src/sim/eventq.cc

   1 /*
   2  * Copyright (c) 2000-2005 The Regents of The University of Michigan
   3  * Copyright (c) 2008 The Hewlett-Packard Development Company
   4  * Copyright (c) 2013 Advanced Micro Devices, Inc.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are
   9  * met: redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer;
  11  * redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution;
  14  * neither the name of the copyright holders nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * Authors: Steve Reinhardt
  31  *          Nathan Binkert
  32  *          Steve Raasch
  33  */
  34
  35 #include <cassert>
  36 #include <iostream>
  37 #include <string>
  38 #include <unordered_map>
  39 #include <vector>
  40
  41 #include "base/logging.hh"
  42 #include "base/trace.hh"
  43 #include "cpu/smt.hh"
  44 #include "debug/Checkpoint.hh"
  45 #include "sim/core.hh"
  46 #include "sim/eventq_impl.hh"
  47
  48 using namespace std;
  49
  50 Tick simQuantum = 0;
  51
  52 //
  53 // Main Event Queues
  54 //
  55 // Events on these queues are processed at the *beginning* of each
  56 // cycle, before the pipeline simulation is performed.
  57 //
  58 uint32_t numMainEventQueues = 0;
  59 vector<EventQueue *> mainEventQueue;
  60 __thread EventQueue *_curEventQueue = NULL;
  61 bool inParallelMode = false;
  62
  63 EventQueue *
  64 getEventQueue(uint32_t index)
  65 {
  66     while (numMainEventQueues <= index) {
  67         numMainEventQueues++;
  68         mainEventQueue.push_back(
  69             new EventQueue(csprintf("MainEventQueue-%d", index)));
  70     }
  71
  72     return mainEventQueue[index];
  73 }
  74
  75 #ifndef NDEBUG
  76 Counter Event::instanceCounter = 0;
  77 #endif
  78
  79 Event::~Event()
  80 {
  81     assert(!scheduled());
  82     flags = 0;
  83 }
  84
  85 const std::string
  86 Event::name() const
  87 {
  88 #ifndef NDEBUG
  89     return csprintf("Event_%d", instance);
  90 #else
  91     return csprintf("Event_%x", (uintptr_t)this);
  92 #endif
  93 }
  94
  95
  96 Event *
  97 Event::insertBefore(Event *event, Event *curr)
  98 {
  99     // Either way, event will be the top element in the 'in bin' list
 100     // which is the pointer we need in order to look into the list, so
 101     // we need to insert that into the bin list.
 102     if (!curr || *event < *curr) {
 103         // Insert the event before the current list since it is in the future.
 104         event->nextBin = curr;
 105         event->nextInBin = NULL;
 106     } else {
 107         // Since we're on the correct list, we need to point to the next list
 108         event->nextBin = curr->nextBin;  // curr->nextBin can now become stale
 109
 110         // Insert event at the top of the stack
 111         event->nextInBin = curr;
 112     }
 113
 114     return event;
 115 }
 116
 117 void
 118 EventQueue::insert(Event *event)
 119 {
 120     // Deal with the head case
 121     if (!head || *event <= *head) {
 122         head = Event::insertBefore(event, head);
 123         return;
 124     }
 125
 126     // Figure out either which 'in bin' list we are on, or where a new list
 127     // needs to be inserted
 128     Event *prev = head;
 129     Event *curr = head->nextBin;
 130     while (curr && *curr < *event) {
 131         prev = curr;
 132         curr = curr->nextBin;
 133     }
 134
 135     // Note: this operation may render all nextBin pointers on the
 136     // prev 'in bin' list stale (except for the top one)
 137     prev->nextBin = Event::insertBefore(event, curr);
 138 }
 139
 140 Event *
 141 Event::removeItem(Event *event, Event *top)
 142 {
 143     Event *curr = top;
 144     Event *next = top->nextInBin;
 145
 146     // if we removed the top item, we need to handle things specially
 147     // and just remove the top item, fixing up the next bin pointer of
 148     // the new top item
 149     if (event == top) {
 150         if (!next)
 151             return top->nextBin;
 152         next->nextBin = top->nextBin;
 153         return next;
 154     }
 155
 156     // Since we already checked the current element, we're going to
 157     // keep checking event against the next element.
