xref: /gem5/src/cpu/testers/traffic_gen/base.hh

/*
 * Copyright (c) 2012-2013, 2016-2018 ARM Limited
 * All rights reserved
 *
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 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
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 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Thomas Grass
 *          Andreas Hansson
 *          Sascha Bischoff
 */

#ifndef __CPU_TRAFFIC_GEN_BASE_HH__
#define __CPU_TRAFFIC_GEN_BASE_HH__

#include <memory>
#include <tuple>

#include "base/statistics.hh"
#include "mem/mem_object.hh"
#include "mem/qport.hh"

class BaseGen;
class System;
struct BaseTrafficGenParams;

/**
 * The traffic generator is a master module that generates stimuli for
 * the memory system, based on a collection of simple generator
 * behaviours that are either probabilistic or based on traces. It can
 * be used stand alone for creating test cases for interconnect and
 * memory controllers, or function as a black box replacement for
 * system components that are not yet modelled in detail, e.g. a video
 * engine or baseband subsystem.
 */
class BaseTrafficGen : public MemObject
{
  protected: // Params
    /**
     * The system used to determine which mode we are currently operating
     * in.
     */
    System *const system;

    /**
     * Determine whether to add elasticity in the request injection,
     * thus responding to backpressure by slowing things down.
     */
    const bool elasticReq;

    /**
     * Time to tolerate waiting for retries (not making progress),
     * until we declare things broken.
     */
    const Tick progressCheck;

  private:
    /**
     * Receive a retry from the neighbouring port and attempt to
     * resend the waiting packet.
     */
    void recvReqRetry();

    /** Transition to the next generator */
    void transition();

    /**
     * Schedule the update event based on nextPacketTick and
     * nextTransitionTick.
     */
    void scheduleUpdate();

    /**
     * Method to inform the user we have made no progress.
     */
    void noProgress();

    /**
     * Event to keep track of our progress, or lack thereof.
     */
    EventFunctionWrapper noProgressEvent;

    /** Time of next transition */
    Tick nextTransitionTick;

    /** Time of the next packet. */
    Tick nextPacketTick;


    /** Master port specialisation for the traffic generator */
    class TrafficGenPort : public MasterPort
    {
      public:

        TrafficGenPort(const std::string& name, BaseTrafficGen& traffic_gen)
            : MasterPort(name, &traffic_gen), trafficGen(traffic_gen)
        { }

      protected:

        void recvReqRetry() { trafficGen.recvReqRetry(); }

        bool recvTimingResp(PacketPtr pkt);

        void recvTimingSnoopReq(PacketPtr pkt) { }

        void recvFunctionalSnoop(PacketPtr pkt) { }

        Tick recvAtomicSnoop(PacketPtr pkt) { return 0; }

      private:

        BaseTrafficGen& trafficGen;

    };

    /**
     * Schedules event for next update and generates a new packet or
     * requests a new generatoir depending on the current time.
     */
    void update();

    /** The instance of master port used by the traffic generator. */
    TrafficGenPort port;

    /** Packet waiting to be sent. */
    PacketPtr retryPkt;

    /** Tick when the stalled packet was meant to be sent. */
    Tick retryPktTick;

    /** Event for scheduling updates */
    EventFunctionWrapper updateEvent;

    uint64_t numSuppressed;

  private: // Stats
    /** Count the number of generated packets. */
    Stats::Scalar numPackets;

    /** Count the number of retries. */
    Stats::Scalar numRetries;

    /** Count the time incurred from back-pressure. */
    Stats::Scalar retryTicks;

  public:
    BaseTrafficGen(const BaseTrafficGenParams* p);

    ~BaseTrafficGen() {}

    BaseMasterPort& getMasterPort(const std::string &if_name,
                                  PortID idx = InvalidPortID) override;

    void init() override;

    DrainState drain() override;

    void serialize(CheckpointOut &cp) const override;
    void unserialize(CheckpointIn &cp) override;

    /** Register statistics */
    void regStats() override;

  protected:
    void start();

    virtual std::shared_ptr<BaseGen> nextGenerator() = 0;

    /**
     * MasterID used in generated requests.
     */
    const MasterID masterID;

    /** Currently active generator */
    std::shared_ptr<BaseGen> activeGenerator;
};

#endif //__CPU_TRAFFIC_GEN_BASE_HH__