src/sim/ticked_object.hh

   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
  19  * notice, this list of conditions and the following disclaimer in the
  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
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  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 */
  59 class 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 */
 189 class 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__ */