The simple memory is a basic single-ported memory controller with a configurable throughput and latency. More...

#include <simple_mem.hh>

Inheritance diagram for SimpleMemory:

Classes
class	DeferredPacket
	A deferred packet stores a packet along with its scheduled transmission time. More...

class	MemoryPort

Public Member Functions
	SimpleMemory (const SimpleMemoryParams *p)

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. More...

Port &	getPort (const std::string &if_name, PortID idx=InvalidPortID) override
	Get a port with a given name and index. More...

void	init () override
	init() is called after all C++ SimObjects have been created and all ports are connected. More...

Public Member Functions inherited from AbstractMemory
	AbstractMemory (const Params *p)

virtual	~AbstractMemory ()

void	initState () override
	initState() is called on each SimObject when not restoring from a checkpoint. More...

bool	isNull () const
	See if this is a null memory that should never store data and always return zero. More...

void	setBackingStore (uint8_t *pmem_addr)
	Set the host memory backing store to be used by this memory controller. More...

const std::list< LockedAddr > &	getLockedAddrList () const
	Get the list of locked addresses to allow checkpointing. More...

void	addLockedAddr (LockedAddr addr)
	Add a locked address to allow for checkpointing. More...

System *	system () const
	read the system pointer Implemented for completeness with the setter More...

void	system (System *sys)
	Set the system pointer on this memory This can't be done via a python parameter because the system needs pointers to all the memories and the reverse would create a cycle in the object graph. More...

const Params *	params () const

AddrRange	getAddrRange () const
	Get the address range. More...

uint8_t *	toHostAddr (Addr addr) const
	Transform a gem5 address space address into its physical counterpart in the host address space. More...

uint64_t	size () const
	Get the memory size. More...

Addr	start () const
	Get the start address. More...

bool	isConfReported () const
	Should this memory be passed to the kernel and part of the OS physical memory layout. More...

bool	isInAddrMap () const
	Some memories are used as shadow memories or should for other reasons not be part of the global address map. More...

bool	isKvmMap () const
	When shadow memories are in use, KVM may want to make one or the other, but cannot map both into the guest address space. More...

void	access (PacketPtr pkt)
	Perform an untimed memory access and update all the state (e.g. More...

void	functionalAccess (PacketPtr pkt)
	Perform an untimed memory read or write without changing anything but the memory itself. More...

Public Member Functions inherited from ClockedObject
	ClockedObject (const ClockedObjectParams *p)

const Params *	params () const

void	serialize (CheckpointOut &cp) const override
	Serialize an object. More...

void	unserialize (CheckpointIn &cp) override
	Unserialize an object. More...

Public Member Functions inherited from SimObject
const Params *	params () const

	SimObject (const Params *_params)

virtual	~SimObject ()

virtual const std::string	name () const

virtual void	loadState (CheckpointIn &cp)
	loadState() is called on each SimObject when restoring from a checkpoint. More...

virtual void	regProbePoints ()
	Register probe points for this object. More...

virtual void	regProbeListeners ()
	Register probe listeners for this object. More...

ProbeManager *	getProbeManager ()
	Get the probe manager for this object. More...

virtual void	startup ()
	startup() is the final initialization call before simulation. More...

DrainState	drain () override
	Provide a default implementation of the drain interface for objects that don't need draining. More...

virtual void	memWriteback ()
	Write back dirty buffers to memory using functional writes. More...

virtual void	memInvalidate ()
	Invalidate the contents of memory buffers. More...

void	serialize (CheckpointOut &cp) const override
	Serialize an object. More...

void	unserialize (CheckpointIn &cp) override
	Unserialize an object. More...

Public Member Functions inherited from EventManager
EventQueue *	eventQueue () const

void	schedule (Event &event, Tick when)

void	deschedule (Event &event)

void	reschedule (Event &event, Tick when, bool always=false)

void	schedule (Event *event, Tick when)

void	deschedule (Event *event)

void	reschedule (Event *event, Tick when, bool always=false)

void	wakeupEventQueue (Tick when=(Tick) -1)
	This function is not needed by the usual gem5 event loop but may be necessary in derived EventQueues which host gem5 on other schedulers. More...

void	setCurTick (Tick newVal)

	EventManager (EventManager &em)
	Event manger manages events in the event queue. More...