 158     while (event != next) {
 159         if (!next)
 160             panic("event not found!");
 161
 162         curr = next;
 163         next = next->nextInBin;
 164     }
 165
 166     // remove next from the 'in bin' list since it's what we're looking for
 167     curr->nextInBin = next->nextInBin;
 168     return top;
 169 }
 170
 171 void
 172 EventQueue::remove(Event *event)
 173 {
 174     if (head == NULL)
 175         panic("event not found!");
 176
 177     assert(event->queue == this);
 178
 179     // deal with an event on the head's 'in bin' list (event has the same
 180     // time as the head)
 181     if (*head == *event) {
 182         head = Event::removeItem(event, head);
 183         return;
 184     }
 185
 186     // Find the 'in bin' list that this event belongs on
 187     Event *prev = head;
 188     Event *curr = head->nextBin;
 189     while (curr && *curr < *event) {
 190         prev = curr;
 191         curr = curr->nextBin;
 192     }
 193
 194     if (!curr || *curr != *event)
 195         panic("event not found!");
 196
 197     // curr points to the top item of the the correct 'in bin' list, when
 198     // we remove an item, it returns the new top item (which may be
 199     // unchanged)
 200     prev->nextBin = Event::removeItem(event, curr);
 201 }
 202
 203 Event *
 204 EventQueue::serviceOne()
 205 {
 206     std::lock_guard<EventQueue> lock(*this);
 207     Event *event = head;
 208     Event *next = head->nextInBin;
 209     event->flags.clear(Event::Scheduled);
 210
 211     if (next) {
 212         // update the next bin pointer since it could be stale
 213         next->nextBin = head->nextBin;
 214
 215         // pop the stack
 216         head = next;
 217     } else {
 218         // this was the only element on the 'in bin' list, so get rid of
 219         // the 'in bin' list and point to the next bin list
 220         head = head->nextBin;
 221     }
 222
 223     // handle action
 224     if (!event->squashed()) {
 225         // forward current cycle to the time when this event occurs.
 226         setCurTick(event->when());
 227
 228         event->process();
 229         if (event->isExitEvent()) {
 230             assert(!event->flags.isSet(Event::Managed) ||
 231                    !event->flags.isSet(Event::IsMainQueue)); // would be silly
 232             return event;
 233         }
 234     } else {
 235         event->flags.clear(Event::Squashed);
 236     }
 237
 238     event->release();
 239
 240     return NULL;
 241 }
 242
 243 void
 244 Event::serialize(CheckpointOut &cp) const
 245 {
 246     SERIALIZE_SCALAR(_when);
 247     SERIALIZE_SCALAR(_priority);
 248     short _flags = flags;
 249     SERIALIZE_SCALAR(_flags);
 250 }
 251
 252 void
 253 Event::unserialize(CheckpointIn &cp)
 254 {
 255     assert(!scheduled());
 256
 257     UNSERIALIZE_SCALAR(_when);
 258     UNSERIALIZE_SCALAR(_priority);
 259
 260     FlagsType _flags;
 261     UNSERIALIZE_SCALAR(_flags);
 262
 263     // Old checkpoints had no concept of the Initialized flag
 264     // so restoring from old checkpoints always fail.
 265     // Events are initialized on construction but original code
 266     // "flags = _flags" would just overwrite the initialization.
 267     // So, read in the checkpoint flags, but then set the Initialized
 268     // flag on top of it in order to avoid failures.
 269     assert(initialized());
 270     flags = _flags;
 271     flags.set(Initialized);
 272
 273     // need to see if original event was in a scheduled, unsquashed
 274     // state, but don't want to restore those flags in the current
 275     // object itself (since they aren't immediately true)
 276     if (flags.isSet(Scheduled) && !flags.isSet(Squashed)) {
 277         flags.clear(Squashed | Scheduled);
 278     } else {
 279         DPRINTF(Checkpoint, "Event '%s' need to be scheduled @%d\n",
 280                 name(), _when);
 281     }
 282 }
 283
 284 void
 285 EventQueue::checkpointReschedule(Event *event)
 286 {
 287     // It's safe to call insert() directly here since this method
 288     // should only be called when restoring from a checkpoint (which
 289     // happens before thread creation).
