mem: hmc: serial link model

This changeset adds a serial link model for the Hybrid Memory Cube (HMC).
SerialLink is a simple variation of the Bridge class, with the ability to
account for the latency of packet serialization. Also trySendTiming has been
modified to correctly model bandwidth.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>

1 files changed, 329 insertions, 0 deletions

diff --git a/src/mem/serial_link.hh b/src/mem/serial_link.hh
new file mode 100644
index 000000000..d4f6ca488
--- /dev/null
+++ b/src/mem/serial_link.hh
@@ -0,0 +1,329 @@
+/*
+ * Copyright (c) 2011-2013 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) 2006 The Regents of The University of Michigan
+ * Copyright (c) 2015 The University of Bologna
+ * 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: Ali Saidi
+ *          Steve Reinhardt
+ *          Andreas Hansson
+ *          Erfan Azarkhish
+ */
+
+/**
+ * @file
+ * Declaration of the SerialLink Class, modeling Hybrid-Memory-Cube's serial
+ * interface.
+ */
+
+#ifndef __MEM_SERIAL_LINK_HH__
+#define __MEM_SERIAL_LINK_HH__
+
+#include <deque>
+
+#include "base/types.hh"
+#include "mem/mem_object.hh"
+#include "params/SerialLink.hh"
+
+/**
+ * SerialLink is a simple variation of the Bridge class, with the ability to
+ * account for the latency of packet serialization. We assume that the
+ * serializer component at the transmitter side does not need to receive the
+ * whole packet to start the serialization. But the deserializer waits for the
+ * complete packet to check its integrity first.
+  */
+class SerialLink : public MemObject
+{
+  protected:
+
+    /**
+     * A deferred packet stores a packet along with its scheduled
+     * transmission time
+     */
+    class DeferredPacket
+    {
+
+      public:
+
+        const Tick tick;
+        const PacketPtr pkt;
+
+        DeferredPacket(PacketPtr _pkt, Tick _tick) : tick(_tick), pkt(_pkt)
+        { }
+    };
+
+    // Forward declaration to allow the slave port to have a pointer
+    class SerialLinkMasterPort;
+
+    /**
+     * The port on the side that receives requests and sends
+     * responses. The slave port has a set of address ranges that it
+     * is responsible for. The slave port also has a buffer for the
+     * responses not yet sent.
+     */
+    class SerialLinkSlavePort : public SlavePort
+    {
+
+      private:
+
+        /** The serial_link to which this port belongs. */
+        SerialLink& serial_link;
+
+        /**
+         * Master port on the other side of the serial_link.
+         */
+        SerialLinkMasterPort& masterPort;
+
+        /** Minimum request delay though this serial_link. */
+        const Cycles delay;
+
+        /** Address ranges to pass through the serial_link */
+        const AddrRangeList ranges;
+
+        /**
+         * Response packet queue. Response packets are held in this
+         * queue for a specified delay to model the processing delay
+         * of the serial_link. We use a deque as we need to iterate over
+         * the items for functional accesses.
+         */
+        std::deque<DeferredPacket> transmitList;
+
+        /** Counter to track the outstanding responses. */
+        unsigned int outstandingResponses;
+
+        /** If we should send a retry when space becomes available. */
+        bool retryReq;
+
+        /** Max queue size for reserved responses. */
+        unsigned int respQueueLimit;
+
+        /**
+         * Is this side blocked from accepting new response packets.
+         *
+         * @return true if the reserved space has reached the set limit
+         */
+        bool respQueueFull() const;
+
+        /**
+         * Handle send event, scheduled when the packet at the head of
+         * the response queue is ready to transmit (for timing
+         * accesses only).
+         */
+        void trySendTiming();
+
+        /** Send event for the response queue. */
+        EventWrapper<SerialLinkSlavePort,
+                     &SerialLinkSlavePort::trySendTiming> sendEvent;
+
+      public:
+
+        /**
+         * Constructor for the SerialLinkSlavePort.
+         *
+         * @param _name the port name including the owner
+         * @param _serial_link the structural owner
+         * @param _masterPort the master port on the other side of the
+         * serial_link
+         * @param _delay the delay in cycles from receiving to sending
+         * @param _resp_limit the size of the response queue
+         * @param _ranges a number of address ranges to forward
+         */
+        SerialLinkSlavePort(const std::string& _name, SerialLink&
+                        _serial_link, SerialLinkMasterPort& _masterPort,
+                        Cycles _delay, int _resp_limit, const
+                        std::vector<AddrRange>& _ranges);
+
+        /**
+         * Queue a response packet to be sent out later and also schedule
+         * a send if necessary.
+         *
+         * @param pkt a response to send out after a delay
