| /* |
| * Copyright (c) 2013 - 2016 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. |
| * |
| * 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. |
| */ |
| |
| #ifndef __CPU_TRACE_TRACE_CPU_HH__ |
| #define __CPU_TRACE_TRACE_CPU_HH__ |
| |
| #include <cstdint> |
| #include <list> |
| #include <queue> |
| #include <set> |
| #include <unordered_map> |
| |
| #include "base/statistics.hh" |
| #include "cpu/base.hh" |
| #include "debug/TraceCPUData.hh" |
| #include "debug/TraceCPUInst.hh" |
| #include "params/TraceCPU.hh" |
| #include "proto/inst_dep_record.pb.h" |
| #include "proto/packet.pb.h" |
| #include "proto/protoio.hh" |
| #include "sim/sim_events.hh" |
| |
| namespace gem5 |
| { |
| |
| /** |
| * The trace cpu replays traces generated using the elastic trace probe |
| * attached to the O3 CPU model. The elastic trace is an execution trace with |
| * register data dependencies and ordering dependencies annotated to it. The |
| * trace cpu also replays a fixed timestamp fetch trace that is also generated |
| * by the elastic trace probe. This trace cpu model aims at achieving faster |
| * simulation compared to the detailed cpu model and good correlation when the |
| * same trace is used for playback on different memory sub-systems. |
| * |
| * The TraceCPU inherits from BaseCPU so some virtual methods need to be |
| * defined. It has two port subclasses inherited from RequestPort for |
| * instruction and data ports. It issues the memory requests deducing the |
| * timing from the trace and without performing real execution of micro-ops. As |
| * soon as the last dependency for an instruction is complete, its |
| * computational delay, also provided in the input trace is added. The |
| * dependency-free nodes are maintained in a list, called 'ReadyList', ordered |
| * by ready time. Instructions which depend on load stall until the responses |
| * for read requests are received thus achieving elastic replay. If the |
| * dependency is not found when adding a new node, it is assumed complete. |
| * Thus, if this node is found to be completely dependency-free its issue time |
| * is calculated and it is added to the ready list immediately. This is |
| * encapsulated in the subclass ElasticDataGen. |
| * |
| * If ready nodes are issued in an unconstrained way there can be more nodes |
| * outstanding which results in divergence in timing compared to the O3CPU. |
| * Therefore, the Trace CPU also models hardware resources. A sub-class to |
| * model hardware resources contains the maximum sizes of load buffer, store |
| * buffer and ROB. If resources are not available, the node is not issued. Such |
| * nodes that are pending issue are held in the 'depFreeQueue' structure. |
| * |
| * Modeling the ROB size in the Trace CPU as a resource limitation is arguably |
| * the most important parameter of all resources. The ROB occupancy is |
| * estimated using the newly added field 'robNum'. We need to use ROB number as |
| * sequence number is at times much higher due to squashing and trace replay is |
| * focused on correct path modeling. |
| * |
| * A map called 'inFlightNodes' is added to track nodes that are not only in |
| * the readyList but also load nodes that are executed (and thus removed from |
| * readyList) but are not complete. ReadyList handles what and when to execute |
| * next node while the inFlightNodes is used for resource modelling. The oldest |
| * ROB number is updated when any node occupies the ROB or when an entry in the |
| * ROB is released. The ROB occupancy is equal to the difference in the ROB |
| * number of the newly dependency-free node and the oldest ROB number in |
| * flight. |
| * |
| * If no node depends on a non load/store node then there is no reason to |
| * track it in the dependency graph. We filter out such nodes but count them |
| * and add a weight field to the subsequent node that we do include in the |
| * trace. The weight field is used to model ROB occupancy during replay. |
| * |
| * The depFreeQueue is chosen to be FIFO so that child nodes which are in |
| * program order get pushed into it in that order and thus issued in program |
| * order, like in the O3CPU. This is also why the dependents is made a |
| * sequential container, std::set to std::vector. We only check head of the |
| * depFreeQueue as nodes are issued in order and blocking on head models that |
| * better than looping the entire queue. An alternative choice would be to |
