eventq.hh revision 5577
1/*
2 * Copyright (c) 2000-2005 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Steve Reinhardt
29 *          Nathan Binkert
30 */
31
32/* @file
33 * EventQueue interfaces
34 */
35
36#ifndef __SIM_EVENTQ_HH__
37#define __SIM_EVENTQ_HH__
38
39#include <algorithm>
40#include <cassert>
41#include <climits>
42#include <map>
43#include <string>
44#include <vector>
45
46#include "base/fast_alloc.hh"
47#include "base/misc.hh"
48#include "base/trace.hh"
49#include "sim/serialize.hh"
50#include "sim/host.hh"
51
52class EventQueue;       // forward declaration
53
54//////////////////////
55//
56// Main Event Queue
57//
58// Events on this queue are processed at the *beginning* of each
59// cycle, before the pipeline simulation is performed.
60//
61// defined in eventq.cc
62//
63//////////////////////
64extern EventQueue mainEventQueue;
65
66/*
67 * An item on an event queue.  The action caused by a given
68 * event is specified by deriving a subclass and overriding the
69 * process() member function.
70 *
71 * Caution, the order of members is chosen to maximize data packing.
72 */
73class Event : public Serializable, public FastAlloc
74{
75    friend class EventQueue;
76
77  private:
78    // The event queue is now a linked list of linked lists.  The
79    // 'nextBin' pointer is to find the bin, where a bin is defined as
80    // when+priority.  All events in the same bin will be stored in a
81    // second linked list (a stack) maintained by the 'nextInBin'
82    // pointer.  The list will be accessed in LIFO order.  The end
83    // result is that the insert/removal in 'nextBin' is
84    // linear/constant, and the lookup/removal in 'nextInBin' is
85    // constant/constant.  Hopefully this is a significant improvement
86    // over the current fully linear insertion.
87    Event *nextBin;
88    Event *nextInBin;
89
90    friend Event *insertBefore(Event *event, Event *curr);
91    friend Event *removeItem(Event *event, Event *last);
92
93    /// queue to which this event belongs (though it may or may not be
94    /// scheduled on this queue yet)
95    EventQueue *_queue;
96
97    Tick _when;         //!< timestamp when event should be processed
98    short _priority;    //!< event priority
99    short _flags;
100
101#ifndef NDEBUG
102    /// Global counter to generate unique IDs for Event instances
103    static Counter instanceCounter;
104
105    /// This event's unique ID.  We can also use pointer values for
106    /// this but they're not consistent across runs making debugging
107    /// more difficult.  Thus we use a global counter value when
108    /// debugging.
109    Counter instance;
110#endif
111
112#ifdef EVENTQ_DEBUG
113    Tick whenCreated;   //!< time created
114    Tick whenScheduled; //!< time scheduled
115#endif
116
117  protected:
118    void
119    setWhen(Tick when)
120    {
121        _when = when;
122#ifdef EVENTQ_DEBUG
123        whenScheduled = curTick;
124#endif
125    }
126
127  protected:
128    enum Flags {
129        None = 0x0,
130        Squashed = 0x1,
131        Scheduled = 0x2,
132        AutoDelete = 0x4,
133        AutoSerialize = 0x8,
134        IsExitEvent = 0x10
135    };
136
137    bool getFlags(Flags f) const { return (_flags & f) == f; }
138    void setFlags(Flags f) { _flags |= f; }
139    void clearFlags(Flags f) { _flags &= ~f; }
140
141  protected:
142    EventQueue *queue() const { return _queue; }
143
144    // This function isn't really useful if TRACING_ON is not defined
145    virtual void trace(const char *action);     //!< trace event activity
146
147  public:
148    /// Event priorities, to provide tie-breakers for events scheduled
149    /// at the same cycle.  Most events are scheduled at the default
150    /// priority; these values are used to control events that need to
151    /// be ordered within a cycle.
152    enum Priority {
153        /// Minimum priority
154        Minimum_Pri             = SHRT_MIN,
155
156        /// If we enable tracing on a particular cycle, do that as the
157        /// very first thing so we don't miss any of the events on
158        /// that cycle (even if we enter the debugger).
159        Trace_Enable_Pri        = -101,
160
161        /// Breakpoints should happen before anything else (except
162        /// enabling trace output), so we don't miss any action when
163        /// debugging.
164        Debug_Break_Pri         = -100,
165
166        /// CPU switches schedule the new CPU's tick event for the
167        /// same cycle (after unscheduling the old CPU's tick event).
168        /// The switch needs to come before any tick events to make
169        /// sure we don't tick both CPUs in the same cycle.
170        CPU_Switch_Pri          =   -31,
171
172        /// For some reason "delayed" inter-cluster writebacks are
173        /// scheduled before regular writebacks (which have default
174        /// priority).  Steve?
