eventq.hh revision 5336
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 <assert.h>
40
41#include <algorithm>
42#include <map>
43#include <string>
44#include <vector>
45
46#include "sim/host.hh"	// for Tick
47
48#include "base/fast_alloc.hh"
49#include "base/misc.hh"
50#include "base/trace.hh"
51#include "sim/serialize.hh"
52
53class EventQueue;	// forward declaration
54
55//////////////////////
56//
57// Main Event Queue
58//
59// Events on this queue are processed at the *beginning* of each
60// cycle, before the pipeline simulation is performed.
61//
62// defined in eventq.cc
63//
64//////////////////////
65extern EventQueue mainEventQueue;
66
67
68/*
69 * An item on an event queue.  The action caused by a given
70 * event is specified by deriving a subclass and overriding the
71 * process() member function.
72 */
73class Event : public Serializable, public FastAlloc
74{
75    friend class EventQueue;
76
77  private:
78
79#ifndef NDEBUG
80    /// Global counter to generate unique IDs for Event instances
81    static Counter instanceCounter;
82
83    /// This event's unique ID.  We can also use pointer values for
84    /// this but they're not consistent across runs making debugging
85    /// more difficult.  Thus we use a global counter value when
86    /// debugging.
87    Counter instanceId;
88#endif // NDEBUG
89
90    /// queue to which this event belongs (though it may or may not be
91    /// scheduled on this queue yet)
92    EventQueue *queue;
93
94    Event *next;
95
96    Tick _when;	//!< timestamp when event should be processed
97    int _priority;	//!< event priority
98    char _flags;
99
100  protected:
101    enum Flags {
102        None = 0x0,
103        Squashed = 0x1,
104        Scheduled = 0x2,
105        AutoDelete = 0x4,
106        AutoSerialize = 0x8,
107        IsExitEvent = 0x10
108    };
109
110    bool getFlags(Flags f) const { return (_flags & f) == f; }
111    void setFlags(Flags f) { _flags |= f; }
112    void clearFlags(Flags f) { _flags &= ~f; }
113
114  protected:
115    EventQueue *theQueue() const { return queue; }
116
117#if TRACING_ON
118    Tick when_created;	//!< Keep track of creation time For debugging
119    Tick when_scheduled;	//!< Keep track of creation time For debugging
120
121    virtual void trace(const char *action);	//!< trace event activity
122#else
123    void trace(const char *) {}
124#endif
125
126    unsigned annotated_value;
127
128  public:
129
130    /// Event priorities, to provide tie-breakers for events scheduled
131    /// at the same cycle.  Most events are scheduled at the default
132    /// priority; these values are used to control events that need to
133    /// be ordered within a cycle.
134    enum Priority {
135        /// If we enable tracing on a particular cycle, do that as the
136        /// very first thing so we don't miss any of the events on
137        /// that cycle (even if we enter the debugger).
138        Trace_Enable_Pri        = -101,
139
140        /// Breakpoints should happen before anything else (except
141        /// enabling trace output), so we don't miss any action when
142        /// debugging.
143        Debug_Break_Pri		= -100,
144
145        /// CPU switches schedule the new CPU's tick event for the
146        /// same cycle (after unscheduling the old CPU's tick event).
147        /// The switch needs to come before any tick events to make
148        /// sure we don't tick both CPUs in the same cycle.
149        CPU_Switch_Pri		=   -31,
150
151        /// For some reason "delayed" inter-cluster writebacks are
152        /// scheduled before regular writebacks (which have default
153        /// priority).  Steve?
154        Delayed_Writeback_Pri	=   -1,
155
156        /// Default is zero for historical reasons.
157        Default_Pri		=    0,
158
159        /// Serailization needs to occur before tick events also, so
160        /// that a serialize/unserialize is identical to an on-line
161        /// CPU switch.
162        Serialize_Pri		=   32,
163
164        /// CPU ticks must come after other associated CPU events
165        /// (such as writebacks).