| * inspect top N pending nodes where N is the issue-width. This is left for |
| * future as the timing correlation looks good as it is. |
| * |
| * At the start of an execution event, first we attempt to issue such pending |
| * nodes by checking if appropriate resources have become available. If yes, we |
| * compute the execute tick with respect to the time then. Then we proceed to |
| * complete nodes from the readyList. |
| * |
| * When a read response is received, sometimes a dependency on it that was |
| * supposed to be released when it was issued is still not released. This |
| * occurs because the dependent gets added to the graph after the read was |
| * sent. So the check is made less strict and the dependency is marked complete |
| * on read response instead of insisting that it should have been removed on |
| * read sent. |
| * |
| * There is a check for requests spanning two cache lines as this condition |
| * triggers an assert fail in the L1 cache. If it does then truncate the size |
| * to access only until the end of that line and ignore the remainder. |
| * Strictly-ordered requests are skipped and the dependencies on such requests |
| * are handled by simply marking them complete immediately. |
| * |
| * A CountedExitEvent that contains a static int belonging to the Trace CPU |
| * class as a down counter is used to implement multi Trace CPU simulation |
| * exit. |
| */ |
| |
| class TraceCPU : public BaseCPU |
| { |
| |
| public: |
| TraceCPU(const TraceCPUParams ¶ms); |
| |
| void init(); |
| |
| /** |
| * This is a pure virtual function in BaseCPU. As we don't know how many |
| * insts are in the trace but only know how how many micro-ops are we |
| * cannot count this stat. |
| * |
| * @return 0 |
| */ |
| Counter totalInsts() const { return 0; } |
| |
| /** |
| * Return totalOps as the number of committed micro-ops plus the |
| * speculatively issued loads that are modelled in the TraceCPU replay. |
| * |
| * @return number of micro-ops i.e. nodes in the elastic data generator |
| */ |
| Counter totalOps() const { return traceStats.numOps.value(); } |
| |
| /* |
| * Set the no. of ops when elastic data generator completes executing a |
| * node. |
| */ |
| void updateNumOps(uint64_t rob_num); |
| |
| /* Pure virtual function in BaseCPU. Do nothing. */ |
| void wakeup(ThreadID tid=0) { return; } |
| |
| /* |
| * When resuming from checkpoint in FS mode, the TraceCPU takes over from |
| * the old cpu. This function overrides the takeOverFrom() function in the |
| * BaseCPU. It unbinds the ports of the old CPU and binds the ports of the |
| * TraceCPU. |
| */ |
| void takeOverFrom(BaseCPU *oldCPU); |
| |
| /** |
| * When instruction cache port receives a retry, schedule event |
| * icacheNextEvent. |
| */ |
| void icacheRetryRecvd(); |
| |
| /** |
| * When data cache port receives a retry, schedule event |
| * dcacheNextEvent. |
| */ |
| void dcacheRetryRecvd(); |
| |
| /** |
| * When data cache port receives a response, this calls the dcache |
| * generator method handle to complete the load writeback. |
| * |
| * @param pkt Pointer to packet received |
| */ |
| void dcacheRecvTimingResp(PacketPtr pkt); |
| |
| /** |
| * Schedule event dcacheNextEvent at the given tick |
| * |
| * @param when Tick at which to schedule event |
| */ |
| void schedDcacheNextEvent(Tick when); |
| |
| protected: |
| |
| /** |
| * IcachePort class that interfaces with L1 Instruction Cache. |
| */ |
| class IcachePort : public RequestPort |
| { |
| public: |
| /** Default constructor. */ |
| IcachePort(TraceCPU* _cpu) : |
| RequestPort(_cpu->name() + ".icache_port", _cpu), owner(_cpu) |
| {} |
| |
| public: |
| /** |
| * Receive the timing reponse and simply delete the packet since |
| * instruction fetch requests are issued as per the timing in the trace |
| * and responses are ignored. |
| * |
| * @param pkt Pointer to packet received |
| * @return true |
| */ |
| bool recvTimingResp(PacketPtr pkt); |
| |
| /** |
| * Required functionally but do nothing. |
| * |
| * @param pkt Pointer to packet received |
| */ |
| void recvTimingSnoopReq(PacketPtr pkt) {} |
| |
| /** |
| * Handle a retry signalled by the cache if instruction read failed in |
| * the first attempt. |
| */ |
| void recvReqRetry(); |
| |
| private: |
| TraceCPU* owner; |
| }; |
| |
| /** |
| * DcachePort class that interfaces with L1 Data Cache. |
| */ |
| class DcachePort : public RequestPort |
| { |
| |
| public: |
| /** Default constructor. */ |