 290     if (event->flags.isSet(Event::Scheduled))
 291         insert(event);
 292 }
 293 void
 294 EventQueue::dump() const
 295 {
 296     cprintf("============================================================\n");
 297     cprintf("EventQueue Dump  (cycle %d)\n", curTick());
 298     cprintf("------------------------------------------------------------\n");
 299
 300     if (empty())
 301         cprintf("<No Events>\n");
 302     else {
 303         Event *nextBin = head;
 304         while (nextBin) {
 305             Event *nextInBin = nextBin;
 306             while (nextInBin) {
 307                 nextInBin->dump();
 308                 nextInBin = nextInBin->nextInBin;
 309             }
 310
 311             nextBin = nextBin->nextBin;
 312         }
 313     }
 314
 315     cprintf("============================================================\n");
 316 }
 317
 318 bool
 319 EventQueue::debugVerify() const
 320 {
 321     std::unordered_map<long, bool> map;
 322
 323     Tick time = 0;
 324     short priority = 0;
 325
 326     Event *nextBin = head;
 327     while (nextBin) {
 328         Event *nextInBin = nextBin;
 329         while (nextInBin) {
 330             if (nextInBin->when() < time) {
 331                 cprintf("time goes backwards!");
 332                 nextInBin->dump();
 333                 return false;
 334             } else if (nextInBin->when() == time &&
 335                        nextInBin->priority() < priority) {
 336                 cprintf("priority inverted!");
 337                 nextInBin->dump();
 338                 return false;
 339             }
 340
 341             if (map[reinterpret_cast<long>(nextInBin)]) {
 342                 cprintf("Node already seen");
 343                 nextInBin->dump();
 344                 return false;
 345             }
 346             map[reinterpret_cast<long>(nextInBin)] = true;
 347
 348             time = nextInBin->when();
 349             priority = nextInBin->priority();
 350
 351             nextInBin = nextInBin->nextInBin;
 352         }
 353
 354         nextBin = nextBin->nextBin;
 355     }
 356
 357     return true;
 358 }
 359
 360 Event*
 361 EventQueue::replaceHead(Event* s)
 362 {
 363     Event* t = head;
 364     head = s;
 365     return t;
 366 }
 367
 368 void
 369 dumpMainQueue()
 370 {
 371     for (uint32_t i = 0; i < numMainEventQueues; ++i) {
 372         mainEventQueue[i]->dump();
 373     }
 374 }
 375
 376
 377 const char *
 378 Event::description() const
 379 {
 380     return "generic";
 381 }
 382
 383 void
 384 Event::trace(const char *action)
 385 {
 386     // This DPRINTF is unconditional because calls to this function
 387     // are protected by an 'if (DTRACE(Event))' in the inlined Event
 388     // methods.
 389     //
 390     // This is just a default implementation for derived classes where
 391     // it's not worth doing anything special.  If you want to put a
 392     // more informative message in the trace, override this method on
 393     // the particular subclass where you have the information that
 394     // needs to be printed.
 395     DPRINTF_UNCONDITIONAL(Event, "%s event %s @ %d\n",
 396             description(), action, when());
 397 }
 398
 399 void
 400 Event::dump() const
 401 {
 402     cprintf("Event %s (%s)\n", name(), description());
 403     cprintf("Flags: %#x\n", flags);
 404 #ifdef EVENTQ_DEBUG
 405     cprintf("Created: %d\n", whenCreated);
 406 #endif
 407     if (scheduled()) {
 408 #ifdef EVENTQ_DEBUG
 409         cprintf("Scheduled at  %d\n", whenScheduled);
 410 #endif
 411         cprintf("Scheduled for %d, priority %d\n", when(), _priority);
 412     } else {
 413         cprintf("Not Scheduled\n");
 414     }
 415 }
 416
 417 EventQueue::EventQueue(const string &n)
 418     : objName(n), head(NULL), _curTick(0)
 419 {
 420 }
 421
 422 void
 423 EventQueue::asyncInsert(Event *event)
 424 {
 425     async_queue_mutex.lock();
 426     async_queue.push_back(event);
 427     async_queue_mutex.unlock();
 428 }
 429
 430 void
 431 EventQueue::handleAsyncInsertions()
 432 {
 433     assert(this == curEventQueue());
 434     async_queue_mutex.lock();
 435
 436     while (!async_queue.empty()) {
 437         insert(async_queue.front());
 438         async_queue.pop_front();
 439     }
 440
 441     async_queue_mutex.unlock();
 442 }