+         * @param when tick when response packet should be sent
+         */
+        void schedTimingResp(PacketPtr pkt, Tick when);
+
+        /**
+         * Retry any stalled request that we have failed to accept at
+         * an earlier point in time. This call will do nothing if no
+         * request is waiting.
+         */
+        void retryStalledReq();
+
+      protected:
+
+        /** When receiving a timing request from the peer port,
+            pass it to the serial_link. */
+        bool recvTimingReq(PacketPtr pkt);
+
+        /** When receiving a retry request from the peer port,
+            pass it to the serial_link. */
+        void recvRespRetry();
+
+        /** When receiving a Atomic requestfrom the peer port,
+            pass it to the serial_link. */
+        Tick recvAtomic(PacketPtr pkt);
+
+        /** When receiving a Functional request from the peer port,
+            pass it to the serial_link. */
+        void recvFunctional(PacketPtr pkt);
+
+        /** When receiving a address range request the peer port,
+            pass it to the serial_link. */
+        AddrRangeList getAddrRanges() const;
+    };
+
+
+    /**
+     * Port on the side that forwards requests and receives
+     * responses. The master port has a buffer for the requests not
+     * yet sent.
+     */
+    class SerialLinkMasterPort : public MasterPort
+    {
+
+      private:
+
+        /** The serial_link to which this port belongs. */
+        SerialLink& serial_link;
+
+        /**
+         * The slave port on the other side of the serial_link.
+         */
+        SerialLinkSlavePort& slavePort;
+
+        /** Minimum delay though this serial_link. */
+        const Cycles delay;
+
+        /**
+         * Request packet queue. Request packets are held in this
+         * queue for a specified delay to model the processing delay
+         * of the serial_link.  We use a deque as we need to iterate over
+         * the items for functional accesses.
+         */
+        std::deque<DeferredPacket> transmitList;
+
+        /** Max queue size for request packets */
+        const unsigned int reqQueueLimit;
+
+        /**
+         * Handle send event, scheduled when the packet at the head of
+         * the outbound queue is ready to transmit (for timing
+         * accesses only).
+         */
+        void trySendTiming();
+
+        /** Send event for the request queue. */
+        EventWrapper<SerialLinkMasterPort,
+                     &SerialLinkMasterPort::trySendTiming> sendEvent;
+
+      public:
+
+        /**
+         * Constructor for the SerialLinkMasterPort.
+         *
+         * @param _name the port name including the owner
+         * @param _serial_link the structural owner
+         * @param _slavePort the slave port on the other side of the
+         * serial_link
+         * @param _delay the delay in cycles from receiving to sending
+         * @param _req_limit the size of the request queue
+         */
+        SerialLinkMasterPort(const std::string& _name, SerialLink&
+                         _serial_link, SerialLinkSlavePort& _slavePort, Cycles
+                         _delay, int _req_limit);
+
+        /**
+         * Is this side blocked from accepting new request packets.
+         *
+         * @return true if the occupied space has reached the set limit
+         */
+        bool reqQueueFull() const;
+
+        /**
+         * Queue a request packet to be sent out later and also schedule
+         * a send if necessary.
+         *
+         * @param pkt a request to send out after a delay
+         * @param when tick when response packet should be sent
+         */
+        void schedTimingReq(PacketPtr pkt, Tick when);
+
+        /**
+         * Check a functional request against the packets in our
+         * request queue.
+         *
+         * @param pkt packet to check against
+         *
+         * @return true if we find a match
+         */
+        bool checkFunctional(PacketPtr pkt);
+
+      protected:
+
+        /** When receiving a timing request from the peer port,
+            pass it to the serial_link. */
+        bool recvTimingResp(PacketPtr pkt);
+
+        /** When receiving a retry request from the peer port,
+            pass it to the serial_link. */
+        void recvReqRetry();
+    };
+
+    /** Slave port of the serial_link. */
+    SerialLinkSlavePort slavePort;
+
+    /** Master port of the serial_link. */
+    SerialLinkMasterPort masterPort;
+
+    /** Number of parallel lanes in this serial link */
+    unsigned num_lanes;
+
+  public:
+
+    virtual BaseMasterPort& getMasterPort(const std::string& if_name,
+                                          PortID idx = InvalidPortID);
+    virtual BaseSlavePort& getSlavePort(const std::string& if_name,
+                                        PortID idx = InvalidPortID);
+
+    virtual void init();
+
+    typedef SerialLinkParams Params;
+
+    SerialLink(SerialLinkParams *p);
+};
+
+#endif //__MEM_SERIAL_LINK_HH__