| DcachePort(TraceCPU* _cpu) : |
| RequestPort(_cpu->name() + ".dcache_port", _cpu), owner(_cpu) |
| {} |
| |
| public: |
| |
| /** |
| * Receive the timing reponse and call dcacheRecvTimingResp() method |
| * of the dcacheGen to handle completing the load |
| * |
| * @param pkt Pointer to packet received |
| * @return true |
| */ |
| bool recvTimingResp(PacketPtr pkt); |
| |
| /** |
| * Required functionally but do nothing. |
| * |
| * @param pkt Pointer to packet received |
| */ |
| void recvTimingSnoopReq(PacketPtr pkt) {} |
| |
| /** |
| * Required functionally but do nothing. |
| * |
| * @param pkt Pointer to packet received |
| */ |
| void recvFunctionalSnoop(PacketPtr pkt) {} |
| |
| /** |
| * Handle a retry signalled by the cache if data access failed in the |
| * first attempt. |
| */ |
| void recvReqRetry(); |
| |
| /** |
| * Required functionally. |
| * |
| * @return true since we have to snoop |
| */ |
| bool isSnooping() const { return true; } |
| |
| private: |
| TraceCPU* owner; |
| }; |
| |
| /** Port to connect to L1 instruction cache. */ |
| IcachePort icachePort; |
| |
| /** Port to connect to L1 data cache. */ |
| DcachePort dcachePort; |
| |
| /** Requestor id for instruction read requests. */ |
| const RequestorID instRequestorID; |
| |
| /** Requestor id for data read and write requests. */ |
| const RequestorID dataRequestorID; |
| |
| /** File names for input instruction and data traces. */ |
| std::string instTraceFile, dataTraceFile; |
| |
| /** |
| * Generator to read protobuf trace containing memory requests at fixed |
| * timestamps, perform flow control and issue memory requests. If L1 cache |
| * port sends packet succesfully, determine the tick to send the next |
| * packet else wait for retry from cache. |
| */ |
| class FixedRetryGen |
| { |
| |
| private: |
| |
| /** |
| * This struct stores a line in the trace file. |
| */ |
| struct TraceElement |
| { |
| |
| /** Specifies if the request is to be a read or a write */ |
| MemCmd cmd; |
| |
| /** The address for the request */ |
| Addr addr; |
| |
| /** The size of the access for the request */ |
| Addr blocksize; |
| |
| /** The time at which the request should be sent */ |
| Tick tick; |
| |
| /** Potential request flags to use */ |
| Request::FlagsType flags; |
| |
| /** Instruction PC */ |
| Addr pc; |
| |
| /** |
| * Check validity of this element. |
| * |
| * @return if this element is valid |
| */ |
| bool isValid() const { return cmd != MemCmd::InvalidCmd; } |
| |
| /** |
| * Make this element invalid. |
| */ |
| void clear() { cmd = MemCmd::InvalidCmd; } |
| }; |
| |
| /** |
| * The InputStream encapsulates a trace file and the |
| * internal buffers and populates TraceElements based on |
| * the input. |
| */ |
| class InputStream |
| { |
| private: |
| // Input file stream for the protobuf trace |
| ProtoInputStream trace; |
| |
| public: |
| /** |
| * Create a trace input stream for a given file name. |
| * |
| * @param filename Path to the file to read from |
| */ |
| InputStream(const std::string& filename); |
| |
| /** |
| * Reset the stream such that it can be played once |
| * again. |
| */ |
| void reset(); |
| |
| /** |
| * Attempt to read a trace element from the stream, |
| * and also notify the caller if the end of the file |
| * was reached. |
| * |
| * @param element Trace element to populate |
| * @return True if an element could be read successfully |
| */ |
| bool read(TraceElement* element); |
| }; |
| |
| public: |
| /* Constructor */ |
| FixedRetryGen(TraceCPU& _owner, const std::string& _name, |
| RequestPort& _port, RequestorID requestor_id, |
| const std::string& trace_file) : |
| owner(_owner), |
| port(_port), |
| requestorId(requestor_id), |
| trace(trace_file), |
| genName(owner.name() + ".fixedretry." + _name), |
| retryPkt(nullptr), |
| delta(0), |
| traceComplete(false), fixedStats(&_owner, _name) |
| { |
| } |
| |
| /** |
| * Called from TraceCPU init(). Reads the first message from the |
| * input trace file and returns the send tick. |
| * |
| * @return Tick when first packet must be sent |
| */ |
| Tick init(); |
| |
| /** |
| * This tries to send current or retry packet and returns true if |
| * successfull. It calls nextExecute() to read next message. |
| * |
| * @return bool true if packet is sent successfully |
| */ |
| bool tryNext(); |
| |
| /** Returns name of the FixedRetryGen instance. */ |
| const std::string& name() const { return genName; } |
| |
| /** |
