A packet queue is a class that holds deferred packets and later sends them using the associated CPU-side port or memory-side port. More...

#include <packet_queue.hh>

Inheritance diagram for gem5::PacketQueue:

Classes
class	DeferredPacket
	A deferred packet, buffered to transmit later. More...

Public Member Functions
virtual const std::string	name () const =0
	Provide a name to simplify debugging.

size_t	size () const
	Get the size of the queue.

Tick	deferredPacketReadyTime () const
	Get the next packet ready time.

bool	checkConflict (const PacketPtr pkt, const int blk_size) const
	Check if a packet corresponding to the same address exists in the queue.

bool	trySatisfyFunctional (PacketPtr pkt)
	Check the list of buffered packets against the supplied functional request.

void	schedSendEvent (Tick when)
	Schedule a send event if we are not already waiting for a retry.

void	schedSendTiming (PacketPtr pkt, Tick when)
	Add a packet to the transmit list, and schedule a send event.

void	retry ()
	Retry sending a packet from the queue.

void	disableSanityCheck ()
	This allows a user to explicitly disable the sanity check on the size of the transmitList, which is enabled by default.

DrainState	drain () override
	Draining is the process of clearing out the states of SimObjects.These are the SimObjects that are partially executed or are partially in flight.

Public Member Functions inherited from gem5::Drainable
DrainState	drainState () const
	Return the current drain state of an object.

virtual void	notifyFork ()
	Notify a child process of a fork.

Protected Member Functions
bool	deferredPacketReady () const
	Check whether we have a packet ready to go on the transmit list.

virtual void	sendDeferredPacket ()
	Attempt to send a packet.

virtual bool	sendTiming (PacketPtr pkt)=0
	Send a packet using the appropriate method for the specific subclass (request, response or snoop response).

	PacketQueue (EventManager &_em, const std::string &_label, const std::string &_sendEventName, bool force_order=false, bool disable_sanity_check=false)
	Create a packet queue, linked to an event manager, and a label that will be used for functional print request packets.

virtual	~PacketQueue ()
	Virtual desctructor since the class may be used as a base class.

Protected Member Functions inherited from gem5::Drainable
	Drainable ()

virtual	~Drainable ()

virtual void	drainResume ()
	Resume execution after a successful drain.

void	signalDrainDone () const
	Signal that an object is drained.

Protected Attributes
const std::string	label
	Label to use for print request packets label stack.

bool	waitingOnRetry
	Remember whether we're awaiting a retry.

Private Types
typedef std::list< DeferredPacket >	DeferredPacketList

Private Member Functions
void	processSendEvent ()
	Used to schedule sending of deferred packets.

Private Attributes
DeferredPacketList	transmitList
	A list of outgoing packets.

EventManager &	em
	The manager which is used for the event queue.

EventFunctionWrapper	sendEvent
	Event used to call processSendEvent.

bool	_disableSanityCheck

bool	forceOrder
	if true, inserted packets have to be unconditionally scheduled after the last packet in the queue that references the same address

Detailed Description

A packet queue is a class that holds deferred packets and later sends them using the associated CPU-side port or memory-side port.

Definition at line 65 of file packet_queue.hh.

Member Typedef Documentation

◆ DeferredPacketList

typedef std::list<DeferredPacket> gem5::PacketQueue::DeferredPacketList

private

Definition at line 79 of file packet_queue.hh.

Constructor & Destructor Documentation

◆ PacketQueue()

gem5::PacketQueue::PacketQueue	(	EventManager &	_em,
		const std::string &	_label,
		const std::string &	_sendEventName,
		bool	force_order = false,
		bool	disable_sanity_check = false )

protected

Create a packet queue, linked to an event manager, and a label that will be used for functional print request packets.

Parameters

_em	Event manager used for scheduling this queue
_label	Label to push on the label stack for print request packets
force_order	Force insertion order for packets with same address
disable_sanity_check	Flag used to disable the sanity check on the size of the transmitList. The check is enabled by default.

Definition at line 50 of file packet_queue.cc.

References processSendEvent().

◆ ~PacketQueue()

gem5::PacketQueue::~PacketQueue ( )

protectedvirtual

Virtual desctructor since the class may be used as a base class.

Definition at line 61 of file packet_queue.cc.

Member Function Documentation

◆ checkConflict()

bool gem5::PacketQueue::checkConflict	(	const PacketPtr	pkt,
		const int	blk_size ) const

Check if a packet corresponding to the same address exists in the queue.

Parameters

pkt	The packet to compare against.
blk_size	Block size in bytes.

Returns: Whether a corresponding packet is found.

Definition at line 75 of file packet_queue.cc.

References gem5::MipsISA::p, and transmitList.

Referenced by gem5::BaseCache::CacheReqPacketQueue::checkConflictingSnoop().

