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  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are
   8  * met: redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer;
  10  * redistributions in binary form must reproduce the above copyright
  11  * notice, this list of conditions and the following disclaimer in the
  12  * documentation and/or other materials provided with the distribution;
  13  * neither the name of the copyright holders nor the names of its
  14  * contributors may be used to endorse or promote products derived from
  15  * this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  *
  29  * Authors: Steve Reinhardt
  30  *          Nathan Binkert
  31  *          Steve Raasch
  32  */
  33
  34 #include <cassert>
  35 #include <iostream>
  36 #include <string>
  37 #include <vector>
  38
  39 #include "base/hashmap.hh"
  40 #include "base/misc.hh"
  41 #include "base/trace.hh"
  42 #include "cpu/smt.hh"
  43 #include "sim/core.hh"
  44 #include "sim/eventq.hh"
  45
  46 using namespace std;
  47
  48 //
  49 // Main Event Queue
  50 //
  51 // Events on this queue are processed at the *beginning* of each
  52 // cycle, before the pipeline simulation is performed.
  53 //
  54 EventQueue mainEventQueue("Main Event Queue");
  55
  56 #ifndef NDEBUG
  57 Counter Event::instanceCounter = 0;
  58 #endif
  59
  60 Event::~Event()
  61 {
  62     assert(!scheduled());
  63     flags = 0;
  64 }
  65
  66 const std::string
  67 Event::name() const
  68 {
  69 #ifndef NDEBUG
  70     return csprintf("Event_%d", instance);
  71 #else
  72     return csprintf("Event_%x", (uintptr_t)this);
  73 #endif
  74 }
  75
  76
  77 Event *
  78 Event::insertBefore(Event *event, Event *curr)
  79 {
  80     // Either way, event will be the top element in the 'in bin' list
  81     // which is the pointer we need in order to look into the list, so
  82     // we need to insert that into the bin list.
  83     if (!curr || *event < *curr) {
  84         // Insert the event before the current list since it is in the future.
  85         event->nextBin = curr;
  86         event->nextInBin = NULL;
  87     } else {
  88         // Since we're on the correct list, we need to point to the next list
  89         event->nextBin = curr->nextBin;  // curr->nextBin can now become stale
  90
  91         // Insert event at the top of the stack
  92         event->nextInBin = curr;
  93     }
  94
  95     return event;
  96 }
  97
  98 void
  99 EventQueue::insert(Event *event)
 100 {
 101     // Deal with the head case
 102     if (!head || *event <= *head) {
 103         head = Event::insertBefore(event, head);
 104         return;
 105     }
 106
 107     // Figure out either which 'in bin' list we are on, or where a new list
 108     // needs to be inserted
 109     Event *prev = head;
 110     Event *curr = head->nextBin;
 111     while (curr && *curr < *event) {
 112         prev = curr;
 113         curr = curr->nextBin;
 114     }
 115
 116     // Note: this operation may render all nextBin pointers on the
 117     // prev 'in bin' list stale (except for the top one)
 118     prev->nextBin = Event::insertBefore(event, curr);
 119 }
 120
 121 Event *
 122 Event::removeItem(Event *event, Event *top)
 123 {
 124     Event *curr = top;
 125     Event *next = top->nextInBin;
 126
 127     // if we removed the top item, we need to handle things specially
 128     // and just remove the top item, fixing up the next bin pointer of
 129     // the new top item
 130     if (event == top) {
 131         if (!next)
 132             return top->nextBin;
 133         next->nextBin = top->nextBin;
 134         return next;
 135     }
 136
 137     // Since we already checked the current element, we're going to
 138     // keep checking event against the next element.
