clocked_object.hh revision 11800:54436a1784dc 
1/*
2 * Copyright (c) 2012-2013, 2015-2016 ARM Limited
3 * Copyright (c) 2013 Cornell University
4 * All rights reserved
5 *
6 * The license below extends only to copyright in the software and shall
7 * not be construed as granting a license to any other intellectual
8 * property including but not limited to intellectual property relating
9 * to a hardware implementation of the functionality of the software
10 * licensed hereunder.  You may use the software subject to the license
11 * terms below provided that you ensure that this notice is replicated
12 * unmodified and in its entirety in all distributions of the software,
13 * modified or unmodified, in source code or in binary form.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions are
17 * met: redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer;
19 * redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution;
22 * neither the name of the copyright holders nor the names of its
23 * contributors may be used to endorse or promote products derived from
24 * this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
27 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
28 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
29 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
30 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
31 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
32 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
36 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 * Authors: Andreas Hansson
39 *          Christopher Torng
40 *          Akash Bagdia
41 *          David Guillen Fandos
42 */
43
44/**
45 * @file
46 * ClockedObject declaration and implementation.
47 */
48
49#ifndef __SIM_CLOCKED_OBJECT_HH__
50#define __SIM_CLOCKED_OBJECT_HH__
51
52#include "base/callback.hh"
53#include "base/intmath.hh"
54#include "enums/PwrState.hh"
55#include "params/ClockedObject.hh"
56#include "sim/core.hh"
57#include "sim/clock_domain.hh"
58#include "sim/sim_object.hh"
59
60/**
61 * Helper class for objects that need to be clocked. Clocked objects
62 * typically inherit from this class. Objects that need SimObject
63 * functionality as well should inherit from ClockedObject.
64 */
65class Clocked
66{
67
68  private:
69    // the tick value of the next clock edge (>= curTick()) at the
70    // time of the last call to update()
71    mutable Tick tick;
72
73    // The cycle counter value corresponding to the current value of
74    // 'tick'
75    mutable Cycles cycle;
76
77    /**
78     *  Align cycle and tick to the next clock edge if not already done. When
79     *  complete, tick must be at least curTick().
80     */
81    void update() const
82    {
83        // both tick and cycle are up-to-date and we are done, note
84        // that the >= is important as it captures cases where tick
85        // has already passed curTick()
86        if (tick >= curTick())
87            return;
88
89        // optimise for the common case and see if the tick should be
90        // advanced by a single clock period
91        tick += clockPeriod();
92        ++cycle;
93
94        // see if we are done at this point
95        if (tick >= curTick())
96            return;
97
98        // if not, we have to recalculate the cycle and tick, we
99        // perform the calculations in terms of relative cycles to
100        // allow changes to the clock period in the future
101        Cycles elapsedCycles(divCeil(curTick() - tick, clockPeriod()));
102        cycle += elapsedCycles;
103        tick += elapsedCycles * clockPeriod();
104    }
105
106    /**
107     * The clock domain this clocked object belongs to
108     */
109    ClockDomain &clockDomain;
110
111  protected:
112
113    /**
114     * Create a clocked object and set the clock domain based on the
115     * parameters.
116     */
117    Clocked(ClockDomain &clk_domain)
118        : tick(0), cycle(0), clockDomain(clk_domain)
119    {
120        // Register with the clock domain, so that if the clock domain
121        // frequency changes, we can update this object's tick.
122        clockDomain.registerWithClockDomain(this);
123    }
124
125    Clocked(Clocked &) = delete;
126    Clocked &operator=(Clocked &) = delete;
127
128    /**
129     * Virtual destructor due to inheritance.
130     */
131    virtual ~Clocked() { }
132
133    /**
134     * Reset the object's clock using the current global tick value. Likely
135     * to be used only when the global clock is reset. Currently, this done
136     * only when Ruby is done warming up the memory system.
137     */
138    void resetClock() const
139    {
140        Cycles elapsedCycles(divCeil(curTick(), clockPeriod()));
141        cycle = elapsedCycles;
142        tick = elapsedCycles * clockPeriod();
143    }
144
145  public:
146
147    /**
148     * Update the tick to the current tick.