| * Creates a new request assigning the request parameters passed by the |
| * arguments. Calls the port's sendTimingReq() and returns true if |
| * the packet was sent succesfully. It is called by tryNext() |
| * |
| * @param addr address of request |
| * @param size size of request |
| * @param cmd if it is a read or write request |
| * @param flags associated request flags |
| * @param pc instruction PC that generated the request |
| * |
| * @return true if packet was sent successfully |
| */ |
| bool send(Addr addr, unsigned size, const MemCmd& cmd, |
| Request::FlagsType flags, Addr pc); |
| |
| /** Exit the FixedRetryGen. */ |
| void exit(); |
| |
| /** |
| * Reads a line of the trace file. Returns the tick |
| * when the next request should be generated. If the end |
| * of the file has been reached, it returns false. |
| * |
| * @return bool false id end of file has been reached |
| */ |
| bool nextExecute(); |
| |
| /** |
| * Returns the traceComplete variable which is set when end of the |
| * input trace file is reached. |
| * |
| * @return bool true if traceComplete is set, false otherwise. |
| */ |
| bool isTraceComplete() { return traceComplete; } |
| |
| int64_t tickDelta() { return delta; } |
| |
| private: |
| /** Reference of the TraceCPU. */ |
| TraceCPU& owner; |
| |
| /** Reference of the port to be used to issue memory requests. */ |
| RequestPort& port; |
| |
| /** RequestorID used for the requests being sent. */ |
| const RequestorID requestorId; |
| |
| /** Input stream used for reading the input trace file. */ |
| InputStream trace; |
| |
| /** String to store the name of the FixedRetryGen. */ |
| std::string genName; |
| |
| /** PacketPtr used to store the packet to retry. */ |
| PacketPtr retryPkt; |
| |
| /** |
| * Stores the difference in the send ticks of the current and last |
| * packets. Keeping this signed to check overflow to a negative value |
| * which will be caught by assert(delta > 0) |
| */ |
| int64_t delta; |
| |
| /** |
| * Set to true when end of trace is reached. |
| */ |
| bool traceComplete; |
| |
| /** Store an element read from the trace to send as the next packet. */ |
| TraceElement currElement; |
| protected: |
| struct FixedRetryGenStatGroup : public statistics::Group |
| { |
| /** name is the extension to the name for these stats */ |
| FixedRetryGenStatGroup(statistics::Group *parent, |
| const std::string& _name); |
| /** Stats for instruction accesses replayed. */ |
| statistics::Scalar numSendAttempted; |
| statistics::Scalar numSendSucceeded; |
| statistics::Scalar numSendFailed; |
| statistics::Scalar numRetrySucceeded; |
| /** Last simulated tick by the FixedRetryGen */ |
| statistics::Scalar instLastTick; |
| } fixedStats; |
| |
| }; |
| |
| /** |
| * The elastic data memory request generator to read protobuf trace |
| * containing execution trace annotated with data and ordering |
| * dependencies. It deduces the time at which to send a load/store request |
| * by tracking the dependencies. It attempts to send a memory request for a |
| * load/store without performing real execution of micro-ops. If L1 cache |
| * port sends packet succesfully, the generator checks which instructions |
| * became dependency free as a result of this and schedules an event |
| * accordingly. If it fails to send the packet, it waits for a retry from |
| * the cache. |
| */ |
| class ElasticDataGen |
| { |
| private: |
| /** Node sequence number type. */ |
| typedef uint64_t NodeSeqNum; |
| |
| /** Node ROB number type. */ |
| typedef uint64_t NodeRobNum; |
| |
| typedef ProtoMessage::InstDepRecord::RecordType RecordType; |
| typedef ProtoMessage::InstDepRecord Record; |
| |
| /** |
| * The struct GraphNode stores an instruction in the trace file. The |
| * format of the trace file favours constructing a dependency graph of |
| * the execution and this struct is used to encapsulate the request |
| * data as well as pointers to its dependent GraphNodes. |
| */ |
| class GraphNode |
| { |
| public: |
| /** Typedef for the list containing the ROB dependencies */ |
| typedef std::list<NodeSeqNum> RobDepList; |
| |
| /** Typedef for the list containing the register dependencies */ |
| typedef std::list<NodeSeqNum> RegDepList; |
| |
| /** Instruction sequence number */ |
| NodeSeqNum seqNum; |
| |
| /** ROB occupancy number */ |
| NodeRobNum robNum; |
| |
| /** |
| * Type of the node corresponding to the instruction modeled by |
| * it. |
| */ |
| RecordType type; |
