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diff --git a/src/mem/coherent_xbar.hh b/src/mem/coherent_xbar.hh new file mode 100644 index 000000000..fd4dd1cca --- /dev/null +++ b/src/mem/coherent_xbar.hh @@ -0,0 +1,397 @@ +/* + * Copyright (c) 2011-2014 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 + */ + +/** + * @file + * Declaration of a coherent crossbar. + */ + +#ifndef __MEM_COHERENT_XBAR_HH__ +#define __MEM_COHERENT_XBAR_HH__ + +#include "base/hashmap.hh" +#include "mem/snoop_filter.hh" +#include "mem/xbar.hh" +#include "params/CoherentXBar.hh" + +/** + * A coherent crossbar connects a number of (potentially) snooping + * masters and slaves, and routes the request and response packets + * based on the address, and also forwards all requests to the + * snoopers and deals with the snoop responses. + * + * The coherent crossbar can be used as a template for modelling QPI, + * HyperTransport, ACE and coherent OCP buses, and is typically used + * for the L1-to-L2 buses and as the main system interconnect. @sa + * \ref gem5MemorySystem "gem5 Memory System" + */ +class CoherentXBar : public BaseXBar +{ + + protected: + + /** + * Declare the layers of this crossbar, one vector for requests, + * one for responses, and one for snoop responses + */ + typedef Layer<SlavePort,MasterPort> ReqLayer; + typedef Layer<MasterPort,SlavePort> RespLayer; + typedef Layer<SlavePort,MasterPort> SnoopLayer; + std::vector<ReqLayer*> reqLayers; + std::vector<RespLayer*> respLayers; + std::vector<SnoopLayer*> snoopLayers; + + /** + * Declaration of the coherent crossbar slave port type, one will + * be instantiated for each of the master ports connecting to the + * crossbar. + */ + class CoherentXBarSlavePort : public SlavePort + { + + private: + + /** A reference to the crossbar to which this port belongs. */ + CoherentXBar &xbar; + + public: + + CoherentXBarSlavePort(const std::string &_name, + CoherentXBar &_xbar, PortID _id) + : SlavePort(_name, &_xbar, _id), xbar(_xbar) + { } + + protected: + + /** + * When receiving a timing request, pass it to the crossbar. + */ + virtual bool recvTimingReq(PacketPtr pkt) + { return xbar.recvTimingReq(pkt, id); } + + /** + * When receiving a timing snoop response, pass it to the crossbar. + */ + virtual bool recvTimingSnoopResp(PacketPtr pkt) + { return xbar.recvTimingSnoopResp(pkt, id); } + + /** + * When receiving an atomic request, pass it to the crossbar. + */ + virtual Tick recvAtomic(PacketPtr pkt) + { return xbar.recvAtomic(pkt, id); } + + /** + * When receiving a functional request, pass it to the crossbar. + */ + virtual void recvFunctional(PacketPtr pkt) + { xbar.recvFunctional(pkt, id); } + + /** + * When receiving a retry, pass it to the crossbar. + */ + virtual void recvRetry() + { panic("Crossbar slave ports should never retry.\n"); } + + /** + * Return the union of all adress ranges seen by this crossbar. + */ + virtual AddrRangeList getAddrRanges() const + { return xbar.getAddrRanges(); } + + }; + + /** + * Declaration of the coherent crossbar master port type, one will be + * instantiated for each of the slave interfaces connecting to the + * crossbar. + */ + class CoherentXBarMasterPort : public MasterPort + { + private: + /** A reference to the crossbar to which this port belongs. */ + CoherentXBar &xbar; + + public: + + CoherentXBarMasterPort(const std::string &_name, + CoherentXBar &_xbar, PortID _id) + : MasterPort(_name, &_xbar, _id), xbar(_xbar) + { } + + protected: + + /** + * Determine if this port should be considered a snooper. For + * a coherent crossbar master port this is always true. + * + * @return a boolean that is true if this port is snooping + */ + virtual bool isSnooping() const + { return true; } + + /** + * When receiving a timing response, pass it to the crossbar. + */ + virtual bool recvTimingResp(PacketPtr pkt) + { return xbar.recvTimingResp(pkt, id); } + + /** + * When receiving a timing snoop request, pass it to the crossbar. + */ + virtual void recvTimingSnoopReq(PacketPtr pkt) + { return xbar.recvTimingSnoopReq(pkt, id); } + + /** + * When receiving an atomic snoop request, pass it to the crossbar. + */ + virtual Tick recvAtomicSnoop(PacketPtr pkt) + { return xbar.recvAtomicSnoop(pkt, id); } + + /** + * When receiving a functional snoop request, pass it to the crossbar. + */ + virtual void recvFunctionalSnoop(PacketPtr pkt) + { xbar.recvFunctionalSnoop(pkt, id); } + + /** When reciving a range change from the peer port (at id), + pass it to the crossbar. */ + virtual void recvRangeChange() + { xbar.recvRangeChange(id); } + + /** When reciving a retry from the peer port (at id), + pass it to the crossbar. */ + virtual void recvRetry() + { xbar.recvRetry(id); } + + }; + + /** + * Internal class to bridge between an incoming snoop response + * from a slave port and forwarding it through an outgoing slave + * port. It is effectively a dangling master port. + */ + class SnoopRespPort : public MasterPort + { + + private: + + /** The port which we mirror internally. */ + SlavePort& slavePort; + + public: + + /** + * Create a snoop response port that mirrors a given slave port. + */ + SnoopRespPort(SlavePort& slave_port, CoherentXBar& _xbar) : + MasterPort(slave_port.name() + ".snoopRespPort", &_xbar), + slavePort(slave_port) { } + + /** + * Override the sending of retries and pass them on through + * the mirrored slave port. + */ + void sendRetry() { + slavePort.sendRetry(); + } + + /** + * Provided as necessary. + */ + void recvRetry() { panic("SnoopRespPort should never see retry\n"); } + + /** + * Provided as necessary. + */ + bool recvTimingResp(PacketPtr pkt) + { + panic("SnoopRespPort should never see timing response\n"); + return false; + } + + }; + + std::vector<SnoopRespPort*> snoopRespPorts; + + std::vector<SlavePort*> snoopPorts; + + /** + * Store the outstanding requests so we can determine which ones + * we generated and which ones were merely forwarded. This is used + * in the coherent crossbar when coherency responses come back. + */ + m5::hash_set<RequestPtr> outstandingReq; + + /** + * Keep a pointer to the system to be allow to querying memory system + * properties. + */ + System *system; + + /** A snoop filter that tracks cache line residency and can restrict the + * broadcast needed for probes. NULL denotes an absent filter. */ + SnoopFilter *snoopFilter; + + /** Function called by the port when the crossbar is recieving a Timing + request packet.*/ + bool recvTimingReq(PacketPtr pkt, PortID slave_port_id); + + /** Function called by the port when the crossbar is recieving a Timing + response packet.*/ + bool recvTimingResp(PacketPtr pkt, PortID master_port_id); + + /** Function called by the port when the crossbar is recieving a timing + snoop request.*/ + void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id); + + /** Function called by the port when the crossbar is recieving a timing + snoop response.*/ + bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id); + + /** Timing function called by port when it is once again able to process + * requests. */ + void recvRetry(PortID master_port_id); + + /** + * Forward a timing packet to our snoopers, potentially excluding + * one of the connected coherent masters to avoid sending a packet + * back to where it came from. + * + * @param pkt Packet to forward + * @param exclude_slave_port_id Id of slave port to exclude + */ + void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) { + forwardTiming(pkt, exclude_slave_port_id, snoopPorts); + } + + /** + * Forward a timing packet to a selected list of snoopers, potentially + * excluding one of the connected coherent masters to avoid sending a packet + * back to where it came from. + * + * @param pkt Packet to forward + * @param exclude_slave_port_id Id of slave port to exclude + * @param dests Vector of destination ports for the forwarded pkt + */ + void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id, + const std::vector<SlavePort*>& dests); + + /** Function called by the port when the crossbar is recieving a Atomic + transaction.*/ + Tick recvAtomic(PacketPtr pkt, PortID slave_port_id); + + /** Function called by the port when the crossbar is recieving an + atomic snoop transaction.*/ + Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id); + + /** + * Forward an atomic packet to our snoopers, potentially excluding + * one of the connected coherent masters to avoid sending a packet + * back to where it came from. + * + * @param pkt Packet to forward + * @param exclude_slave_port_id Id of slave port to exclude + * + * @return a pair containing the snoop response and snoop latency + */ + std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt, + PortID exclude_slave_port_id) + { + return forwardAtomic(pkt, exclude_slave_port_id, InvalidPortID, snoopPorts); + } + + /** + * Forward an atomic packet to a selected list of snoopers, potentially + * excluding one of the connected coherent masters to avoid sending a packet + * back to where it came from. + * + * @param pkt Packet to forward + * @param exclude_slave_port_id Id of slave port to exclude + * @param source_master_port_id Id of the master port for snoops from below + * @param dests Vector of destination ports for the forwarded pkt + * + * @return a pair containing the snoop response and snoop latency + */ + std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt, + PortID exclude_slave_port_id, + PortID source_master_port_id, + const std::vector<SlavePort*>& dests); + + /** Function called by the port when the crossbar is recieving a Functional + transaction.*/ + void recvFunctional(PacketPtr pkt, PortID slave_port_id); + + /** Function called by the port when the crossbar is recieving a functional + snoop transaction.*/ + void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id); + + /** + * Forward a functional packet to our snoopers, potentially + * excluding one of the connected coherent masters to avoid + * sending a packet back to where it came from. + * + * @param pkt Packet to forward + * @param exclude_slave_port_id Id of slave port to exclude + */ + void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id); + + Stats::Scalar snoops; + Stats::Distribution snoopFanout; + + public: + + virtual void init(); + + CoherentXBar(const CoherentXBarParams *p); + + virtual ~CoherentXBar(); + + unsigned int drain(DrainManager *dm); + + virtual void regStats(); +}; + +#endif //__MEM_COHERENT_XBAR_HH__ |