ticked_object.hh revision 12113:bdf1545c9919 
1/*
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4 *
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23 * this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Authors: Andrew Bardsley
38 */
39
40/**
41 * @file
42 *
43 *  Base classes for ClockedObjects which have evaluate functions to
44 *  look like clock ticking operations.  TickedObject attaches gem5's event
45 *  queue to Ticked to apply actual scheduling.
46 */
47
48#ifndef __SIM_TICKED_OBJECT_HH__
49#define __SIM_TICKED_OBJECT_HH__
50
51#include "sim/clocked_object.hh"
52
53class TickedObjectParams;
54
55/** Ticked attaches gem5's event queue/scheduler to evaluate
56 *  calls and provides a start/stop interface to ticking.
57 *
58 *  Ticked is not a ClockedObject but can be attached to one by
59 *  inheritance and by calling regStats, serialize/unserialize */
60class Ticked : public Serializable
61{
62  protected:
63    /** An event to call process periodically */
64    class ClockEvent : public Event
65    {
66      public:
67        Ticked &owner;
68
69        ClockEvent(Ticked &owner_, Priority priority) :
70            Event(priority),
71            owner(owner_)
72        { }
73
74        /** Evaluate and reschedule */
75        void
76        process()
77        {
78            ++owner.tickCycles;
79            ++owner.numCycles;
80            owner.countCycles(Cycles(1));
81            owner.evaluate();
82            if (owner.running) {
83                owner.object.schedule(this,
84                    owner.object.clockEdge(Cycles(1)));
85            }
86        }
87    };
88
89    friend class ClockEvent;
90
91    /** ClockedObject who is responsible for this Ticked's actions/stats */
92    ClockedObject &object;
93
94    /** The single instance of ClockEvent used */
95    ClockEvent event;
96
97    /** Have I been started? and am not stopped */
98    bool running;
99
100    /** Time of last stop event to calculate run time */
101    Cycles lastStopped;
102
103  private:
104    /** Locally allocated stats */
105    Stats::Scalar *numCyclesLocal;
106
107  protected:
108    /** Total number of cycles either ticked or spend stopped */
109    Stats::Scalar &numCycles;
110
111    /** Number of cycles ticked */
112    Stats::Scalar tickCycles;
113
114    /** Number of cycles stopped */
115    Stats::Formula idleCycles;
116
117  public:
118    Ticked(ClockedObject &object_,
119        Stats::Scalar *imported_num_cycles = NULL,
120        Event::Priority priority = Event::CPU_Tick_Pri);
121
122    virtual ~Ticked() { }
123
124    /** Register {num,ticks}Cycles if necessary.  If numCycles is
125     *  imported, be sure to register it *before* calling this regStats */
126    void regStats();
127
128    /** Start ticking */
129    void
130    start()
131    {
132        if (!running) {
133            if (!event.scheduled())
134                object.schedule(event, object.clockEdge(Cycles(1)));
135            running = true;
136            numCycles += cyclesSinceLastStopped();
137            countCycles(cyclesSinceLastStopped());
138        }
139    }
140
141    /** How long have we been stopped for? */
142    Cycles
143    cyclesSinceLastStopped() const
144    {
145        return object.curCycle() - lastStopped;
146    }
147
148    /** Reset stopped time to current time */
149    void
150    resetLastStopped()
151    {
152        lastStopped = object.curCycle();
153    }
154
155    /** Cancel the next tick event and issue no more */
156    void
157    stop()
158    {
159        if (running) {
160            if (event.scheduled())
161                object.deschedule(event);
162            running = false;
163            resetLastStopped();
164        }
165    }
166
167    /** Checkpoint lastStopped */
168    void serialize(CheckpointOut &cp) const override;
169    void unserialize(CheckpointIn &cp) override;
170
171    /** Action to call on the clock tick */
172    virtual void evaluate() = 0;
173
174    /**
175     * Callback to handle cycle statistics and probes.
176     *
177     * This callback is called at the beginning of a new cycle active
178     * cycle and when restarting the ticked object. The delta
179     * parameter indicates the number of cycles elapsed since the
180     * previous call is normally '1' unless the object has been
181     * stopped and restarted.
182     *
183     * @param delta Number of cycles since the previous call.
184     */
185    virtual void countCycles(Cycles delta) {}
186};
187
188/** TickedObject attaches Ticked to ClockedObject and can be used as
189 *  a base class where ticked operation */
190class TickedObject : public ClockedObject, public Ticked
191{
192  public:
193    TickedObject(const TickedObjectParams *params,
194        Event::Priority priority = Event::CPU_Tick_Pri);
195
196    /** Disambiguate to make these functions overload correctly */
197    using ClockedObject::regStats;
198    using ClockedObject::serialize;
199    using ClockedObject::unserialize;
200
201    /** Pass on regStats, serialize etc. onto Ticked */
202    void regStats() override;
203    void serialize(CheckpointOut &cp) const override;
204    void unserialize(CheckpointIn &cp) override;
205};
206
207#endif /* __SIM_TICKED_OBJECT_HH__ */
208