| |
| /** The address for the request if any */ |
| Addr physAddr; |
| |
| /** The virtual address for the request if any */ |
| Addr virtAddr; |
| |
| /** Size of request if any */ |
| uint32_t size; |
| |
| /** Request flags if any */ |
| Request::Flags flags; |
| |
| /** Instruction PC */ |
| Addr pc; |
| |
| /** List of order dependencies. */ |
| RobDepList robDep; |
| |
| /** Computational delay */ |
| uint64_t compDelay; |
| |
| /** |
| * List of register dependencies (incoming) if any. Maximum number |
| * of source registers used to set maximum size of the array |
| */ |
| RegDepList regDep; |
| |
| /** |
| * A vector of nodes dependent (outgoing) on this node. A |
| * sequential container is chosen because when dependents become |
| * free, they attempt to issue in program order. |
| */ |
| std::vector<GraphNode *> dependents; |
| |
| /** Is the node a load */ |
| bool isLoad() const { return (type == Record::LOAD); } |
| |
| /** Is the node a store */ |
| bool isStore() const { return (type == Record::STORE); } |
| |
| /** Is the node a compute (non load/store) node */ |
| bool isComp() const { return (type == Record::COMP); } |
| |
| /** Remove completed instruction from register dependency array */ |
| bool removeRegDep(NodeSeqNum reg_dep); |
| |
| /** Remove completed instruction from order dependency array */ |
| bool removeRobDep(NodeSeqNum rob_dep); |
| |
| /** Check for all dependencies on completed inst */ |
| bool removeDepOnInst(NodeSeqNum done_seq_num); |
| |
| /** Return true if node has a request which is strictly ordered */ |
| bool |
| isStrictlyOrdered() const |
| { |
| return (flags.isSet(Request::STRICT_ORDER)); |
| } |
| /** |
| * Write out element in trace-compatible format using debug flag |
| * TraceCPUData. |
| */ |
| void writeElementAsTrace() const; |
| |
| /** Return string specifying the type of the node */ |
| std::string typeToStr() const; |
| }; |
| |
| /** Struct to store a ready-to-execute node and its execution tick. */ |
| struct ReadyNode |
| { |
| /** The sequence number of the ready node */ |
| NodeSeqNum seqNum; |
| |
| /** The tick at which the ready node must be executed */ |
| Tick execTick; |
| }; |
| |
| /** |
| * The HardwareResource class models structures that hold the in-flight |
| * nodes. When a node becomes dependency free, first check if resources |
| * are available to issue it. |
| */ |
| class HardwareResource |
| { |
| public: |
| /** |
| * Constructor that initializes the sizes of the structures. |
| * |
| * @param max_rob size of the Reorder Buffer |
| * @param max_stores size of Store Buffer |
| * @param max_loads size of Load Buffer |
| */ |
| HardwareResource(uint16_t max_rob, uint16_t max_stores, |
| uint16_t max_loads); |
| |
| /** |
| * Occupy appropriate structures for an issued node. |
| * |
| * @param node_ptr pointer to the issued node |
| */ |
| void occupy(const GraphNode* new_node); |
| |
| /** |
| * Release appropriate structures for a completed node. |
| * |
| * @param node_ptr pointer to the completed node |
| */ |
| void release(const GraphNode* done_node); |
| |
| /** Release store buffer entry for a completed store */ |
| void releaseStoreBuffer(); |
| |
| /** |
| * Check if structures required to issue a node are free. |
| * |
| * @param node_ptr pointer to the node ready to issue |
| * @return true if resources are available |
| */ |
| bool isAvailable(const GraphNode* new_node) const; |
| |
| /** |
| * Check if there are any outstanding requests, i.e. requests for |
| * which we are yet to receive a response. |
| * |
| * @return true if there is at least one read or write request |
| * outstanding |
| */ |
| bool awaitingResponse() const; |
| |
| /** Print resource occupancy for debugging. */ |
| void printOccupancy(); |
| |
| private: |
| /** |
| * The size of the ROB used to throttle the max. number of |
| * in-flight nodes. |
| */ |
| const uint16_t sizeROB; |
| |
| /** |
| * The size of store buffer. This is used to throttle the max. |
| * number of in-flight stores. |
| */ |
| const uint16_t sizeStoreBuffer; |
| |
| /** |
| * The size of load buffer. This is used to throttle the max. |
| * number of in-flight loads. |
| */ |
| const uint16_t sizeLoadBuffer; |
| |
| /** |
| * A map from the sequence number to the ROB number of the in- |
| * flight nodes. This includes all nodes that are in the readyList |
| * plus the loads for which a request has been sent which are not |
| * present in the readyList. But such loads are not yet complete |
