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/*
* Copyright (c) 2012,2015,2018 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.
*
* Copyright (c) 2006 The Regents of The University of Michigan
* 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;
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* 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
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#ifndef __MEM_PACKET_QUEUE_HH__
#define __MEM_PACKET_QUEUE_HH__
/**
* @file
* Declaration of a simple PacketQueue that is associated with
* a port on which it attempts to send packets according to the time
* stamp given to them at insertion. The packet queue is responsible
* for the flow control of the port.
*/
#include <list>
#include "mem/port.hh"
#include "sim/drain.hh"
#include "sim/eventq.hh"
namespace gem5
{
/**
* A packet queue is a class that holds deferred packets and later
* sends them using the associated CPU-side port or memory-side port.
*/
class PacketQueue : public Drainable
{
private:
/** A deferred packet, buffered to transmit later. */
class DeferredPacket
{
public:
Tick tick; ///< The tick when the packet is ready to transmit
PacketPtr pkt; ///< Pointer to the packet to transmit
DeferredPacket(Tick t, PacketPtr p)
: tick(t), pkt(p)
{}
};
typedef std::list<DeferredPacket> DeferredPacketList;
/** A list of outgoing packets. */
DeferredPacketList transmitList;
/** The manager which is used for the event queue */
EventManager& em;
/** Used to schedule sending of deferred packets. */
void processSendEvent();
/** Event used to call processSendEvent. */
EventFunctionWrapper sendEvent;
/*
* Optionally disable the sanity check
* on the size of the transmitList. The
* sanity check will be enabled by default.
*/
bool _disableSanityCheck;
/**
* if true, inserted packets have to be unconditionally scheduled
* after the last packet in the queue that references the same
* address
*/
bool forceOrder;
protected:
/** Label to use for print request packets label stack. */
const std::string label;
/** Remember whether we're awaiting a retry. */
bool waitingOnRetry;
/** Check whether we have a packet ready to go on the transmit list. */
bool deferredPacketReady() const
{ return !transmitList.empty() && transmitList.front().tick <= curTick(); }
/**
* Attempt to send a packet. Note that a subclass of the
* PacketQueue can override this method and thus change the
* behaviour (as done by the cache for the request queue). The
* default implementation sends the head of the transmit list. The
* caller must guarantee that the list is non-empty and that the
* head packet is scheduled for curTick() (or earlier).
*/
virtual void sendDeferredPacket();
/**
* Send a packet using the appropriate method for the specific
* subclass (request, response or snoop response).
*/
virtual bool sendTiming(PacketPtr pkt) = 0;
/**
* Create a packet queue, linked to an event manager, and a label
* that will be used for functional print request packets.
*
* @param _em Event manager used for scheduling this queue
* @param _label Label to push on the label stack for print request packets
* @param force_order Force insertion order for packets with same address
* @param disable_sanity_check Flag used to disable the sanity check
* on the size of the transmitList. The check is enabled by default.
*/
PacketQueue(EventManager& _em, const std::string& _label,
const std::string& _sendEventName,
bool force_order = false,
bool disable_sanity_check = false);
/**
* Virtual desctructor since the class may be used as a base class.
*/
virtual ~PacketQueue();
public:
/**
* Provide a name to simplify debugging.
*
* @return A complete name, appended to module and port
*/
virtual const std::string name() const = 0;
/**
* Get the size of the queue.
*/
size_t size() const { return transmitList.size(); }
/**
* Get the next packet ready time.
*/
Tick deferredPacketReadyTime() const
{ return transmitList.empty() ? MaxTick : transmitList.front().tick; }
/**
* Check if a packet corresponding to the same address exists in the
* queue.
*
* @param pkt The packet to compare against.
* @param blk_size Block size in bytes.
* @return Whether a corresponding packet is found.