 139     while (event != next) {
 140         if (!next)
 141             panic("event not found!");
 142
 143         curr = next;
 144         next = next->nextInBin;
 145     }
 146
 147     // remove next from the 'in bin' list since it's what we're looking for
 148     curr->nextInBin = next->nextInBin;
 149     return top;
 150 }
 151
 152 void
 153 EventQueue::remove(Event *event)
 154 {
 155     if (head == NULL)
 156         panic("event not found!");
 157
 158     // deal with an event on the head's 'in bin' list (event has the same
 159     // time as the head)
 160     if (*head == *event) {
 161         head = Event::removeItem(event, head);
 162         return;
 163     }
 164
 165     // Find the 'in bin' list that this event belongs on
 166     Event *prev = head;
 167     Event *curr = head->nextBin;
 168     while (curr && *curr < *event) {
 169         prev = curr;
 170         curr = curr->nextBin;
 171     }
 172
 173     if (!curr || *curr != *event)
 174         panic("event not found!");
 175
 176     // curr points to the top item of the the correct 'in bin' list, when
 177     // we remove an item, it returns the new top item (which may be
 178     // unchanged)
 179     prev->nextBin = Event::removeItem(event, curr);
 180 }
 181
 182 Event *
 183 EventQueue::serviceOne()
 184 {
 185     Event *event = head;
 186     Event *next = head->nextInBin;
 187     event->flags.clear(Event::Scheduled);
 188
 189     if (next) {
 190         // update the next bin pointer since it could be stale
 191         next->nextBin = head->nextBin;
 192
 193         // pop the stack
 194         head = next;
 195     } else {
 196         // this was the only element on the 'in bin' list, so get rid of
 197         // the 'in bin' list and point to the next bin list
 198         head = head->nextBin;
 199     }
 200
 201     // handle action
 202     if (!event->squashed()) {
 203         event->process();
 204         if (event->isExitEvent()) {
 205             assert(!event->flags.isSet(Event::AutoDelete)); // would be silly
 206             return event;
 207         }
 208     } else {
 209         event->flags.clear(Event::Squashed);
 210     }
 211
 212     if (event->flags.isSet(Event::AutoDelete) && !event->scheduled())
 213         delete event;
 214
 215     return NULL;
 216 }
 217
 218 void
 219 Event::serialize(std::ostream &os)
 220 {
 221     SERIALIZE_SCALAR(_when);
 222     SERIALIZE_SCALAR(_priority);
 223     short _flags = flags;
 224     SERIALIZE_SCALAR(_flags);
 225 }
 226
 227 void
 228 Event::unserialize(Checkpoint *cp, const string &section)
 229 {
 230     if (scheduled())
 231         mainEventQueue.deschedule(this);
 232
 233     UNSERIALIZE_SCALAR(_when);
 234     UNSERIALIZE_SCALAR(_priority);
 235
 236     short _flags;
 237     UNSERIALIZE_SCALAR(_flags);
 238
 239     // Old checkpoints had no concept of the Initialized flag
 240     // so restoring from old checkpoints always fail.
 241     // Events are initialized on construction but original code
 242     // "flags = _flags" would just overwrite the initialization.
 243     // So, read in the checkpoint flags, but then set the Initialized
 244     // flag on top of it in order to avoid failures.
 245     assert(initialized());
 246     flags = _flags;
 247     flags.set(Initialized);
 248
 249     // need to see if original event was in a scheduled, unsquashed
 250     // state, but don't want to restore those flags in the current
 251     // object itself (since they aren't immediately true)
 252     bool wasScheduled = flags.isSet(Scheduled) && !flags.isSet(Squashed);
 253     flags.clear(Squashed | Scheduled);
 254
 255     if (wasScheduled) {
 256         DPRINTF(Config, "rescheduling at %d\n", _when);
 257         mainEventQueue.schedule(this, _when);
 258     }
 259 }
 260
 261 void
 262 EventQueue::serialize(ostream &os)
 263 {
 264     std::list<Event *> eventPtrs;
 265
 266     int numEvents = 0;
 267     Event *nextBin = head;
 268     while (nextBin) {
 269         Event *nextInBin = nextBin;
 270
 271         while (nextInBin) {
 272             if (nextInBin->flags.isSet(Event::AutoSerialize)) {
 273                 eventPtrs.push_back(nextInBin);
 274                 paramOut(os, csprintf("event%d", numEvents++),
 275                          nextInBin->name());
 276             }