| * and thus occupy resources. We need to query the oldest in-flight |
| * node and since a map container keeps all its keys sorted using |
| * the less than criterion, the first element is the in-flight node |
| * with the least sequence number, i.e. the oldest in-flight node. |
| */ |
| std::map<NodeSeqNum, NodeRobNum> inFlightNodes; |
| |
| /** The ROB number of the oldest in-flight node */ |
| NodeRobNum oldestInFlightRobNum; |
| |
| /** Number of ready loads for which request may or may not be |
| * sent. |
| */ |
| uint16_t numInFlightLoads; |
| |
| /** Number of ready stores for which request may or may not be |
| * sent. |
| */ |
| uint16_t numInFlightStores; |
| }; |
| |
| /** |
| * The InputStream encapsulates a trace file and the |
| * internal buffers and populates GraphNodes based on |
| * the input. |
| */ |
| class InputStream |
| { |
| private: |
| /** Input file stream for the protobuf trace */ |
| ProtoInputStream trace; |
| |
| /** |
| * A multiplier for the compute delays in the trace to modulate |
| * the Trace CPU frequency either up or down. The Trace CPU's |
| * clock domain frequency must also be set to match the expected |
| * result of frequency scaling. |
| */ |
| const double timeMultiplier; |
| |
| /** Count of committed ops read from trace plus the filtered ops */ |
| uint64_t microOpCount; |
| |
| /** |
| * The window size that is read from the header of the protobuf |
| * trace and used to process the dependency trace |
| */ |
| uint32_t windowSize; |
| |
| public: |
| /** |
| * Create a trace input stream for a given file name. |
| * |
| * @param filename Path to the file to read from |
| * @param time_multiplier used to scale the compute delays |
| */ |
| InputStream(const std::string& filename, |
| const double time_multiplier); |
| |
| /** |
| * Reset the stream such that it can be played once |
| * again. |
| */ |
| void reset(); |
| |
| /** |
| * Attempt to read a trace element from the stream, |
| * and also notify the caller if the end of the file |
| * was reached. |
| * |
| * @param element Trace element to populate |
| * @param size of register dependency array stored in the element |
| * @return True if an element could be read successfully |
| */ |
| bool read(GraphNode* element); |
| |
| /** Get window size from trace */ |
| uint32_t getWindowSize() const { return windowSize; } |
| |
| /** Get number of micro-ops modelled in the TraceCPU replay */ |
| uint64_t getMicroOpCount() const { return microOpCount; } |
| }; |
| |
| public: |
| /* Constructor */ |
| ElasticDataGen(TraceCPU& _owner, const std::string& _name, |
| RequestPort& _port, RequestorID requestor_id, |
| const std::string& trace_file, |
| const TraceCPUParams ¶ms) : |
| owner(_owner), |
| port(_port), |
| requestorId(requestor_id), |
| trace(trace_file, 1.0 / params.freqMultiplier), |
| genName(owner.name() + ".elastic." + _name), |
| retryPkt(nullptr), |
| traceComplete(false), |
| nextRead(false), |
| execComplete(false), |
| windowSize(trace.getWindowSize()), |
| hwResource(params.sizeROB, params.sizeStoreBuffer, |
| params.sizeLoadBuffer), elasticStats(&_owner, _name) |
| { |
| DPRINTF(TraceCPUData, "Window size in the trace is %d.\n", |
| windowSize); |
| } |
| |
| /** |
| * Called from TraceCPU init(). Reads the first message from the |
| * input trace file and returns the send tick. |
| * |
| * @return Tick when first packet must be sent |
| */ |
| Tick init(); |
| |
| /** |
| * Adjust traceOffset based on what TraceCPU init() determines on |
| * comparing the offsets in the fetch request and elastic traces. |
| * |
| * @param trace_offset trace offset set by comparing both traces |
| */ |
| void adjustInitTraceOffset(Tick& offset); |
| |
| /** Returns name of the ElasticDataGen instance. */ |
| const std::string& name() const { return genName; } |
| |
| /** Exit the ElasticDataGen. */ |
| void exit(); |
| |
| /** |
| * Reads a line of the trace file. Returns the tick when the next |
| * request should be generated. If the end of the file has been |
| * reached, it returns false. |
| * |
| * @return bool false if end of file has been reached else true |
| */ |
| bool readNextWindow(); |
| |
| /** |
| * Iterate over the dependencies of a new node and add the new node |
| * to the list of dependents of the parent node. |
| * |
| * @param new_node new node to add to the graph |
| * @tparam dep_list the dependency list of type rob or register, |