*/
bool checkConflict(const PacketPtr pkt, const int blk_size) const;
/** Check the list of buffered packets against the supplied
* functional request. */
bool trySatisfyFunctional(PacketPtr pkt);
/**
* Schedule a send event if we are not already waiting for a
* retry. If the requested time is before an already scheduled
* send event, the event will be rescheduled. If MaxTick is
* passed, no event is scheduled. Instead, if we are idle and
* asked to drain then check and signal drained.
*
* @param when time to schedule an event
*/
void schedSendEvent(Tick when);
/**
* Add a packet to the transmit list, and schedule a send event.
*
* @param pkt Packet to send
* @param when Absolute time (in ticks) to send packet
*/
void schedSendTiming(PacketPtr pkt, Tick when);
/**
* Retry sending a packet from the queue. Note that this is not
* necessarily the same packet if something has been added with an
* earlier time stamp.
*/
void retry();
/**
* This allows a user to explicitly disable the sanity check
* on the size of the transmitList, which is enabled by default.
* Users must use this function to explicitly disable the sanity
* check.
*/
void disableSanityCheck() { _disableSanityCheck = true; }
DrainState drain() override;
};
class ReqPacketQueue : public PacketQueue
{
protected:
RequestPort& memSidePort;
// Static definition so it can be called when constructing the parent
// without us being completely initialized.
static const std::string name(const RequestPort& memSidePort,
const std::string& label)
{ return memSidePort.name() + "-" + label; }
public:
/**
* Create a request packet queue, linked to an event manager, a
* memory-side port, and a label that will be used for functional print
* request packets.
*
* @param _em Event manager used for scheduling this queue
* @param _mem_side_port Mem_side port used to send the packets
* @param _label Label to push on the label stack for print request packets
*/
ReqPacketQueue(EventManager& _em, RequestPort& _mem_side_port,
const std::string _label = "ReqPacketQueue");
virtual ~ReqPacketQueue() { }
const std::string name() const
{ return name(memSidePort, label); }
bool sendTiming(PacketPtr pkt);
};
class SnoopRespPacketQueue : public PacketQueue
{
protected:
RequestPort& memSidePort;
// Static definition so it can be called when constructing the parent
// without us being completely initialized.
static const std::string name(const RequestPort& memSidePort,
const std::string& label)
{ return memSidePort.name() + "-" + label; }
public:
/**
* Create a snoop response packet queue, linked to an event
* manager, a memory-side port, and a label that will be used for
* functional print request packets.
*
* @param _em Event manager used for scheduling this queue
* @param _mem_side_port memory-side port used to send the packets
* @param force_order Force insertion order for packets with same address
* @param _label Label to push on the label stack for print request packets
*/
SnoopRespPacketQueue(EventManager& _em, RequestPort& _mem_side_port,
bool force_order = false,
const std::string _label = "SnoopRespPacketQueue");
virtual ~SnoopRespPacketQueue() { }
const std::string name() const
{ return name(memSidePort, label); }
bool sendTiming(PacketPtr pkt);
};
class RespPacketQueue : public PacketQueue
{
protected:
ResponsePort& cpuSidePort;
// Static definition so it can be called when constructing the parent
// without us being completely initialized.
static const std::string name(const ResponsePort& cpuSidePort,
const std::string& label)
{ return cpuSidePort.name() + "-" + label; }
public:
/**
* Create a response packet queue, linked to an event manager, a
* CPU-side port, and a label that will be used for functional print
* request packets.
*
* @param _em Event manager used for scheduling this queue
* @param _cpu_side_port Cpu_side port used to send the packets
* @param force_order Force insertion order for packets with same address
* @param _label Label to push on the label stack for print request packets
*/
RespPacketQueue(EventManager& _em, ResponsePort& _cpu_side_port,
bool force_order = false,
const std::string _label = "RespPacketQueue");
virtual ~RespPacketQueue() { }
const std::string name() const
{ return name(cpuSidePort, label); }
bool sendTiming(PacketPtr pkt);
};
} // namespace gem5
#endif // __MEM_PACKET_QUEUE_HH__