 277             nextInBin = nextInBin->nextInBin;
 278         }
 279
 280         nextBin = nextBin->nextBin;
 281     }
 282
 283     SERIALIZE_SCALAR(numEvents);
 284
 285     for (std::list<Event *>::iterator it = eventPtrs.begin();
 286          it != eventPtrs.end(); ++it) {
 287         (*it)->nameOut(os);
 288         (*it)->serialize(os);
 289     }
 290 }
 291
 292 void
 293 EventQueue::unserialize(Checkpoint *cp, const std::string &section)
 294 {
 295     int numEvents;
 296     UNSERIALIZE_SCALAR(numEvents);
 297
 298     std::string eventName;
 299     for (int i = 0; i < numEvents; i++) {
 300         // get the pointer value associated with the event
 301         paramIn(cp, section, csprintf("event%d", i), eventName);
 302
 303         // create the event based on its pointer value
 304         Serializable::create(cp, eventName);
 305     }
 306 }
 307
 308 void
 309 EventQueue::dump() const
 310 {
 311     cprintf("============================================================\n");
 312     cprintf("EventQueue Dump  (cycle %d)\n", curTick);
 313     cprintf("------------------------------------------------------------\n");
 314
 315     if (empty())
 316         cprintf("<No Events>\n");
 317     else {
 318         Event *nextBin = head;
 319         while (nextBin) {
 320             Event *nextInBin = nextBin;
 321             while (nextInBin) {
 322                 nextInBin->dump();
 323                 nextInBin = nextInBin->nextInBin;
 324             }
 325
 326             nextBin = nextBin->nextBin;
 327         }
 328     }
 329
 330     cprintf("============================================================\n");
 331 }
 332
 333 bool
 334 EventQueue::debugVerify() const
 335 {
 336     m5::hash_map<long, bool> map;
 337
 338     Tick time = 0;
 339     short priority = 0;
 340
 341     Event *nextBin = head;
 342     while (nextBin) {
 343         Event *nextInBin = nextBin;
 344         while (nextInBin) {
 345             if (nextInBin->when() < time) {
 346                 cprintf("time goes backwards!");
 347                 nextInBin->dump();
 348                 return false;
 349             } else if (nextInBin->when() == time &&
 350                        nextInBin->priority() < priority) {
 351                 cprintf("priority inverted!");
 352                 nextInBin->dump();
 353                 return false;
 354             }
 355
 356             if (map[reinterpret_cast<long>(nextInBin)]) {
 357                 cprintf("Node already seen");
 358                 nextInBin->dump();
 359                 return false;
 360             }
 361             map[reinterpret_cast<long>(nextInBin)] = true;
 362
 363             time = nextInBin->when();
 364             priority = nextInBin->priority();
 365
 366             nextInBin = nextInBin->nextInBin;
 367         }
 368
 369         nextBin = nextBin->nextBin;
 370     }
 371
 372     return true;
 373 }
 374
 375 void
 376 dumpMainQueue()
 377 {
 378     mainEventQueue.dump();
 379 }
 380
 381
 382 const char *
 383 Event::description() const
 384 {
 385     return "generic";
 386 }
 387
 388 void
 389 Event::trace(const char *action)
 390 {
 391     // This DPRINTF is unconditional because calls to this function
 392     // are protected by an 'if (DTRACE(Event))' in the inlined Event
 393     // methods.
 394     //
 395     // This is just a default implementation for derived classes where
 396     // it's not worth doing anything special.  If you want to put a
 397     // more informative message in the trace, override this method on
 398     // the particular subclass where you have the information that
 399     // needs to be printed.
 400     DPRINTFN("%s event %s @ %d\n", description(), action, when());
 401 }
 402
 403 void
 404 Event::dump() const
 405 {
 406     cprintf("Event %s (%s)\n", name(), description());
 407     cprintf("Flags: %#x\n", flags);
 408 #ifdef EVENTQ_DEBUG
 409     cprintf("Created: %d\n", whenCreated);
 410 #endif
 411     if (scheduled()) {
 412 #ifdef EVENTQ_DEBUG
 413         cprintf("Scheduled at  %d\n", whenScheduled);
 414 #endif
 415         cprintf("Scheduled for %d, priority %d\n", when(), _priority);
 416     } else {
 417         cprintf("Not Scheduled\n");
 418     }
 419 }
 420
 421 EventQueue::EventQueue(const string &n)
 422     : objName(n), head(NULL)
 423 {}