buff_size)
214 /* nothing done in this version */
217 static void smpi_check_options(){
218 //check correctness of MPI parameters
220 xbt_assert(xbt_cfg_get_int("smpi/async-small-thresh") <= xbt_cfg_get_int("smpi/send-is-detached-thresh"));
222 if (xbt_cfg_is_default_value("smpi/host-speed")) {
223 XBT_INFO("You did not set the power of the host running the simulation. "
224 "The timings will certainly not be accurate. "
225 "Use the option \"--cfg=smpi/host-speed:<flops>\" to set its value."
226 "Check http://simgrid.org/simgrid/latest/doc/options.html#options_smpi_bench for more information.");
229 xbt_assert(xbt_cfg_get_double("smpi/cpu-threshold") >=0,
230 "The 'smpi/cpu-threshold' option cannot have negative values [anymore]. If you want to discard "
231 "the simulation of any computation, please use 'smpi/simulate-computation:no' instead.");
235 return not process_data.empty();
238 void smpi_global_init()
240 if (not MC_is_active()) {
241 global_timer = xbt_os_timer_new();
242 xbt_os_walltimer_start(global_timer);
245 std::string filename = xbt_cfg_get_string("smpi/comp-adjustment-file");
246 if (not filename.empty()) {
247 std::ifstream fstream(filename);
248 if (not fstream.is_open()) {
249 xbt_die("Could not open file %s. Does it exist?", filename.c_str());
253 typedef boost::tokenizer< boost::escaped_list_separator<char>> Tokenizer;
254 std::getline(fstream, line); // Skip the header line
255 while (std::getline(fstream, line)) {
257 Tokenizer::iterator it = tok.begin();
258 Tokenizer::iterator end = std::next(tok.begin());
260 std::string location = *it;
261 boost::trim(location);
262 location2speedup.insert(std::pair<std::string, double>(location, std::stod(*end)));
267 // This map holds for each computation unit (such as "default" or "process1" etc.)
268 // the configuration as given by the user (counter data as a pair of (counter_name, counter_counter))
269 // and the (computed) event_set.
270 std::map</* computation unit name */ std::string, papi_process_data> units2papi_setup;
272 if (not xbt_cfg_get_string("smpi/papi-events").empty()) {
273 if (PAPI_library_init(PAPI_VER_CURRENT) != PAPI_VER_CURRENT)
274 XBT_ERROR("Could not initialize PAPI library; is it correctly installed and linked?"
275 " Expected version is %i",
278 typedef boost::tokenizer<boost::char_separator<char>> Tokenizer;
279 boost::char_separator<char> separator_units(";");
280 std::string str = xbt_cfg_get_string("smpi/papi-events");
281 Tokenizer tokens(str, separator_units);
283 // Iterate over all the computational units. This could be processes, hosts, threads, ranks... You name it.
284 // I'm not exactly sure what we will support eventually, so I'll leave it at the general term "units".
285 for (auto const& unit_it : tokens) {
286 boost::char_separator<char> separator_events(":");
287 Tokenizer event_tokens(unit_it, separator_events);
289 int event_set = PAPI_NULL;
290 if (PAPI_create_eventset(&event_set) != PAPI_OK) {
291 // TODO: Should this let the whole simulation die?
292 XBT_CRITICAL("Could not create PAPI event set during init.");
295 // NOTE: We cannot use a map here, as we must obey the order of the counters
296 // This is important for PAPI: We need to map the values of counters back
297 // to the event_names (so, when PAPI_read() has finished)!
298 papi_counter_t counters2values;
300 // Iterate over all counters that were specified for this specific
302 // Note that we need to remove the name of the unit
303 // (that could also be the "default" value), which always comes first.
304 // Hence, we start at ++(events.begin())!
