gem5/src/mem/cache/base_cache.hh

/*
 * Copyright (c) 2003-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * 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
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * 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,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Erik Hallnor
 *          Steve Reinhardt
 *          Ron Dreslinski
 */

/**
 * @file
 * Declares a basic cache interface BaseCache.
 */

#ifndef __BASE_CACHE_HH__
#define __BASE_CACHE_HH__

#include <vector>
#include <string>
#include <list>
#include <inttypes.h>

#include "base/misc.hh"
#include "base/statistics.hh"
#include "base/trace.hh"
#include "mem/mem_object.hh"
#include "mem/packet.hh"
#include "mem/port.hh"
#include "mem/request.hh"
#include "sim/eventq.hh"

/**
 * Reasons for Caches to be Blocked.
 */
enum BlockedCause{
    Blocked_NoMSHRs,
    Blocked_NoTargets,
    Blocked_NoWBBuffers,
    Blocked_Coherence,
    NUM_BLOCKED_CAUSES
};

/**
 * Reasons for cache to request a bus.
 */
enum RequestCause{
    Request_MSHR,
    Request_WB,
    Request_Coherence,
    Request_PF
};

class MSHR;
/**
 * A basic cache interface. Implements some common functions for speed.
 */
class BaseCache : public MemObject
{
    class CachePort : public Port
    {
      public:
        BaseCache *cache;

      protected:
        Event *responseEvent;

        CachePort(const std::string &_name, BaseCache *_cache);

        virtual void recvStatusChange(Status status);

        virtual void getDeviceAddressRanges(AddrRangeList &resp,
                                            bool &snoop);

        virtual int deviceBlockSize();

        bool recvRetryCommon();

      public:
        void setOtherPort(CachePort *_otherPort) { otherPort = _otherPort; }

        void setBlocked();

        void clearBlocked();

        bool checkFunctional(PacketPtr pkt);

        void checkAndSendFunctional(PacketPtr pkt);

        bool canDrain() { return drainList.empty() && transmitList.empty(); }

        bool drainResponse();

        CachePort *otherPort;

        bool blocked;

        bool mustSendRetry;

        bool waitingOnRetry;

        /**
         * Bit vector for the outstanding requests for the master interface.
         */
        uint8_t requestCauses;

        std::list<PacketPtr> drainList;

        std::list<std::pair<Tick,PacketPtr> > transmitList;

        bool isBusRequested() { return requestCauses != 0; }

        // These need to be virtual since the Event objects depend on
        // cache template parameters.
        virtual void scheduleRequestEvent(Tick t) = 0;

        void requestBus(RequestCause cause, Tick time)
        {
            if (!isBusRequested() && !waitingOnRetry) {
                scheduleRequestEvent(time);
            }
            requestCauses |= (1 << cause);
        }

        void deassertBusRequest(RequestCause cause)
        {
            requestCauses &= ~(1 << cause);
        }

        void respond(PacketPtr pkt, Tick time);
    };

  public: //Made public so coherence can get at it.
    CachePort *cpuSidePort;
    CachePort *memSidePort;

  private:
    /**
     * Bit vector of the blocking reasons for the access path.
     * @sa #BlockedCause
     */
    uint8_t blocked;

    /**
     * Bit vector for the blocking reasons for the snoop path.
     * @sa #BlockedCause
     */
    uint8_t blockedSnoop;

  protected:

    /** Stores time the cache blocked for statistics. */
    Tick blockedCycle;

    /** Block size of this cache */
    const int blkSize;

    /** The number of misses to trigger an exit event. */
    Counter missCount;

    /** The drain event. */
    Event *drainEvent;

  public:
    // Statistics
    /**
     * @addtogroup CacheStatistics
     * @{
     */

    /** Number of hits per thread for each type of command. @sa Packet::Command */
    Stats::Vector<> hits[MemCmd::NUM_MEM_CMDS];
    /** Number of hits for demand accesses. */
    Stats::Formula demandHits;
    /** Number of hit for all accesses. */
    Stats::Formula overallHits;

