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Diffstat (limited to 'src/mem/qos/q_policy.hh')
| -rw-r--r-- | src/mem/qos/q_policy.hh | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/src/mem/qos/q_policy.hh b/src/mem/qos/q_policy.hh new file mode 100644 index 000000000..3e455e89c --- /dev/null +++ b/src/mem/qos/q_policy.hh @@ -0,0 +1,188 @@ +/* + * 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_Q_POLICY_HH__ +#define __MEM_QOS_Q_POLICY_HH__ + +#include <deque> +#include <unordered_set> + +#include "mem/packet.hh" +#include "params/QoSMemCtrl.hh" + +namespace QoS { + +class MemCtrl; + +/** + * QoS Queue Policy + * + * The QoS Queue Policy class implements algorithms to schedule packets + * within the same QoS priority queue + */ +class QueuePolicy +{ + public: + typedef std::deque<PacketPtr> PacketQueue; + + /** + * This factory method is used for generating the queue policy. It takes + * the memory controller params as an argument and returns the related + * QueuePolicy object. If no particular QueuePolicy has been specified in + * the QoSMemCtrlParams, the method will default to a LIFO queue policy. + * + * @param p QoS::MemCtrl parameter variable + * @return Pointer to the QueuePolicy + */ + static QueuePolicy* create(const QoSMemCtrlParams* p); + + /** + * This method is called by the memory controller after it enqueues a + * packet. It is a way for the queue policy to hook into the packet + * enqueuing and update relevant metadata. This will then be used once + * the QueuePolicy::selectPacket will be called. + * + * @param pkt Enqueued packet + */ + virtual void enqueuePacket(PacketPtr pkt) {}; + + /** + * Policy selector. + * The implementation of this virtual method selects the packet + * to be serviced from the packet queue passed as an argument. + * + * @param queue Packet queue + * @return Iterator pointing to the packet in the queue to be + * serviced + */ + virtual PacketQueue::iterator selectPacket(PacketQueue* queue) = 0; + + /** + * Setting a pointer to the Memory Controller implementing + * the policy. + */ + void setMemCtrl(MemCtrl* mem) { memCtrl = mem; }; + + protected: + QueuePolicy(const QoSMemCtrlParams* p) + : memCtrl(nullptr) + {} + + /** Pointer to parent memory controller implementing the policy */ + MemCtrl* memCtrl; +}; + +/** Last In First Out Queue Policy */ +class LifoQueuePolicy : public QueuePolicy +{ + public: + LifoQueuePolicy(const QoSMemCtrlParams* p) + : QueuePolicy(p) + {} + + /** + * Implements LIFO packet select policy + * + * @param queue The queue in which to select a packet + * @return Iterator to the selected packet + */ + PacketQueue::iterator + selectPacket(PacketQueue* queue) override + { + return queue->end(); + } +}; + +/** First In First Out Queue Policy */ +class FifoQueuePolicy : public QueuePolicy +{ + public: + FifoQueuePolicy(const QoSMemCtrlParams* p) + : QueuePolicy(p) + {} + + /** + * Implements FCFS packet select policy + * + * @param queue The queue in which to select a packet + * @return Iterator to the selected packet + */ + PacketQueue::iterator + selectPacket(PacketQueue* queue) override + { + return queue->begin(); + } +}; + +/** + * Least Recently Granted Queue Policy + * It selects packets from the queue with a round + * robin-like policy: using the master id as a switching + * parameter rather than switching over a time quantum. + */ +class LrgQueuePolicy : public QueuePolicy +{ + public: + LrgQueuePolicy(const QoSMemCtrlParams* p) + : QueuePolicy(p) + {} + + void enqueuePacket(PacketPtr pkt) override; + + /** + * Implements LRG packet select policy + * + * @param queue The queue in which to select a packet + * @return Iterator to the selected packet + */ + PacketQueue::iterator + selectPacket(PacketQueue* queue) override; + + protected: + /** + * Support structure for lrg algorithms: + * keeps track of serviced masters, + * always serve the front element. + */ + std::list<MasterID> toServe; +}; + +} // namespace QoS + +#endif /* __MEM_QOS_Q_POLICY_HH__ */ |