305 for (Tokenizer::iterator events_it = ++(event_tokens.begin()); events_it != event_tokens.end(); ++events_it) {
307 int event_code = PAPI_NULL;
308 char* event_name = const_cast<char*>((*events_it).c_str());
309 if (PAPI_event_name_to_code(event_name, &event_code) == PAPI_OK) {
310 if (PAPI_add_event(event_set, event_code) != PAPI_OK) {
311 XBT_ERROR("Could not add PAPI event '%s'. Skipping.", event_name);
314 XBT_DEBUG("Successfully added PAPI event '%s' to the event set.", event_name);
317 XBT_CRITICAL("Could not find PAPI event '%s'. Skipping.", event_name);
321 counters2values.push_back(
322 // We cannot just pass *events_it, as this is of type const basic_string
323 std::make_pair<std::string, long long>(std::string(*events_it), 0));
326 std::string unit_name = *(event_tokens.begin());
327 papi_process_data config = {.counter_data = std::move(counters2values), .event_set = event_set};
329 units2papi_setup.insert(std::make_pair(unit_name, std::move(config)));
335 void smpi_global_destroy()
337 smpi_bench_destroy();
338 smpi_shared_destroy();
339 smpi_deployment_cleanup_instances();
341 if (simgrid::smpi::Colls::smpi_coll_cleanup_callback != nullptr)
342 simgrid::smpi::Colls::smpi_coll_cleanup_callback();
344 MPI_COMM_WORLD = MPI_COMM_NULL;
346 if (not MC_is_active()) {
347 xbt_os_timer_free(global_timer);
350 if (smpi_privatize_global_variables == SmpiPrivStrategies::Mmap)
351 smpi_destroy_global_memory_segments();
355 static void smpi_init_options(){
356 // return if already called
357 if (smpi_cpu_threshold > -1)
359 simgrid::smpi::Colls::set_collectives();
360 simgrid::smpi::Colls::smpi_coll_cleanup_callback = nullptr;
361 smpi_cpu_threshold = xbt_cfg_get_double("smpi/cpu-threshold");
362 smpi_host_speed = xbt_cfg_get_double("smpi/host-speed");
363 xbt_assert(smpi_host_speed >= 0, "You're trying to set the host_speed to a negative value (%f)", smpi_host_speed);
364 std::string smpi_privatize_option = xbt_cfg_get_string("smpi/privatization");
365 if (smpi_privatize_option == "no" || smpi_privatize_option == "0")
366 smpi_privatize_global_variables = SmpiPrivStrategies::None;
367 else if (smpi_privatize_option == "yes" || smpi_privatize_option == "1")
368 smpi_privatize_global_variables = SmpiPrivStrategies::Default;
369 else if (smpi_privatize_option == "mmap")
370 smpi_privatize_global_variables = SmpiPrivStrategies::Mmap;
371 else if (smpi_privatize_option == "dlopen")
372 smpi_privatize_global_variables = SmpiPrivStrategies::Dlopen;
374 xbt_die("Invalid value for smpi/privatization: '%s'", smpi_privatize_option.c_str());
376 if (not SMPI_switch_data_segment) {
377 XBT_DEBUG("Running without smpi_main(); disable smpi/privatization.");
378 smpi_privatize_global_variables = SmpiPrivStrategies::None;
380 #if defined(__FreeBSD__)
381 if (smpi_privatize_global_variables == SmpiPrivStrategies::Mmap) {
382 XBT_INFO("mmap privatization is broken on FreeBSD, switching to dlopen privatization instead.");
383 smpi_privatize_global_variables = SmpiPrivStrategies::Dlopen;
387 if (smpi_cpu_threshold < 0)
388 smpi_cpu_threshold = DBL_MAX;
390 std::string val = xbt_cfg_get_string("smpi/shared-malloc");
391 if ((val == "yes") || (val == "1") || (val == "on") || (val == "global")) {
392 smpi_cfg_shared_malloc = shmalloc_global;
393 } else if (val == "local") {
394 smpi_cfg_shared_malloc = shmalloc_local;
395 } else if ((val == "no") || (val == "0") || (val == "off")) {
396 smpi_cfg_shared_malloc = shmalloc_none;
398 xbt_die("Invalid value '%s' for option smpi/shared-malloc. Possible values: 'on' or 'global', 'local', 'off'",
403 typedef std::function<int(int argc, char *argv[])> smpi_entry_point_type;
404 typedef int (* smpi_c_entry_point_type)(int argc, char **argv);
