ticked_object.hh revision 11169:44b5c183c3cd 
1/*
2 * Copyright (c) 2013-2014 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions are
16 * met: redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer;
18 * redistributions in binary form must reproduce the above copyright
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20 * documentation and/or other materials provided with the distribution;
21 * neither the name of the copyright holders nor the names of its
22 * contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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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 "params/TickedObject.hh"
52#include "sim/clocked_object.hh"
53
54/** Ticked attaches gem5's event queue/scheduler to evaluate
55 *  calls and provides a start/stop interface to ticking.
56 *
57 *  Ticked is not a ClockedObject but can be attached to one by
58 *  inheritance and by calling regStats, serialize/unserialize */
59class Ticked : public Serializable
60{
61  protected:
62    /** An event to call process periodically */
63    class ClockEvent : public Event
64    {
65      public:
66        Ticked &owner;
67
68        ClockEvent(Ticked &owner_, Priority priority) :
69            Event(priority),
70            owner(owner_)
71        { }
72
73        /** Evaluate and reschedule */
74        void
75        process()
76        {
77            ++owner.tickCycles;
78            ++owner.numCycles;
79            owner.countCycles(Cycles(1));
80            owner.evaluate();
81            if (owner.running) {
82                owner.object.schedule(this,
83                    owner.object.clockEdge(Cycles(1)));
84            }
85        }
86    };
87
88    friend class ClockEvent;
89
90    /** ClockedObject who is responsible for this Ticked's actions/stats */
91    ClockedObject &object;
92
93    /** The single instance of ClockEvent used */
94    ClockEvent event;
95
96    /** Have I been started? and am not stopped */
97    bool running;
98
99    /** Time of last stop event to calculate run time */
100    Cycles lastStopped;
101
102  private:
103    /** Locally allocated stats */
104    Stats::Scalar *numCyclesLocal;
105
106  protected:
107    /** Total number of cycles either ticked or spend stopped */
108    Stats::Scalar &numCycles;
109
110    /** Number of cycles ticked */
111    Stats::Scalar tickCycles;
112
113    /** Number of cycles stopped */
114    Stats::Formula idleCycles;
115
116  public:
117    Ticked(ClockedObject &object_,
118        Stats::Scalar *imported_num_cycles = NULL,
119        Event::Priority priority = Event::CPU_Tick_Pri);
120
121    virtual ~Ticked() { }
122
123    /** Register {num,ticks}Cycles if necessary.  If numCycles is
124     *  imported, be sure to register it *before* calling this regStats */
125    void regStats();
126
127    /** Start ticking */
128    void
129    start()
130    {
131        if (!running) {
132            if (!event.scheduled())
133                object.schedule(event, object.clockEdge(Cycles(1)));
134            running = true;
135            numCycles += cyclesSinceLastStopped();
136            countCycles(cyclesSinceLastStopped());
137        }
138    }
139
140    /** How long have we been stopped for? */
141    Cycles
142    cyclesSinceLastStopped() const
143    {
144        return object.curCycle() - lastStopped;
145    }
146
147    /** Reset stopped time to current time */
148    void
149    resetLastStopped()
150    {
151        lastStopped = object.curCycle();
152    }
153
154    /** Cancel the next tick event and issue no more */
155    void
156    stop()
157    {
158        if (running) {
159            if (event.scheduled())
160                object.deschedule(event);
161            running = false;
162            resetLastStopped();
163        }
164    }
165
166    /** Checkpoint lastStopped */
167    void serialize(CheckpointOut &cp) const override;
168    void unserialize(CheckpointIn &cp) override;
169
170    /** Action to call on the clock tick */
171    virtual void evaluate() = 0;
172
173    /**
174     * Callback to handle cycle statistics and probes.
175     *
176     * This callback is called at the beginning of a new cycle active
177     * cycle and when restarting the ticked object. The delta
178     * parameter indicates the number of cycles elapsed since the
179     * previous call is normally '1' unless the object has been
180     * stopped and restarted.
181     *
182     * @param delta Number of cycles since the previous call.
183     */
184    virtual void countCycles(Cycles delta) {}
185};
186
187/** TickedObject attaches Ticked to ClockedObject and can be used as
188 *  a base class where ticked operation */
189class TickedObject : public ClockedObject, public Ticked
190{
191  public:
192    TickedObject(TickedObjectParams *params,
193        Event::Priority priority = Event::CPU_Tick_Pri);
194
195    /** Disambiguate to make these functions overload correctly */
196    using ClockedObject::regStats;
197    using ClockedObject::serialize;
198    using ClockedObject::unserialize;
199
200    /** Pass on regStats, serialize etc. onto Ticked */
201    void regStats() override;
202    void serialize(CheckpointOut &cp) const override;
203    void unserialize(CheckpointIn &cp) override;
204};
205
206#endif /* __SIM_TICKED_OBJECT_HH__ */
207