175        Delayed_Writeback_Pri   =   -1,
176
177        /// Default is zero for historical reasons.
178        Default_Pri             =    0,
179
180        /// Serailization needs to occur before tick events also, so
181        /// that a serialize/unserialize is identical to an on-line
182        /// CPU switch.
183        Serialize_Pri           =   32,
184
185        /// CPU ticks must come after other associated CPU events
186        /// (such as writebacks).
187        CPU_Tick_Pri            =   50,
188
189        /// Statistics events (dump, reset, etc.) come after
190        /// everything else, but before exit.
191        Stat_Event_Pri          =   90,
192
193        /// Progress events come at the end.
194        Progress_Event_Pri      =   95,
195
196        /// If we want to exit on this cycle, it's the very last thing
197        /// we do.
198        Sim_Exit_Pri            =  100,
199
200        /// Maximum priority
201        Maximum_Pri             = SHRT_MAX
202    };
203
204    /*
205     * Event constructor
206     * @param queue that the event gets scheduled on
207     */
208    Event(EventQueue *q, Priority p = Default_Pri)
209        : nextBin(NULL), nextInBin(NULL), _queue(q), _priority(p), _flags(None)
210    {
211#ifndef NDEBUG
212        instance = ++instanceCounter;
213#endif
214#ifdef EVENTQ_DEBUG
215        whenCreated = curTick;
216        whenScheduled = 0;
217#endif
218    }
219
220    virtual
221    ~Event()
222    {
223    }
224
225    virtual const std::string
226    name() const
227    {
228#ifndef NDEBUG
229        return csprintf("Event_%d", instance);
230#else
231        return csprintf("Event_%x", (uintptr_t)this);
232#endif
233    }
234
235    /// Return a C string describing the event.  This string should
236    /// *not* be dynamically allocated; just a const char array
237    /// describing the event class.
238    virtual const char *description() const;
239
240    /// Dump the current event data
241    void dump() const;
242
243  public:
244    /*
245     * This member function is invoked when the event is processed
246     * (occurs).  There is no default implementation; each subclass
247     * must provide its own implementation.  The event is not
248     * automatically deleted after it is processed (to allow for
249     * statically allocated event objects).
250     *
251     * If the AutoDestroy flag is set, the object is deleted once it
252     * is processed.
253     */
254    virtual void process() = 0;
255
256    /// Determine if the current event is scheduled
257    bool scheduled() const { return getFlags(Scheduled); }
258
259    /// Schedule the event with the current priority or default priority
260    void schedule(Tick t);
261
262    /// Reschedule the event with the current priority
263    // always parameter means to schedule if not already scheduled
264    void reschedule(Tick t, bool always = false);
265
266    /// Remove the event from the current schedule
267    void deschedule();
268
269    /// Squash the current event
270    void squash() { setFlags(Squashed); }
271
272    /// Check whether the event is squashed
273    bool squashed() const { return getFlags(Squashed); }
274
275    /// See if this is a SimExitEvent (without resorting to RTTI)
276    bool isExitEvent() const { return getFlags(IsExitEvent); }
277
278    /// Get the time that the event is scheduled
279    Tick when() const { return _when; }
280
281    /// Get the event priority
282    int priority() const { return _priority; }
283
284    struct priority_compare
285        : public std::binary_function<Event *, Event *, bool>
286    {
287        bool
288        operator()(const Event *l, const Event *r) const
289        {
290            return l->when() >= r->when() || l->priority() >= r->priority();
291        }
292    };
293
294    virtual void serialize(std::ostream &os);
295    virtual void unserialize(Checkpoint *cp, const std::string &section);
296};
297
298template <class T, void (T::* F)()>
299void
300DelayFunction(Tick when, T *object)
301{
302    class DelayEvent : public Event
303    {
304      private:
305        T *object;
306
307      public:
308        DelayEvent(Tick when, T *o)
309            : Event(&mainEventQueue), object(o)
310            { setFlags(this->AutoDestroy); schedule(when); }
311        void process() { (object->*F)(); }
312        const char *description() const { return "delay"; }
313    };
314
315    new DelayEvent(when, object);
316}
317
318template <class T, void (T::* F)()>
319class EventWrapper : public Event
320{
321  private:
322    T *object;
323
324  public:
325    EventWrapper(T *obj, bool del = false,
326                 EventQueue *q = &mainEventQueue,
327                 Priority p = Default_Pri)
328        : Event(q, p), object(obj)
329    {
330        if (del)
331            setFlags(AutoDelete);
332    }
333
334    EventWrapper(T *obj, Tick t, bool del = false,
335                 EventQueue *q = &mainEventQueue,
336                 Priority p = Default_Pri)
337        : Event(q, p), object(obj)
338    {
339        if (del)
340            setFlags(AutoDelete);
341        schedule(t);
342    }
343
344    void process() { (object->*F)(); }
345};
346
347/*
348 * Queue of events sorted in time order
349 */
350class EventQueue : public Serializable
351{
352  protected:
353    std::string objName;
354
355  private:
356    Event *head;
357
358    void insert(Event *event);
359    void remove(Event *event);
360
361  public:
362
363    // constructor
364    EventQueue(const std::string &n)
365        : objName(n), head(NULL)
366    {}
367
368    virtual const std::string name() const { return objName; }
369
370    // schedule the given event on this queue
371    void schedule(Event *ev, Tick when);
372    void deschedule(Event *ev);
373    void reschedule(Event *ev, Tick when);
374
375    Tick nextTick() const { return head->when(); }
376    Event *serviceOne();
377
378    // process all events up to the given timestamp.  we inline a
379    // quick test to see if there are any events to process; if so,
380    // call the internal out-of-line version to process them all.
