mem: Add a QoS-aware Memory Controller type

This is the implementation of QoS algorithms support for gem5 memory
objects. This change-list provides a framework for specifying QoS
algorithm which can be used to prioritise service to specific masters in
the memory controller.
The QoS support implemented here is designed to be extendable so that
new QoS algorithms can be easily plugged into the memory controller as
"QoS Policies".

Change-Id: I0b611f13fce54dd1dd444eb806f8e98afd248bd5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11970
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/src/mem/qos/policy.hh b/src/mem/qos/policy.hh
new file mode 100644
index 000000000..3ffe4811d
--- /dev/null
+++ b/src/mem/qos/policy.hh
@@ -0,0 +1,131 @@
+/*
+ * 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_POLICY_HH__
+#define __MEM_QOS_POLICY_HH__
+
+#include "base/trace.hh"
+#include "debug/QOS.hh"
+#include "mem/qos/mem_ctrl.hh"
+#include "mem/packet.hh"
+#include "sim/system.hh"
+
+namespace QoS {
+
+/**
+ * QoS Policy base class
+ *
+ * QoS Policy base class: all QoS policies derive from this class to
+ * implement specific QoS scheduling algorithms
+ *
+ */
+class Policy : public SimObject
+{
+  public:
+    using Params = QoSPolicyParams;
+    Policy(const Params* p);
+
+    virtual ~Policy();
+
+    virtual void regStats() override {};
+
+    virtual void init() override {};
+
+    /**
+     * Setting a pointer to the Memory Controller implementing
+     * the policy.
+     */
+    void setMemCtrl(MemCtrl* mem) { memCtrl = mem; };
+
+    /**
+     * Builds a MasterID/value pair given a master input.
+     * This will be lookuped in the system list of masters in order
+     * to retrieve the associated MasterID.
+     * In case the master name/object cannot be resolved, the pairing
+     * method will panic.
+     *
+     * @param master Master to lookup in the system
+     * @param value Value to be associated with the MasterID
+     * @return A MasterID/Value pair.
+     */
+    template <typename M, typename T>
+    std::pair<MasterID, T> pair(M master, T value);
+
+    /**
+     * Schedules data - must be defined by derived class
+     *
+     * @param mId master id to schedule
+     * @param data data to schedule
+     * @return QoS priority value
+     */
+    virtual uint8_t schedule(const MasterID mId, const uint64_t data) = 0;
+
+    /**
+     * Schedules a packet. Non virtual interface for the scheduling
+     * method requiring a master ID.
+     *
+     * @param pkt pointer to packet to schedule
+     * @return QoS priority value
+     */
+    uint8_t schedule(const PacketPtr pkt);
+
+  protected:
+    /** Pointer to parent memory controller implementing the policy */
+    MemCtrl* memCtrl;
+};
+
+template <typename M, typename T>
+std::pair<MasterID, T>
+Policy::pair(M master, T value)
+{
+    auto id = memCtrl->system()->lookupMasterId(master);
+
+    panic_if(id == Request::invldMasterId,
+             "Unable to find master %s\n", master);
+
+    DPRINTF(QOS,
+            "Master %s [id %d] associated with QoS data %d\n",
+            master, id, value);
+
+    return std::pair<MasterID, T>(id, value);
+}
+
+} // namespace QoS
+
+#endif /* __MEM_QOS_POLICY_HH__ */