coherent_xbar.hh

Go to the documentation of this file.

/*
 * Copyright (c) 2011-2015, 2017, 2019 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * 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
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2002-2005 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: Ron Dreslinski
 *          Ali Saidi
 *          Andreas Hansson
 *          William Wang
 */

#ifndef __MEM_COHERENT_XBAR_HH__
#define __MEM_COHERENT_XBAR_HH__

#include <unordered_map>
#include <unordered_set>

#include "mem/snoop_filter.hh"
#include "mem/xbar.hh"
#include "params/CoherentXBar.hh"

class CoherentXBar : public BaseXBar
{

  protected:

    std::vector<ReqLayer*> reqLayers;
    std::vector<RespLayer*> respLayers;
    std::vector<SnoopRespLayer*> snoopLayers;

    class CoherentXBarSlavePort : public QueuedSlavePort
    {

      private:

        CoherentXBar &xbar;

        RespPacketQueue queue;

      public:

        CoherentXBarSlavePort(const std::string &_name,
                             CoherentXBar &_xbar, PortID _id)
            : QueuedSlavePort(_name, &_xbar, queue, _id), xbar(_xbar),
              queue(_xbar, *this)
        { }

      protected:

        bool
        recvTimingReq(PacketPtr pkt) override
        {
            return xbar.recvTimingReq(pkt, id);
        }

        bool
        recvTimingSnoopResp(PacketPtr pkt) override
        {
            return xbar.recvTimingSnoopResp(pkt, id);
        }

        Tick
        recvAtomic(PacketPtr pkt) override
        {
            return xbar.recvAtomicBackdoor(pkt, id);
        }

        Tick
        recvAtomicBackdoor(PacketPtr pkt, MemBackdoorPtr &backdoor) override
        {
            return xbar.recvAtomicBackdoor(pkt, id, &backdoor);
        }

        void
        recvFunctional(PacketPtr pkt) override
        {
            xbar.recvFunctional(pkt, id);
        }

        AddrRangeList
        getAddrRanges() const override
        {
            return xbar.getAddrRanges();
        }

    };

    class CoherentXBarMasterPort : public MasterPort
    {
      private:
        CoherentXBar &xbar;

      public:

        CoherentXBarMasterPort(const std::string &_name,
                              CoherentXBar &_xbar, PortID _id)
            : MasterPort(_name, &_xbar, _id), xbar(_xbar)
        { }

      protected:

        bool isSnooping() const override { return true; }

        bool
        recvTimingResp(PacketPtr pkt) override
        {
            return xbar.recvTimingResp(pkt, id);
        }

        void
        recvTimingSnoopReq(PacketPtr pkt) override
        {
            return xbar.recvTimingSnoopReq(pkt, id);
        }

        Tick
        recvAtomicSnoop(PacketPtr pkt) override
        {
            return xbar.recvAtomicSnoop(pkt, id);
        }

        void
        recvFunctionalSnoop(PacketPtr pkt) override
        {
            xbar.recvFunctionalSnoop(pkt, id);
        }

        void recvRangeChange() override { xbar.recvRangeChange(id); }
        void recvReqRetry() override { xbar.recvReqRetry(id); }

    };

    class SnoopRespPort : public MasterPort
    {

      private:

        QueuedSlavePort& slavePort;

      public:

        SnoopRespPort(QueuedSlavePort& slave_port, CoherentXBar& _xbar) :
            MasterPort(slave_port.name() + ".snoopRespPort", &_xbar),
            slavePort(slave_port) { }

        void
        sendRetryResp() override
        {
            // forward it as a snoop response retry
            slavePort.sendRetrySnoopResp();
        }

        void
        recvReqRetry() override
        {
            panic("SnoopRespPort should never see retry");
        }

        bool
        recvTimingResp(PacketPtr pkt) override
        {
            panic("SnoopRespPort should never see timing response");
        }

    };

    std::vector<SnoopRespPort*> snoopRespPorts;

    std::vector<QueuedSlavePort*> snoopPorts;

    std::unordered_set<RequestPtr> outstandingSnoop;

    std::unordered_map<PacketId, PacketPtr> outstandingCMO;

    System *system;

    SnoopFilter *snoopFilter;

    const Cycles snoopResponseLatency;

    const unsigned int maxOutstandingSnoopCheck;

    const unsigned int maxRoutingTableSizeCheck;

    const bool pointOfCoherency;

    const bool pointOfUnification;

    std::unique_ptr<Packet> pendingDelete;

    bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);
    bool recvTimingResp(PacketPtr pkt, PortID master_port_id);
    void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);
    bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);
    void recvReqRetry(PortID master_port_id);

    void
    forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id)
    {
        forwardTiming(pkt, exclude_slave_port_id, snoopPorts);
    }

    void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id,
                       const std::vector<QueuedSlavePort*>& dests);

    Tick recvAtomicBackdoor(PacketPtr pkt, PortID slave_port_id,
                            MemBackdoorPtr *backdoor=nullptr);
    Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);

    std::pair<MemCmd, Tick>
    forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id)
    {
        return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID,
                             snoopPorts);
    }

    std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
                                          PortID exclude_slave_port_id,
                                          PortID source_master_port_id,
                                          const std::vector<QueuedSlavePort*>&
                                          dests);

    void recvFunctional(PacketPtr pkt, PortID slave_port_id);

    void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);

    void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);

    bool sinkPacket(const PacketPtr pkt) const;

    bool forwardPacket(const PacketPtr pkt);

    bool
    isDestination(const PacketPtr pkt) const
    {
        return (pkt->req->isToPOC() && pointOfCoherency) ||
            (pkt->req->isToPOU() && pointOfUnification);
    }

    Stats::Scalar snoops;
    Stats::Scalar snoopTraffic;
    Stats::Distribution snoopFanout;

  public:

    virtual void init();

    CoherentXBar(const CoherentXBarParams *p);

    virtual ~CoherentXBar();

    virtual void regStats();
};

#endif //__MEM_COHERENT_XBAR_HH__