405 typedef void (*smpi_fortran_entry_point_type)();
407 static int smpi_run_entry_point(smpi_entry_point_type entry_point, std::vector<std::string> args)
409 char noarg[] = {'\0'};
410 const int argc = args.size();
411 std::unique_ptr<char*[]> argv(new char*[argc + 1]);
412 for (int i = 0; i != argc; ++i)
413 argv[i] = args[i].empty() ? noarg : &args[i].front();
414 argv[argc] = nullptr;
416 int res = entry_point(argc, argv.get());
418 XBT_WARN("SMPI process did not return 0. Return value : %d", res);
419 if (smpi_exit_status == 0)
420 smpi_exit_status = res;
425 // TODO, remove the number of functions involved here
426 static smpi_entry_point_type smpi_resolve_function(void* handle)
428 smpi_fortran_entry_point_type entry_point_fortran = (smpi_fortran_entry_point_type)dlsym(handle, "user_main_");
429 if (entry_point_fortran != nullptr) {
430 return [entry_point_fortran](int argc, char** argv) {
431 smpi_process_init(&argc, &argv);
432 entry_point_fortran();
437 smpi_c_entry_point_type entry_point = (smpi_c_entry_point_type)dlsym(handle, "main");
438 if (entry_point != nullptr) {
442 return smpi_entry_point_type();
445 int smpi_main(const char* executable, int argc, char *argv[])
447 srand(SMPI_RAND_SEED);
449 if (getenv("SMPI_PRETEND_CC") != nullptr) {
450 /* Hack to ensure that smpicc can pretend to be a simple compiler. Particularly handy to pass it to the
451 * configuration tools */
457 SIMIX_global_init(&argc, argv);
458 MSG_init(&argc,argv);
460 SMPI_switch_data_segment = &smpi_switch_data_segment;
462 // TODO This will not be executed in the case where smpi_main is not called,
463 // e.g., not for smpi_msg_masterslave. This should be moved to another location
464 // that is always called -- maybe close to Actor::onCreation?
465 simgrid::s4u::Host::onCreation.connect([](simgrid::s4u::Host& host) {
466 host.extension_set(new simgrid::smpi::SmpiHost(&host));
469 // parse the platform file: get the host list
470 SIMIX_create_environment(argv[1]);
471 SIMIX_comm_set_copy_data_callback(smpi_comm_copy_buffer_callback);
474 if (smpi_privatize_global_variables == SmpiPrivStrategies::Dlopen) {
476 std::string executable_copy = executable;
478 // Prepare the copy of the binary (get its size)
479 struct stat fdin_stat;
480 stat(executable_copy.c_str(), &fdin_stat);
481 off_t fdin_size = fdin_stat.st_size;
482 static std::size_t rank = 0;
484 simix_global->default_function = [executable_copy, fdin_size](std::vector<std::string> args) {
485 return std::function<void()>([executable_copy, fdin_size, args] {
487 // Copy the dynamic library:
488 std::string target_executable = executable_copy
489 + "_" + std::to_string(getpid())
490 + "_" + std::to_string(rank++) + ".so";
492 int fdin = open(executable_copy.c_str(), O_RDONLY);
493 xbt_assert(fdin >= 0, "Cannot read from %s. Please make sure that the file exists and is executable.",
494 executable_copy.c_str());
495 int fdout = open(target_executable.c_str(), O_CREAT | O_RDWR, S_IRWXU);
496 xbt_assert(fdout >= 0, "Cannot write into %s", target_executable.c_str());
498 XBT_DEBUG("Copy %ld bytes into %s", static_cast<long>(fdin_size), target_executable.c_str());
500 ssize_t sent_size = sendfile(fdout, fdin, NULL, fdin_size);
501 xbt_assert(sent_size == fdin_size,
502 "Error while copying %s: only %zd bytes copied instead of %ld (errno: %d -- %s)",
503 target_executable.c_str(), sent_size, fdin_size, errno, strerror(errno));
505 const int bufsize = 1024 * 1024 * 4;
507 while (int got = read(fdin, buf, bufsize)) {
509 xbt_assert(errno == EINTR, "Cannot read from %s", executable_copy.c_str());
513 while (int done = write(fdout, p, todo)) {
515 xbt_assert(errno == EINTR, "Cannot write into %s", target_executable.c_str());