381    void
382    serviceEvents(Tick when)
383    {
384        while (!empty()) {
385            if (nextTick() > when)
386                break;
387
388            /**
389             * @todo this assert is a good bug catcher.  I need to
390             * make it true again.
391             */
392            //assert(head->when() >= when && "event scheduled in the past");
393            serviceOne();
394        }
395    }
396
397    // default: process all events up to 'now' (curTick)
398    void serviceEvents() { serviceEvents(curTick); }
399
400    // return true if no events are queued
401    bool empty() const { return head == NULL; }
402
403    void dump() const;
404
405    Tick nextEventTime() { return empty() ? curTick : head->when(); }
406
407    bool debugVerify() const;
408
409    virtual void serialize(std::ostream &os);
410    virtual void unserialize(Checkpoint *cp, const std::string &section);
411};
412
413
414//////////////////////
415//
416// inline functions
417//
418// can't put these inside declaration due to circular dependence
419// between Event and EventQueue classes.
420//
421//////////////////////
422
423// schedule at specified time (place on event queue specified via
424// constructor)
425inline void
426Event::schedule(Tick when)
427{
428    _queue->schedule(this, when);
429}
430
431inline void
432Event::deschedule()
433{
434    _queue->deschedule(this);
435}
436
437inline void
438Event::reschedule(Tick when, bool always)
439{
440    if (scheduled()) {
441        _queue->reschedule(this, when);
442    } else {
443        assert(always);
444        _queue->schedule(this, when);
445    }
446}
447
448inline bool
449operator<(const Event &l, const Event &r)
450{
451    return l.when() < r.when() ||
452        (l.when() == r.when() && l.priority() < r.priority());
453}
454
455inline bool
456operator>(const Event &l, const Event &r)
457{
458    return l.when() > r.when() ||
459        (l.when() == r.when() && l.priority() > r.priority());
460}
461
462inline bool
463operator<=(const Event &l, const Event &r)
464{
465    return l.when() < r.when() ||
466        (l.when() == r.when() && l.priority() <= r.priority());
467}
468inline bool
469operator>=(const Event &l, const Event &r)
470{
471    return l.when() > r.when() ||
472        (l.when() == r.when() && l.priority() >= r.priority());
473}
474
475inline bool
476operator==(const Event &l, const Event &r)
477{
478    return l.when() == r.when() && l.priority() == r.priority();
479}
480
481inline bool
482operator!=(const Event &l, const Event &r)
483{
484    return l.when() != r.when() || l.priority() != r.priority();
485}
486
487inline void
488EventQueue::schedule(Event *event, Tick when)
489{
490    assert(when >= curTick);
491    assert(!event->scheduled());
492
493    event->setWhen(when);
494    insert(event);
495    event->setFlags(Event::Scheduled);
496
497    if (DTRACE(Event))
498        event->trace("scheduled");
499}
500
501inline void
502EventQueue::deschedule(Event *event)
503{
504    assert(event->scheduled());
505
506    remove(event);
507
508    event->clearFlags(Event::Squashed);
509    event->clearFlags(Event::Scheduled);
510
511    if (event->getFlags(Event::AutoDelete))
512        delete event;
513
514    if (DTRACE(Event))
515        event->trace("descheduled");
516}
517
518inline void
519EventQueue::reschedule(Event *event, Tick when)
520{
521    assert(when >= curTick);
522    assert(event->scheduled());
523
524    remove(event);
525    event->setWhen(when);
526    insert(event);
527    event->clearFlags(Event::Squashed);
528
529    if (DTRACE(Event))
530        event->trace("rescheduled");
531}
532
533#endif // __SIM_EVENTQ_HH__
534