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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_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__ */
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