| * that is to be iterated, and may get modified |
| */ |
| template<typename T> |
| void addDepsOnParent(GraphNode *new_node, T& dep_list); |
| |
| /** |
| * This is the main execute function which consumes nodes from the |
| * sorted readyList. First attempt to issue the pending dependency-free |
| * nodes held in the depFreeQueue. Insert the ready-to-issue nodes into |
| * the readyList. Then iterate through the readyList and when a node |
| * has its execute tick equal to curTick(), execute it. If the node is |
| * a load or a store call executeMemReq() and if it is neither, simply |
| * mark it complete. |
| */ |
| void execute(); |
| |
| /** |
| * Creates a new request for a load or store assigning the request |
| * parameters. Calls the port's sendTimingReq() and returns a packet |
| * if the send failed so that it can be saved for a retry. |
| * |
| * @param node_ptr pointer to the load or store node to be executed |
| * |
| * @return packet pointer if the request failed and nullptr if it was |
| * sent successfully |
| */ |
| PacketPtr executeMemReq(GraphNode* node_ptr); |
| |
| /** |
| * Add a ready node to the readyList. When inserting, ensure the nodes |
| * are sorted in ascending order of their execute ticks. |
| * |
| * @param seq_num seq. num of ready node |
| * @param exec_tick the execute tick of the ready node |
| */ |
| void addToSortedReadyList(NodeSeqNum seq_num, Tick exec_tick); |
| |
| /** Print readyList for debugging using debug flag TraceCPUData. */ |
| void printReadyList(); |
| |
| /** |
| * When a load writeback is received, that is when the load completes, |
| * release the dependents on it. This is called from the dcache port |
| * recvTimingResp(). |
| */ |
| void completeMemAccess(PacketPtr pkt); |
| |
| /** |
| * Returns the execComplete variable which is set when the last |
| * node is executed. |
| * |
| * @return bool true if execComplete is set, false otherwise. |
| */ |
| bool isExecComplete() const { return execComplete; } |
| |
| /** |
| * Attempts to issue a node once the node's source dependencies are |
| * complete. If resources are available then add it to the readyList, |
| * otherwise the node is not issued and is stored in depFreeQueue |
| * until resources become available. |
| * |
| * @param node_ptr pointer to node to be issued |
| * @param first true if this is the first attempt to issue this node |
| * @return true if node was added to readyList |
| */ |
| bool checkAndIssue(const GraphNode* node_ptr, bool first=true); |
| |
| /** Get number of micro-ops modelled in the TraceCPU replay */ |
| uint64_t getMicroOpCount() const { return trace.getMicroOpCount(); } |
| |
| private: |
| /** Reference of the TraceCPU. */ |
| TraceCPU& owner; |
| |
| /** Reference of the port to be used to issue memory requests. */ |
| RequestPort& port; |
| |
| /** RequestorID used for the requests being sent. */ |
| const RequestorID requestorId; |
| |
| /** Input stream used for reading the input trace file. */ |
| InputStream trace; |
| |
| /** String to store the name of the FixedRetryGen. */ |
| std::string genName; |
| |
| /** PacketPtr used to store the packet to retry. */ |
| PacketPtr retryPkt; |
| |
| /** Set to true when end of trace is reached. */ |
| bool traceComplete; |
| |
| /** Set to true when the next window of instructions need to be read */ |
| bool nextRead; |
| |
| /** Set true when execution of trace is complete */ |
| bool execComplete; |
| |
| /** |
| * Window size within which to check for dependencies. Its value is |
| * made equal to the window size used to generate the trace which is |
| * recorded in the trace header. The dependency graph must be |
| * populated enough such that when a node completes, its potential |
| * child node must be found and the dependency removed before the |
| * completed node itself is removed. Thus as soon as the graph shrinks |
| * to become smaller than this window, we read in the next window. |
| */ |
| const uint32_t windowSize; |
| |
| /** |
| * Hardware resources required to contain in-flight nodes and to |
| * throttle issuing of new nodes when resources are not available. |
| */ |
| HardwareResource hwResource; |
| |
| /** Store the depGraph of GraphNodes */ |
| std::unordered_map<NodeSeqNum, GraphNode*> depGraph; |
| |
| /** |
| * Queue of dependency-free nodes that are pending issue because |
| * resources are not available. This is chosen to be FIFO so that |
| * dependent nodes which become free in program order get pushed |