149     *
150     */
151    inline void updateClockPeriod() const
152    {
153        update();
154    }
155
156    /**
157     * Determine the tick when a cycle begins, by default the current one, but
158     * the argument also enables the caller to determine a future cycle. When
159     * curTick() is on a clock edge, the number of cycles in the parameter is
160     * added to curTick() to be returned. When curTick() is not aligned to a
161     * clock edge, the number of cycles in the parameter is added to the next
162     * clock edge.
163     *
164     * @param cycles The number of cycles into the future
165     *
166     * @return The start tick when the requested clock edge occurs. Precisely,
167     * this tick can be
168     *     curTick() + [0, clockPeriod()) + clockPeriod() * cycles
169     */
170    inline Tick clockEdge(Cycles cycles = Cycles(0)) const
171    {
172        // align tick to the next clock edge
173        update();
174
175        // figure out when this future cycle is
176        return tick + clockPeriod() * cycles;
177    }
178
179    /**
180     * Determine the current cycle, corresponding to a tick aligned to
181     * a clock edge.
182     *
183     * @return When curTick() is on a clock edge, return the Cycle corresponding
184     * to that clock edge. When curTick() is not on a clock edge, return the
185     * Cycle corresponding to the next clock edge.
186     */
187    inline Cycles curCycle() const
188    {
189        // align cycle to the next clock edge.
190        update();
191
192        return cycle;
193    }
194
195    /**
196     * Based on the clock of the object, determine the start tick of the first
197     * cycle that is at least one cycle in the future. When curTick() is at the
198     * current cycle edge, this returns the next clock edge. When calling this
199     * during the middle of a cycle, this returns 2 clock edges in the future.
200     *
201     * @return The start tick of the first cycle that is at least one cycle in
202     * the future. Precisely, the returned tick can be in the range
203     *     curTick() + [clockPeriod(), 2 * clockPeriod())
204     */
205    Tick nextCycle() const
206    { return clockEdge(Cycles(1)); }
207
208    inline uint64_t frequency() const
209    {
210        return SimClock::Frequency / clockPeriod();
211    }
212
213    inline Tick clockPeriod() const
214    {
215        return clockDomain.clockPeriod();
216    }
217
218    inline double voltage() const
219    {
220        return clockDomain.voltage();
221    }
222
223    inline Cycles ticksToCycles(Tick t) const
224    { return Cycles(divCeil(t, clockPeriod())); }
225
226    inline Tick cyclesToTicks(Cycles c) const
227    { return clockPeriod() * c; }
228};
229
230/**
231 * The ClockedObject class extends the SimObject with a clock and
232 * accessor functions to relate ticks to the cycles of the object.
233 */
234class ClockedObject
235    : public SimObject, public Clocked
236{
237  public:
238    ClockedObject(const ClockedObjectParams *p);
239
240    /** Parameters of ClockedObject */
241    typedef ClockedObjectParams Params;
242    const Params* params() const
243    { return reinterpret_cast<const Params*>(_params); }
244
245    void serialize(CheckpointOut &cp) const override;
246    void unserialize(CheckpointIn &cp) override;
247
248    inline Enums::PwrState pwrState() const
249    { return _currPwrState; }
250
251    inline std::string pwrStateName() const
252    { return Enums::PwrStateStrings[_currPwrState]; }
253
254    /** Returns the percentage residency for each power state */
255    std::vector<double> pwrStateWeights() const;
256
257    /**
258     * Record stats values like state residency by computing the time
259     * difference from previous update. Also, updates the previous evaluation
260     * tick once all stats are recorded.
261     * Usually called on power state change and stats dump callback.
262     */
263    void computeStats();
264
265    void pwrState(Enums::PwrState);
266    void regStats() override;
267
268  protected:
269
270    /** To keep track of the current power state */
271    Enums::PwrState _currPwrState;
272
273    Tick prvEvalTick;
274
275    Stats::Scalar numPwrStateTransitions;
276    Stats::Distribution pwrStateClkGateDist;
277    Stats::Vector pwrStateResidencyTicks;
278
279};
280
281class ClockedObjectDumpCallback : public Callback
282{
283    ClockedObject *co;
284  public:
285    ClockedObjectDumpCallback(ClockedObject *co_t) : co(co_t) {}
286    virtual void process() { co->computeStats(); };
287};
288
289#endif //__SIM_CLOCKED_OBJECT_HH__
290