mem: Add a simple QoS-aware Memory Controller

This patch implements QoSMemorySink: a simple generic QoS-aware memory
controller which inherits from QoS::MemCtrl.

Change-Id: I537a4e2d4cb8f54fa0002eb088b2c6957afb9973
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11971
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Matthew Poremba <porembam@gmail.com>

1 files changed, 248 insertions, 0 deletions

diff --git a/src/mem/qos/mem_sink.hh b/src/mem/qos/mem_sink.hh
new file mode 100644
index 000000000..84258e0ac
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+++ b/src/mem/qos/mem_sink.hh
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+/*
+ * Copyright (c) 2018 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.
+ *
+ * Author: Matteo Andreozzi
+ */
+
+
+#ifndef __MEM_QOS_MEM_SINK_HH__
+#define __MEM_QOS_MEM_SINK_HH__
+
+#include "mem/qos/mem_ctrl.hh"
+#include "mem/qport.hh"
+#include "params/QoSMemSinkCtrl.hh"
+
+namespace QoS {
+
+/**
+ * QoS Memory Sink
+ *
+ * The QoS Memory Sink is a lightweight memory controller with QoS
+ * support. It is meant to provide a QoS aware simple memory system
+ * without the need of using a complex DRAM memory controller
+ */
+class MemSinkCtrl : public MemCtrl
+{
+  protected:
+    /**
+     * The Request packets are store in a multiple dequeue structure,
+     * based on their QoS priority
+     */
+    using PacketQueue = std::deque<PacketPtr>;
+
+  private:
+    class MemoryPort : public QueuedSlavePort
+    {
+      private:
+        /** reference to parent memory object */
+        MemSinkCtrl& memory;
+
+        /** Outgoing packet responses queue */
+        RespPacketQueue queue;
+
+      public:
+       /**
+        * Constructor
+        *
+        * @param n port name
+        * @param m reference to ProfileGen parent object
+        */
+        MemoryPort(const std::string&, MemSinkCtrl&);
+
+      protected:
+       /**
+        * Receive a Packet in Atomic mode
+        *
+        * @param pkt pointer to memory packet
+        * @return packet access latency in ticks
+        */
+        Tick recvAtomic(PacketPtr pkt);
+
+        /**
+        * Receive a Packet in Functional mode
+        *
+        * @param pkt pointer to memory packet
+        */
+        void recvFunctional(PacketPtr pkt);
+
+        /**
+        * Receive a Packet in Timing mode
+        *
+        * @param pkt pointer to memory packet
+        * @return true if the request was accepted
+        */
+        bool recvTimingReq(PacketPtr pkt);
+
+        /**
+         * Gets the configured address ranges for this port
+         * @return the configured address ranges for this port
+         */
+        AddrRangeList getAddrRanges() const;
+
+    };
+
+  public:
+    /**
+     * QoS Memory Sink Constructor
+     *
+     * @param p QoS Memory Sink configuration parameters
+     */
+    MemSinkCtrl(const QoSMemSinkCtrlParams*);
+
+    virtual ~MemSinkCtrl();
+
+    /**
+     * Checks and return the Drain state of this SimObject
+     * @return current Drain state
+     */
+    DrainState drain() override;
+
+    /**
+     * Getter method to access this memory's slave port
+     *
+     * @param interface interface name
+     * @param idx port ID number
+     * @return reference to this memory's slave port
+     */
+    BaseSlavePort& getSlavePort(const std::string&,
+            PortID = InvalidPortID) override;
+
+    /**
+     * Initializes this object
+     */
+    void init() override;
+
+  protected:
+    /** Memory between requests latency (ticks) */
+    const Tick requestLatency;
+
+    /** Memory response latency (ticks) */
+    const Tick responseLatency;
+
+    /** Memory packet size in bytes */
+    const uint64_t memoryPacketSize;
+
+    /** Read request packets queue buffer size in #packets */
+    const uint64_t readBufferSize;
+
+    /** Write request packets queue buffer size in #packets */
+    const uint64_t writeBufferSize;
+
+    /** Memory slave port */
+    MemoryPort port;
+
+    /** Read request pending */
+    bool retryRdReq;
+
+    /** Write request pending */
+    bool retryWrReq;
+
+    /** Next request service time */
+    Tick nextRequest;
+
+    /** Count the number of read retries */
+    Stats::Scalar numReadRetries;
+
+    /** Count the number of write retries */
+    Stats::Scalar numWriteRetries;
+
+    /**
+     * QoS-aware (per priority) incoming read requests packets queue
+     */
+    std::vector<PacketQueue> readQueue;
+
+    /**
+     * QoS-aware (per priority) incoming read requests packets queue
+     */
+    std::vector<PacketQueue> writeQueue;
+
+    /**
+     * Processes the next Request event according to configured
+     * request latency
+     */
+    void processNextReqEvent();
+
+    /** Event wrapper to schedule next request handler function */
+    EventWrapper<
+        MemSinkCtrl,
+        &MemSinkCtrl::processNextReqEvent> nextReqEvent;
+
+    /**
+     * Check if the read queue has room for more entries
+     *
+     * @param packets The number of entries needed in the read queue
+     * @return true if read queue is full, false otherwise
+     */
+    inline bool readQueueFull(const uint64_t packets) const;
+
+    /**
+     * Check if the write queue has room for more entries
+     *
+     * @param packets  The number of entries needed in the write queue
+     * @return true if write queue is full, false otherwise
+     */
+    inline bool writeQueueFull(const uint64_t packets) const;
+
+    /**
+     * Receive a Packet in Atomic mode
+     *
+     * @param pkt pointer to memory packet
+     * @return packet access latency in ticks
+     */
+    Tick recvAtomic(PacketPtr pkt);
+
+    /**
+     * Receive a Packet in Functional mode
+     *
+     * @param pkt pointer to memory packet
+     */
+    void recvFunctional(PacketPtr pkt);
+
+   /**
+    * Receive a Packet in Timing mode
+    *
+    * @param pkt pointer to memory packet
+    * @return true if the request was accepted
+    */
+    bool recvTimingReq(PacketPtr pkt);
+
+    /** Registers statistics */
+    void regStats() override;
+};
+
+} // namespace QoS
+
+#endif /* __MEM_QOS_MEM_SINK_HH__ */