	EventManager (EventManager *em)

	EventManager (EventQueue *eq)

Public Member Functions inherited from Serializable
	Serializable ()

virtual	~Serializable ()

void	serializeSection (CheckpointOut &cp, const char *name) const
	Serialize an object into a new section. More...

void	serializeSection (CheckpointOut &cp, const std::string &name) const

void	unserializeSection (CheckpointIn &cp, const char *name)
	Unserialize an a child object. More...

void	unserializeSection (CheckpointIn &cp, const std::string &name)

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

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

Public Member Functions inherited from Stats::Group
	Group (Group parent, const char name=nullptr)
	Construct a new statistics group. More...

virtual	~Group ()

virtual void	regStats ()
	Callback to set stat parameters. More...

virtual void	resetStats ()
	Callback to reset stats. More...

virtual void	preDumpStats ()
	Callback before stats are dumped. More...

void	addStat (Stats::Info *info)
	Register a stat with this group. More...

const std::map< std::string, Group * > &	getStatGroups () const
	Get all child groups associated with this object. More...

const std::vector< Info * > &	getStats () const
	Get all stats associated with this object. More...

void	addStatGroup (const char name, Group block)
	Add a stat block as a child of this block. More...

const Info *	resolveStat (std::string name) const
	Resolve a stat by its name within this group. More...

	Group ()=delete

	Group (const Group &)=delete

Group &	operator= (const Group &)=delete

Public Member Functions inherited from Clocked
void	updateClockPeriod ()
	Update the tick to the current tick. More...

Tick	clockEdge (Cycles cycles=Cycles(0)) const
	Determine the tick when a cycle begins, by default the current one, but the argument also enables the caller to determine a future cycle. More...

Cycles	curCycle () const
	Determine the current cycle, corresponding to a tick aligned to a clock edge. More...

Tick	nextCycle () const
	Based on the clock of the object, determine the start tick of the first cycle that is at least one cycle in the future. More...

uint64_t	frequency () const

Tick	clockPeriod () const

double	voltage () const

Cycles	ticksToCycles (Tick t) const

Tick	cyclesToTicks (Cycles c) const

Protected Member Functions
Tick	recvAtomic (PacketPtr pkt)

Tick	recvAtomicBackdoor (PacketPtr pkt, MemBackdoorPtr &_backdoor)

void	recvFunctional (PacketPtr pkt)

bool	recvTimingReq (PacketPtr pkt)

void	recvRespRetry ()

Protected Member Functions inherited from AbstractMemory
bool	checkLockedAddrList (PacketPtr pkt)

void	trackLoadLocked (PacketPtr pkt)

bool	writeOK (PacketPtr pkt)

Protected Member Functions inherited from Drainable
	Drainable ()

virtual	~Drainable ()

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

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

Protected Member Functions inherited from Clocked
	Clocked (ClockDomain &clk_domain)
	Create a clocked object and set the clock domain based on the parameters. More...

	Clocked (Clocked &)=delete

Clocked &	operator= (Clocked &)=delete

virtual	~Clocked ()
	Virtual destructor due to inheritance. More...

void	resetClock () const
	Reset the object's clock using the current global tick value. More...

virtual void	clockPeriodUpdated ()
	A hook subclasses can implement so they can do any extra work that's needed when the clock rate is changed. More...

Private Member Functions
void	release ()
	Release the memory after being busy and send a retry if a request was rejected in the meanwhile. More...

void	dequeue ()
	Dequeue a packet from our internal packet queue and move it to the port where it will be sent as soon as possible. More...

Tick	getLatency () const
	Detemine the latency. More...

Private Attributes
MemoryPort	port

const Tick	latency
	Latency from that a request is accepted until the response is ready to be sent. More...

const Tick	latency_var
	Fudge factor added to the latency. More...

std::list< DeferredPacket >	packetQueue
	Internal (unbounded) storage to mimic the delay caused by the actual memory access. More...

const double	bandwidth
	Bandwidth in ticks per byte. More...

bool	isBusy
	Track the state of the memory as either idle or busy, no need for an enum with only two states. More...

bool	retryReq
	Remember if we have to retry an outstanding request that arrived while we were busy. More...

bool	retryResp
	Remember if we failed to send a response and are awaiting a retry. More...

