clocked_object.hh revision 11527 
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 "base/misc.hh"
55#include "enums/PwrState.hh"
56#include "params/ClockedObject.hh"
57#include "sim/core.hh"
58#include "sim/clock_domain.hh"
59#include "sim/sim_object.hh"
60
61/**
62 * Helper class for objects that need to be clocked. Clocked objects
63 * typically inherit from this class. Objects that need SimObject
64 * functionality as well should inherit from ClockedObject.
65 */
66class Clocked
67{
68
69  private:
70    // the tick value of the next clock edge (>= curTick()) at the
71    // time of the last call to update()
72    mutable Tick tick;
73
74    // The cycle counter value corresponding to the current value of
75    // 'tick'
76    mutable Cycles cycle;
77
78    /**
79     *  Align cycle and tick to the next clock edge if not already done. When
80     *  complete, tick must be at least curTick().
81     */
82    void update() const
83    {
84        // both tick and cycle are up-to-date and we are done, note
85        // that the >= is important as it captures cases where tick
86        // has already passed curTick()
87        if (tick >= curTick())
88            return;
89
90        // optimise for the common case and see if the tick should be
91        // advanced by a single clock period
92        tick += clockPeriod();
93        ++cycle;
94
95        // see if we are done at this point
96        if (tick >= curTick())
97            return;
98
99        // if not, we have to recalculate the cycle and tick, we
100        // perform the calculations in terms of relative cycles to
101        // allow changes to the clock period in the future
102        Cycles elapsedCycles(divCeil(curTick() - tick, clockPeriod()));
103        cycle += elapsedCycles;
104        tick += elapsedCycles * clockPeriod();
105    }
106
107    /**
108     * The clock domain this clocked object belongs to
109     */
110    ClockDomain &clockDomain;
111
112  protected:
113
114    /**
115     * Create a clocked object and set the clock domain based on the
116     * parameters.
117     */
118    Clocked(ClockDomain &clk_domain)
119        : tick(0), cycle(0), clockDomain(clk_domain)
120    {
121        // Register with the clock domain, so that if the clock domain
122        // frequency changes, we can update this object's tick.
123        clockDomain.registerWithClockDomain(this);
124    }
125
126    Clocked(Clocked &) = delete;
127    Clocked &operator=(Clocked &) = delete;
128
129    /**
130     * Virtual destructor due to inheritance.
131     */
132    virtual ~Clocked() { }
133
134    /**
135     * Reset the object's clock using the current global tick value. Likely
136     * to be used only when the global clock is reset. Currently, this done
137     * only when Ruby is done warming up the memory system.
138     */
139    void resetClock() const
140    {
141        Cycles elapsedCycles(divCeil(curTick(), clockPeriod()));
142        cycle = elapsedCycles;
143        tick = elapsedCycles * clockPeriod();
144    }
145
146  public:
147
148    /**
149     * Update the tick to the current tick.
150     *
151     */
152    inline void updateClockPeriod() const
153    {
154        update();
155    }
156
157    /**
158     * Determine the tick when a cycle begins, by default the current one, but
159     * the argument also enables the caller to determine a future cycle. When
160     * curTick() is on a clock edge, the number of cycles in the parameter is
161     * added to curTick() to be returned. When curTick() is not aligned to a
162     * clock edge, the number of cycles in the parameter is added to the next
163     * clock edge.
164     *
165     * @param cycles The number of cycles into the future
166     *
167     * @return The start tick when the requested clock edge occurs. Precisely,
168     * this tick can be
169     *     curTick() + [0, clockPeriod()) + clockPeriod() * cycles
170     */
171    inline Tick clockEdge(Cycles cycles = Cycles(0)) const
172    {
173        // align tick to the next clock edge
174        update();
175
176        // figure out when this future cycle is
177        return tick + clockPeriod() * cycles;
178    }
179
180    /**
181     * Determine the current cycle, corresponding to a tick aligned to
182     * a clock edge.
183     *
184     * @return When curTick() is on a clock edge, return the Cycle corresponding
185     * to that clock edge. When curTick() is not on a clock edge, return the
186     * Cycle corresponding to the next clock edge.
187     */
188    inline Cycles curCycle() const
189    {
190        // align cycle to the next clock edge.
191        update();
192
193        return cycle;
194    }
195
196    /**
197     * Based on the clock of the object, determine the start tick of the first
198     * cycle that is at least one cycle in the future. When curTick() is at the
199     * current cycle edge, this returns the next clock edge. When calling this
200     * during the middle of a cycle, this returns 2 clock edges in the future.
201     *
202     * @return The start tick of the first cycle that is at least one cycle in
203     * the future. Precisely, the returned tick can be in the range
204     *     curTick() + [clockPeriod(), 2 * clockPeriod())
205     */
206    Tick nextCycle() const
207    { return clockEdge(Cycles(1)); }
208
209    inline uint64_t frequency() const
210    {
211        return SimClock::Frequency / clockPeriod();
212    }
213
214    inline Tick clockPeriod() const
215    {
216        return clockDomain.clockPeriod();
217    }
218
219    inline double voltage() const
220    {
221        return clockDomain.voltage();
222    }
223
224    inline Cycles ticksToCycles(Tick t) const
225    { return Cycles(divCeil(t, clockPeriod())); }
226
227    inline Tick cyclesToTicks(Cycles c) const
228    { return clockPeriod() * c; }
229};
230
231/**
232 * The ClockedObject class extends the SimObject with a clock and
233 * accessor functions to relate ticks to the cycles of the object.
234 */
235class ClockedObject
236    : public SimObject, public Clocked
237{
238  public:
239    ClockedObject(const ClockedObjectParams *p);
240
241    /** Parameters of ClockedObject */
242    typedef ClockedObjectParams Params;
243    const Params* params() const
244    { return reinterpret_cast<const Params*>(_params); }
245
246    void serialize(CheckpointOut &cp) const override;
247    void unserialize(CheckpointIn &cp) override;
248
249    inline Enums::PwrState pwrState() const
250    { return _currPwrState; }
251
252    inline std::string pwrStateName() const
253    { return Enums::PwrStateStrings[_currPwrState]; }
254
255    /** Returns the percentage residency for each power state */
256    std::vector<double> pwrStateWeights() const;
257
258    /**
259     * Record stats values like state residency by computing the time
260     * difference from previous update. Also, updates the previous evaluation
261     * tick once all stats are recorded.
262     * Usually called on power state change and stats dump callback.
263     */
264    void computeStats();
265
266    void pwrState(Enums::PwrState);
267    void regStats();
268
269  protected:
270
271    /** To keep track of the current power state */
272    Enums::PwrState _currPwrState;
273
274    Tick prvEvalTick;
275
276    Stats::Scalar numPwrStateTransitions;
277    Stats::Distribution pwrStateClkGateDist;
278    Stats::Vector pwrStateResidencyTicks;
279
280};
281
282class ClockedObjectDumpCallback : public Callback
283{
284    ClockedObject *co;
285  public:
286    ClockedObjectDumpCallback(ClockedObject *co_t) : co(co_t) {}
287    virtual void process() { co->computeStats(); };
288};
289
290#endif //__SIM_CLOCKED_OBJECT_HH__
291