| * into the queue in that order. Thus nodes are more likely to |
| * issue in program order. |
| */ |
| std::queue<const GraphNode*> depFreeQueue; |
| |
| /** List of nodes that are ready to execute */ |
| std::list<ReadyNode> readyList; |
| |
| protected: |
| // Defining the a stat group |
| struct ElasticDataGenStatGroup : public statistics::Group |
| { |
| /** name is the extension to the name for these stats */ |
| ElasticDataGenStatGroup(statistics::Group *parent, |
| const std::string& _name); |
| /** Stats for data memory accesses replayed. */ |
| statistics::Scalar maxDependents; |
| statistics::Scalar maxReadyListSize; |
| statistics::Scalar numSendAttempted; |
| statistics::Scalar numSendSucceeded; |
| statistics::Scalar numSendFailed; |
| statistics::Scalar numRetrySucceeded; |
| statistics::Scalar numSplitReqs; |
| statistics::Scalar numSOLoads; |
| statistics::Scalar numSOStores; |
| /** Tick when ElasticDataGen completes execution */ |
| statistics::Scalar dataLastTick; |
| } elasticStats; |
| }; |
| |
| /** Instance of FixedRetryGen to replay instruction read requests. */ |
| FixedRetryGen icacheGen; |
| |
| /** Instance of ElasticDataGen to replay data read and write requests. */ |
| ElasticDataGen dcacheGen; |
| |
| /** |
| * This is the control flow that uses the functionality of the icacheGen to |
| * replay the trace. It calls tryNext(). If it returns true then next event |
| * is scheduled at curTick() plus delta. If it returns false then delta is |
| * ignored and control is brought back via recvRetry(). |
| */ |
| void schedIcacheNext(); |
| |
| /** |
| * This is the control flow that uses the functionality of the dcacheGen to |
| * replay the trace. It calls execute(). It checks if execution is complete |
| * and schedules an event to exit simulation accordingly. |
| */ |
| void schedDcacheNext(); |
| |
| /** Event for the control flow method schedIcacheNext() */ |
| EventFunctionWrapper icacheNextEvent; |
| |
| /** Event for the control flow method schedDcacheNext() */ |
| EventFunctionWrapper dcacheNextEvent; |
| |
| /** |
| * This is called when either generator finishes executing from the |
| * trace. |
| */ |
| void checkAndSchedExitEvent(); |
| |
| /** Set to true when one of the generators finishes replaying its trace. */ |
| bool oneTraceComplete; |
| |
| /** |
| * This stores the time offset in the trace, which is taken away from |
| * the ready times of requests. This is specially useful because the time |
| * offset can be very large if the traces are generated from the middle of |
| * a program. |
| */ |
| Tick traceOffset; |
| |
| /** |
| * Number of Trace CPUs in the system used as a shared variable and passed |
| * to the CountedExitEvent event used for counting down exit events. It is |
| * incremented in the constructor call so that the total is arrived at |
| * automatically. |
| */ |
| static int numTraceCPUs; |
| |
| /** |
| * A CountedExitEvent which when serviced decrements the counter. A sim |
| * exit event is scheduled when the counter equals zero, that is all |
| * instances of Trace CPU have had their execCompleteEvent serviced. |
| */ |
| CountedExitEvent *execCompleteEvent; |
| |
| /** |
| * Exit when any one Trace CPU completes its execution. If this is |
| * configured true then the execCompleteEvent is not scheduled. |
| */ |
| const bool enableEarlyExit; |
| |
| /** |
| * Interval of committed instructions specified by the user at which a |
| * progress info message is printed |
| */ |
| const uint64_t progressMsgInterval; |
| |
| /* |
| * The progress msg threshold is kept updated to the next multiple of the |
| * progress msg interval. As soon as the threshold is reached, an info |
| * message is printed. |
| */ |
| uint64_t progressMsgThreshold; |
| struct TraceStats : public statistics::Group |
| { |
| TraceStats(TraceCPU *trace); |
| statistics::Scalar numSchedDcacheEvent; |
| statistics::Scalar numSchedIcacheEvent; |
| |
| /** Stat for number of simulated micro-ops. */ |
| statistics::Scalar numOps; |
| /** Stat for the CPI. This is really cycles per |
| * micro-op and not inst. */ |
| statistics::Formula cpi; |
| } traceStats; |
| |
| public: |
| |
| /** Used to get a reference to the icache port. */ |
| Port &getInstPort() { return icachePort; } |
| |
| /** Used to get a reference to the dcache port. */ |
| Port &getDataPort() { return dcachePort; } |
| |
| }; |
| |
| } // namespace gem5 |
| |
| #endif // __CPU_TRACE_TRACE_CPU_HH__ |