166        CPU_Tick_Pri		=   50,
167
168        /// Statistics events (dump, reset, etc.) come after
169        /// everything else, but before exit.
170        Stat_Event_Pri		=   90,
171
172        /// Progress events come at the end.
173        Progress_Event_Pri      =   95,
174
175        /// If we want to exit on this cycle, it's the very last thing
176        /// we do.
177        Sim_Exit_Pri		=  100
178    };
179
180    /*
181     * Event constructor
182     * @param queue that the event gets scheduled on
183     */
184    Event(EventQueue *q, Priority p = Default_Pri)
185        : queue(q), next(NULL), _priority(p), _flags(None),
186#if TRACING_ON
187          when_created(curTick), when_scheduled(0),
188#endif
189          annotated_value(0)
190    {
191#ifndef NDEBUG
192        instanceId = ++instanceCounter;
193#endif
194    }
195
196    ~Event() {}
197
198    virtual const std::string name() const {
199#ifndef NDEBUG
200        return csprintf("Event_%d", instanceId);
201#else
202        return csprintf("Event_%x", (uintptr_t)this);
203#endif
204    }
205
206    /// Determine if the current event is scheduled
207    bool scheduled() const { return getFlags(Scheduled); }
208
209    /// Schedule the event with the current priority or default priority
210    void schedule(Tick t);
211
212    /// Reschedule the event with the current priority
213    // always parameter means to schedule if not already scheduled
214    void reschedule(Tick t, bool always = false);
215
216    /// Remove the event from the current schedule
217    void deschedule();
218
219    /// Return a C string describing the event.  This string should
220    /// *not* be dynamically allocated; just a const char array
221    /// describing the event class.
222    virtual const char *description() const;
223
224    /// Dump the current event data
225    void dump();
226
227    /*
228     * This member function is invoked when the event is processed
229     * (occurs).  There is no default implementation; each subclass
230     * must provide its own implementation.  The event is not
231     * automatically deleted after it is processed (to allow for
232     * statically allocated event objects).
233     *
234     * If the AutoDestroy flag is set, the object is deleted once it
235     * is processed.
236     */
237    virtual void process() = 0;
238
239    void annotate(unsigned value) { annotated_value = value; };
240    unsigned annotation() { return annotated_value; }
241
242    /// Squash the current event
243    void squash() { setFlags(Squashed); }
244
245    /// Check whether the event is squashed
246    bool squashed() { return getFlags(Squashed); }
247
248    /// See if this is a SimExitEvent (without resorting to RTTI)
249    bool isExitEvent() { return getFlags(IsExitEvent); }
250
251    /// Get the time that the event is scheduled
252    Tick when() const { return _when; }
253
254    /// Get the event priority
255    int priority() const { return _priority; }
256
257    struct priority_compare :
258    public std::binary_function<Event *, Event *, bool>
259    {
260        bool operator()(const Event *l, const Event *r) const {
261            return l->when() >= r->when() || l->priority() >= r->priority();
262        }
263    };
264
265    virtual void serialize(std::ostream &os);
266    virtual void unserialize(Checkpoint *cp, const std::string &section);
267};
268
269template <class T, void (T::* F)()>
270void
271DelayFunction(Tick when, T *object)
272{
273    class DelayEvent : public Event
274    {
275      private:
276        T *object;
277
278      public:
279        DelayEvent(Tick when, T *o)
280            : Event(&mainEventQueue), object(o)
281            { setFlags(this->AutoDestroy); schedule(when); }
282        void process() { (object->*F)(); }
283        const char *description() const { return "delay"; }
284    };
285
286    new DelayEvent(when, object);
287}
288
289template <class T, void (T::* F)()>
290class EventWrapper : public Event
291{
292  private:
293    T *object;
294
295  public:
296    EventWrapper(T *obj, bool del = false,
297                 EventQueue *q = &mainEventQueue,
298                 Priority p = Default_Pri)
299        : Event(q, p), object(obj)
300    {
301        if (del)
302            setFlags(AutoDelete);
303    }
304
305    EventWrapper(T *obj, Tick t, bool del = false,
306                 EventQueue *q = &mainEventQueue,
307                 Priority p = Default_Pri)
308        : Event(q, p), object(obj)
309    {
310        if (del)
311            setFlags(AutoDelete);
312        schedule(t);
313    }
314
315    void process() { (object->*F)(); }
316};
317
318/*
319 * Queue of events sorted in time order
320 */
321class EventQueue : public Serializable
322{
323  protected:
324    std::string objName;
325
326  private:
327    Event *head;
328
329    void insert(Event *event);
330    void remove(Event *event);
331
332  public:
333
334    // constructor
335    EventQueue(const std::string &n)
336        : objName(n), head(NULL)
337    {}
338
339    virtual const std::string name() const { return objName; }
340
341    // schedule the given event on this queue
342    void schedule(Event *ev);
343    void deschedule(Event *ev);
344    void reschedule(Event *ev);
345
346    Tick nextTick() { return head->when(); }
347    Event *serviceOne();
348
349    // process all events up to the given timestamp.  we inline a
350    // quick test to see if there are any events to process; if so,
351    // call the internal out-of-line version to process them all.
352    void serviceEvents(Tick when) {
353        while (!empty()) {
354            if (nextTick() > when)
355                break;
356
357            /**
358             * @todo this assert is a good bug catcher.  I need to
359             * make it true again.
360             */
361            //assert(head->when() >= when && "event scheduled in the past");
362            serviceOne();
363        }
364    }
365
366    // default: process all events up to 'now' (curTick)
367    void serviceEvents() { serviceEvents(curTick); }
368
369    // return true if no events are queued
370    bool empty() { return head == NULL; }
371
372    void dump();
373
374    Tick nextEventTime() { return empty() ? curTick : head->when(); }
375
376    virtual void serialize(std::ostream &os);
377    virtual void unserialize(Checkpoint *cp, const std::string &section);
378};
379
380
381//////////////////////
382//
383// inline functions
384//
385// can't put these inside declaration due to circular dependence
386// between Event and EventQueue classes.
387//
388//////////////////////
389
390// schedule at specified time (place on event queue specified via
391// constructor)
392inline void
393Event::schedule(Tick t)
394{
395    assert(!scheduled());
396//    if (t < curTick)
397//        warn("t is less than curTick, ensure you don't want cycles");
398
399    setFlags(Scheduled);
400#if TRACING_ON
401    when_scheduled = curTick;
402#endif
403    _when = t;
404    queue->schedule(this);
405}
406
407inline void
408Event::deschedule()
409{
410    assert(scheduled());
411
412    clearFlags(Squashed);
413    clearFlags(Scheduled);
414    queue->deschedule(this);
415}
416
417inline void
418Event::reschedule(Tick t, bool always)
419{
420    assert(scheduled() || always);
421
422#if TRACING_ON
423    when_scheduled = curTick;
424#endif
425    _when = t;
426
427    if (scheduled()) {
428        clearFlags(Squashed);
429        queue->reschedule(this);
430    } else {
431        setFlags(Scheduled);
432        queue->schedule(this);
433    }
434}
435
436inline void
437EventQueue::schedule(Event *event)
438{
439    insert(event);
440    if (DTRACE(Event))
441        event->trace("scheduled");
442}
443
444inline void
445EventQueue::deschedule(Event *event)
446{
447    remove(event);
448    if (DTRACE(Event))
449        event->trace("descheduled");
450}
451
452inline void
453EventQueue::reschedule(Event *event)
454{
455    remove(event);
456    insert(event);
457    if (DTRACE(Event))
458        event->trace("rescheduled");
459}
460
461
462
463#endif // __SIM_EVENTQ_HH__
464