src/sim/clocked_object.hh

   1 /*
   2  * Copyright (c) 2012-2013, 2015 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  */
  66 class 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  */
 235 class 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
 261      * evaluation 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
 282 class 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__