◆ deferredPacketReady()

bool gem5::PacketQueue::deferredPacketReady ( ) const

inlineprotected

Check whether we have a packet ready to go on the transmit list.

Definition at line 116 of file packet_queue.hh.

References gem5::curTick(), and transmitList.

Referenced by sendDeferredPacket().

◆ deferredPacketReadyTime()

Tick gem5::PacketQueue::deferredPacketReadyTime ( ) const

inline

Get the next packet ready time.

Definition at line 172 of file packet_queue.hh.

References gem5::MaxTick, and transmitList.

Referenced by gem5::BaseCache::CacheReqPacketQueue::checkConflictingSnoop(), and sendDeferredPacket().

◆ disableSanityCheck()

void gem5::PacketQueue::disableSanityCheck ( )

inline

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.

Definition at line 221 of file packet_queue.hh.

References _disableSanityCheck.

◆ drain()

DrainState gem5::PacketQueue::drain ( )

overridevirtual

Draining is the process of clearing out the states of SimObjects.These are the SimObjects that are partially executed or are partially in flight.

Draining is mostly used before forking and creating a check point.

This function notifies an object that it needs to drain its state.

If the object does not need further simulation to drain internal buffers, it returns DrainState::Drained and automatically switches to the Drained state. If the object needs more simulation, it returns DrainState::Draining and automatically enters the Draining state. Other return values are invalid.

Note: An object that has entered the Drained state can be disturbed by other objects in the system and consequently stop being drained. These perturbations are not visible in the drain state. The simulator therefore repeats the draining process until all objects return DrainState::Drained on the first call to drain().

Returns: DrainState::Drained if the object is drained at this point in time, DrainState::Draining if it needs further simulation.

Implements gem5::Drainable.

Definition at line 228 of file packet_queue.cc.

References DPRINTF, gem5::Drained, gem5::Draining, and transmitList.

◆ name()

virtual const std::string gem5::PacketQueue::name ( ) const

pure virtual

Provide a name to simplify debugging.

Returns: A complete name, appended to module and port

Implemented in gem5::ReqPacketQueue, gem5::RespPacketQueue, and gem5::SnoopRespPacketQueue.

Referenced by retry(), and schedSendTiming().

◆ processSendEvent()

void gem5::PacketQueue::processSendEvent ( )

private

Used to schedule sending of deferred packets.

Definition at line 221 of file packet_queue.cc.

References sendDeferredPacket(), and waitingOnRetry.

Referenced by PacketQueue().

◆ retry()

void gem5::PacketQueue::retry ( )

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.

Definition at line 66 of file packet_queue.cc.

References DPRINTF, name(), sendDeferredPacket(), and waitingOnRetry.

Referenced by gem5::QueuedRequestPort::recvReqRetry(), gem5::QueuedResponsePort::recvRespRetry(), and gem5::QueuedRequestPort::recvRetrySnoopResp().

◆ schedSendEvent()

void gem5::PacketQueue::schedSendEvent ( Tick when )

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.

Parameters

when	time to schedule an event

Definition at line 155 of file packet_queue.cc.

References gem5::curTick(), DPRINTF, gem5::Draining, gem5::Drainable::drainState(), em, gem5::MaxTick, gem5::EventManager::reschedule(), gem5::EventManager::schedule(), gem5::Event::scheduled(), sendEvent, gem5::Drainable::signalDrainDone(), transmitList, waitingOnRetry, and gem5::Event::when().

Referenced by gem5::BaseCache::CacheReqPacketQueue::checkConflictingSnoop(), gem5::BaseCache::CacheRequestPort::schedSendEvent(), schedSendTiming(), and sendDeferredPacket().

◆ schedSendTiming()

void gem5::PacketQueue::schedSendTiming	(	PacketPtr	pkt,
		Tick	when )

Add a packet to the transmit list, and schedule a send event.

Parameters

pkt	Packet to send
when	Absolute time (in ticks) to send packet

Definition at line 107 of file packet_queue.cc.

References _disableSanityCheck, gem5::Packet::cmdString(), gem5::curTick(), DPRINTF, forceOrder, gem5::Packet::getAddr(), gem5::Packet::getSize(), gem5::Packet::isExpressSnoop(), name(), panic, schedSendEvent(), and transmitList.

Referenced by gem5::QueuedRequestPort::schedTimingReq(), gem5::QueuedResponsePort::schedTimingResp(), and gem5::QueuedRequestPort::schedTimingSnoopResp().

◆ sendDeferredPacket()

void gem5::PacketQueue::sendDeferredPacket ( )

protectedvirtual

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).

Reimplemented in gem5::BaseCache::CacheReqPacketQueue.

Definition at line 191 of file packet_queue.cc.

References deferredPacketReady(), deferredPacketReadyTime(), gem5::ArmISA::dp, schedSendEvent(), sendTiming(), transmitList, and waitingOnRetry.

Referenced by processSendEvent(), and retry().