527 // Load the copy and resolve the entry point:
528 void* handle = dlopen(target_executable.c_str(), RTLD_LAZY | RTLD_LOCAL | RTLD_DEEPBIND);
529 int saved_errno = errno;
530 if (xbt_cfg_get_boolean("smpi/keep-temps") == false)
531 unlink(target_executable.c_str());
532 if (handle == nullptr)
533 xbt_die("dlopen failed: %s (errno: %d -- %s)", dlerror(), saved_errno, strerror(saved_errno));
534 smpi_entry_point_type entry_point = smpi_resolve_function(handle);
536 xbt_die("Could not resolve entry point");
538 smpi_run_entry_point(entry_point, args);
543 if (smpi_privatize_global_variables == SmpiPrivStrategies::Mmap)
544 smpi_prepare_global_memory_segment();
545 // Load the dynamic library and resolve the entry point:
546 void* handle = dlopen(executable, RTLD_LAZY | RTLD_LOCAL);
547 if (handle == nullptr)
548 xbt_die("dlopen failed for %s: %s (errno: %d -- %s)", executable, dlerror(), errno, strerror(errno));
549 smpi_entry_point_type entry_point = smpi_resolve_function(handle);
551 xbt_die("main not found in %s", executable);
552 if (smpi_privatize_global_variables == SmpiPrivStrategies::Mmap)
553 smpi_backup_global_memory_segment();
555 // Execute the same entry point for each simulated process:
556 simix_global->default_function = [entry_point](std::vector<std::string> args) {
557 return std::function<void()>([entry_point, args] {
558 smpi_run_entry_point(entry_point, args);
564 SIMIX_launch_application(argv[2]);
565 SMPI_app_instance_register(smpi_default_instance_name.c_str(), nullptr,
566 process_data.size()); // This call has a side effect on process_count...
567 MPI_COMM_WORLD = *smpi_deployment_comm_world(smpi_default_instance_name);
568 smpi_universe_size = process_count;
571 /* Clean IO before the run */
575 if (MC_is_active()) {
581 xbt_os_walltimer_stop(global_timer);
582 if (xbt_cfg_get_boolean("smpi/display-timing")){
583 double global_time = xbt_os_timer_elapsed(global_timer);
584 XBT_INFO("Simulated time: %g seconds. \n\n"
585 "The simulation took %g seconds (after parsing and platform setup)\n"
586 "%g seconds were actual computation of the application",
587 SIMIX_get_clock(), global_time , smpi_total_benched_time);
589 if (smpi_total_benched_time/global_time>=0.75)
590 XBT_INFO("More than 75%% of the time was spent inside the application code.\n"
591 "You may want to use sampling functions or trace replay to reduce this.");
594 smpi_global_destroy();
598 return smpi_exit_status;
601 // Called either directly from the user code, or from the code called by smpirun
603 simgrid::s4u::Actor::on_creation.connect([](simgrid::s4u::ActorPtr actor) {
604 if (not actor->is_daemon()) {
605 process_data.insert({actor, new simgrid::smpi::Process(actor, nullptr)});
608 simgrid::s4u::Actor::on_destruction.connect([](simgrid::s4u::ActorPtr actor) {
609 auto it = process_data.find(actor);
610 if (it != process_data.end()) {
612 process_data.erase(it);
618 smpi_check_options();
619 simgrid::s4u::onSimulationEnd.connect(TRACE_smpi_release);
622 void SMPI_finalize(){
623 smpi_global_destroy();
626 void smpi_mpi_init() {
627 if(smpi_init_sleep > 0)
628 simcall_process_sleep(smpi_init_sleep);
631 double smpi_mpi_wtime(){
633 if (smpi_process()->initialized() != 0 && smpi_process()->finalized() == 0 && smpi_process()->sampling() == 0) {
635 time = SIMIX_get_clock();
636 // to avoid deadlocks if used as a break condition, such as
637 // while (MPI_Wtime(...) < time_limit) {
640 // because the time will not normally advance when only calls to MPI_Wtime
641 // are made -> deadlock (MPI_Wtime never reaches the time limit)
642 if(smpi_wtime_sleep > 0)
643 simcall_process_sleep(smpi_wtime_sleep);
646 time = SIMIX_get_clock();