eventq.cc revision 7823:dac01f14f20f
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
46using 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//
54EventQueue mainEventQueue("Main Event Queue");
55
56#ifndef NDEBUG
57Counter Event::instanceCounter = 0;
58#endif
59
60Event::~Event()
61{
62    assert(!scheduled());
63    flags = 0;
64}
65
66const std::string
67Event::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
77Event *
78Event::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
98void
99EventQueue::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
121Event *
122Event::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
152void
153EventQueue::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
182Event *
183EventQueue::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
218void
219Event::serialize(std::ostream &os)
220{
221    SERIALIZE_SCALAR(_when);
222    SERIALIZE_SCALAR(_priority);
223    short _flags = flags;
224    SERIALIZE_SCALAR(_flags);
225}
226
227void
228Event::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
261void
262EventQueue::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
292void
293EventQueue::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
308void
309EventQueue::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
333bool
334EventQueue::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
375void
376dumpMainQueue()
377{
378    mainEventQueue.dump();
379}
380
381
382const char *
383Event::description() const
384{
385    return "generic";
386}
387
388void
389Event::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
403void
404Event::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
421EventQueue::EventQueue(const string &n)
422    : objName(n), head(NULL)
423{}
424