    /** Number of misses per thread for each type of command. @sa Packet::Command */
    Stats::Vector<> misses[MemCmd::NUM_MEM_CMDS];
    /** Number of misses for demand accesses. */
    Stats::Formula demandMisses;
    /** Number of misses for all accesses. */
    Stats::Formula overallMisses;

    /**
     * Total number of cycles per thread/command spent waiting for a miss.
     * Used to calculate the average miss latency.
     */
    Stats::Vector<> missLatency[MemCmd::NUM_MEM_CMDS];
    /** Total number of cycles spent waiting for demand misses. */
    Stats::Formula demandMissLatency;
    /** Total number of cycles spent waiting for all misses. */
    Stats::Formula overallMissLatency;

    /** The number of accesses per command and thread. */
    Stats::Formula accesses[MemCmd::NUM_MEM_CMDS];
    /** The number of demand accesses. */
    Stats::Formula demandAccesses;
    /** The number of overall accesses. */
    Stats::Formula overallAccesses;

    /** The miss rate per command and thread. */
    Stats::Formula missRate[MemCmd::NUM_MEM_CMDS];
    /** The miss rate of all demand accesses. */
    Stats::Formula demandMissRate;
    /** The miss rate for all accesses. */
    Stats::Formula overallMissRate;

    /** The average miss latency per command and thread. */
    Stats::Formula avgMissLatency[MemCmd::NUM_MEM_CMDS];
    /** The average miss latency for demand misses. */
    Stats::Formula demandAvgMissLatency;
    /** The average miss latency for all misses. */
    Stats::Formula overallAvgMissLatency;

    /** The total number of cycles blocked for each blocked cause. */
    Stats::Vector<> blocked_cycles;
    /** The number of times this cache blocked for each blocked cause. */
    Stats::Vector<> blocked_causes;

    /** The average number of cycles blocked for each blocked cause. */
    Stats::Formula avg_blocked;

    /** The number of fast writes (WH64) performed. */
    Stats::Scalar<> fastWrites;

    /** The number of cache copies performed. */
    Stats::Scalar<> cacheCopies;

    /**
     * @}
     */

    /**
     * Register stats for this object.
     */
    virtual void regStats();

  public:

    class Params
    {
      public:
        /** List of address ranges of this cache. */
        std::vector<Range<Addr> > addrRange;
        /** The hit latency for this cache. */
        int hitLatency;
        /** The block size of this cache. */
        int blkSize;
        /**
         * The maximum number of misses this cache should handle before
         * ending the simulation.
         */
        Counter maxMisses;

        /**
         * Construct an instance of this parameter class.
         */
        Params(std::vector<Range<Addr> > addr_range,
               int hit_latency, int _blkSize, Counter max_misses)
            : addrRange(addr_range), hitLatency(hit_latency), blkSize(_blkSize),
              maxMisses(max_misses)
        {
        }
    };

    /**
     * Create and initialize a basic cache object.
     * @param name The name of this cache.
     * @param hier_params Pointer to the HierParams object for this hierarchy
     * of this cache.
     * @param params The parameter object for this BaseCache.
     */
    BaseCache(const std::string &name, Params &params);

    ~BaseCache()
    {
    }

    virtual void init();

    /**
     * Query block size of a cache.
     * @return  The block size
     */
    int getBlockSize() const
    {
        return blkSize;
    }

    /**
     * Returns true if the cache is blocked for accesses.
     */
    bool isBlocked()
    {
        return blocked != 0;
    }

    /**
     * Returns true if the cache is blocked for snoops.
     */
    bool isBlockedForSnoop()
    {
        return blockedSnoop != 0;
    }

    /**
     * Marks the access path of the cache as blocked for the given cause. This
     * also sets the blocked flag in the slave interface.
     * @param cause The reason for the cache blocking.
     */
    void setBlocked(BlockedCause cause)
    {
        uint8_t flag = 1 << cause;
        if (blocked == 0) {
            blocked_causes[cause]++;
            blockedCycle = curTick;
        }
        int old_state = blocked;
        if (!(blocked & flag)) {
            //Wasn't already blocked for this cause
            blocked |= flag;
            DPRINTF(Cache,"Blocking for cause %s\n", cause);
            if (!old_state)
                cpuSidePort->setBlocked();
        }
    }

    /**
     * Marks the snoop path of the cache as blocked for the given cause. This
     * also sets the blocked flag in the master interface.
     * @param cause The reason to block the snoop path.
     */
    void setBlockedForSnoop(BlockedCause cause)
    {
        uint8_t flag = 1 << cause;
        uint8_t old_state = blockedSnoop;
        if (!(blockedSnoop & flag)) {
            //Wasn't already blocked for this cause
            blockedSnoop |= flag;
            if (!old_state)
                memSidePort->setBlocked();
        }
    }

    /**
     * Marks the cache as unblocked for the given cause. This also clears the
     * blocked flags in the appropriate interfaces.
     * @param cause The newly unblocked cause.
     * @warning Calling this function can cause a blocked request on the bus to
     * access the cache. The cache must be in a state to handle that request.
     */
    void clearBlocked(BlockedCause cause)
    {
        uint8_t flag = 1 << cause;
        DPRINTF(Cache,"Unblocking for cause %s, causes left=%i\n",
                cause, blocked);
        if (blocked & flag)
        {
            blocked &= ~flag;
            if (!isBlocked()) {
                blocked_cycles[cause] += curTick - blockedCycle;
                DPRINTF(Cache,"Unblocking from all causes\n");
                cpuSidePort->clearBlocked();
            }
        }
        if (blockedSnoop & flag)
        {
            blockedSnoop &= ~flag;
            if (!isBlockedForSnoop()) {
                memSidePort->clearBlocked();
            }
        }
    }

    /**
     * True if the memory-side bus should be requested.
     * @return True if there are outstanding requests for the master bus.
     */
    bool isMemSideBusRequested()
    {
        return memSidePort->isBusRequested();
    }

    /**
     * Request the master bus for the given cause and time.
     * @param cause The reason for the request.
     * @param time The time to make the request.
     */
    void requestMemSideBus(RequestCause cause, Tick time)
    {
        memSidePort->requestBus(cause, time);
    }

    /**
     * Clear the master bus request for the given cause.
     * @param cause The request reason to clear.
     */
    void deassertMemSideBusRequest(RequestCause cause)
    {
        memSidePort->deassertBusRequest(cause);
        checkDrain();
    }

    /**
     * Send a response to the slave interface.
     * @param pkt The request being responded to.
     * @param time The time the response is ready.
     */
    void respond(PacketPtr pkt, Tick time)
    {
        cpuSidePort->respond(pkt, time);
    }

    /**
     * Suppliess the data if cache to cache transfers are enabled.
     * @param pkt The bus transaction to fulfill.
     */
    void respondToSnoop(PacketPtr pkt, Tick time)
    {
        memSidePort->respond(pkt, time);
    }

    virtual unsigned int drain(Event *de);

    void checkDrain()
    {
        if (drainEvent && canDrain()) {
            drainEvent->process();
            changeState(SimObject::Drained);
            // Clear the drain event
            drainEvent = NULL;
        }
    }

    bool canDrain()
    {
        if (isMemSideBusRequested()) {
            return false;
        } else if (memSidePort && !memSidePort->canDrain()) {
            return false;
        } else if (cpuSidePort && !cpuSidePort->canDrain()) {
            return false;
        }
        return true;
    }

    virtual bool inCache(Addr addr) = 0;

    virtual bool inMissQueue(Addr addr) = 0;
};

#endif //__BASE_CACHE_HH__