EventFunctionWrapper	releaseEvent

EventFunctionWrapper	dequeueEvent

std::unique_ptr< Packet >	pendingDelete
	Upstream caches need this packet until true is returned, so hold it for deletion until a subsequent call. More...

Additional Inherited Members
Public Types inherited from AbstractMemory
typedef AbstractMemoryParams	Params

Public Types inherited from ClockedObject
typedef ClockedObjectParams	Params
	Parameters of ClockedObject. More...

Public Types inherited from SimObject
typedef SimObjectParams	Params

Static Public Member Functions inherited from SimObject
static void	serializeAll (CheckpointOut &cp)
	Serialize all SimObjects in the system. More...

static SimObject *	find (const char *name)
	Find the SimObject with the given name and return a pointer to it. More...

Static Public Member Functions inherited from Serializable
static const std::string &	currentSection ()
	Gets the fully-qualified name of the active section. More...

static void	serializeAll (const std::string &cpt_dir)
	Serializes all the SimObjects. More...

static void	unserializeGlobals (CheckpointIn &cp)

Public Attributes inherited from ClockedObject
PowerState *	powerState

Protected Attributes inherited from AbstractMemory
AddrRange	range

uint8_t *	pmemAddr

MemBackdoor	backdoor

const bool	confTableReported

const bool	inAddrMap

const bool	kvmMap

std::list< LockedAddr >	lockedAddrList

System *	_system
	Pointer to the System object. More...

AbstractMemory::MemStats	stats

Protected Attributes inherited from SimObject
const SimObjectParams *	_params
	Cached copy of the object parameters. More...

Protected Attributes inherited from EventManager
EventQueue *	eventq
	A pointer to this object's event queue. More...

Detailed Description

The simple memory is a basic single-ported memory controller with a configurable throughput and latency.

See also: gem5 Memory System

Definition at line 61 of file simple_mem.hh.

Constructor & Destructor Documentation

◆ SimpleMemory()

SimpleMemory::SimpleMemory ( const SimpleMemoryParams * p )

Definition at line 47 of file simple_mem.cc.

References release().

Member Function Documentation

◆ dequeue()

void SimpleMemory::dequeue ( )

private

Dequeue a packet from our internal packet queue and move it to the port where it will be sent as soon as possible.

Definition at line 201 of file simple_mem.cc.

References curTick(), dequeueEvent, DPRINTF, Draining, Drainable::drainState(), packetQueue, SimpleMemory::DeferredPacket::pkt, port, EventManager::reschedule(), retryResp, ResponsePort::sendTimingResp(), and Drainable::signalDrainDone().

Referenced by recvRespRetry().

◆ drain()

DrainState SimpleMemory::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 Drainable.

Definition at line 251 of file simple_mem.cc.

References DPRINTF, Drained, Draining, and packetQueue.

◆ getLatency()

Tick SimpleMemory::getLatency ( ) const

private

Detemine the latency.

Returns: the latency seen by the current packet

Definition at line 226 of file simple_mem.cc.

References latency, latency_var, Random::random(), and random_mt.

Referenced by recvAtomic(), and recvTimingReq().

◆ getPort()

Port & SimpleMemory::getPort	(	const std::string &	if_name,
		PortID	idx = `InvalidPortID`
	)

overridevirtual

Get a port with a given name and index.

This is used at binding time and returns a reference to a protocol-agnostic port.

gem5 has a request and response port interface. All memory objects are connected together via ports. These ports provide a rigid interface between these memory objects. These ports implement three different memory system modes: timing, atomic, and functional. The most important mode is the timing mode and here timing mode is used for conducting cycle-level timing experiments. The other modes are only used in special circumstances and should not be used to conduct cycle-level timing experiments. The other modes are only used in special circumstances. These ports allow SimObjects to communicate with each other.

Parameters

if_name	Port name
idx	Index in the case of a VectorPort

Returns: A reference to the given port

Reimplemented from SimObject.

Definition at line 241 of file simple_mem.cc.

References SimObject::getPort(), and port.

◆ init()

void SimpleMemory::init ( )

overridevirtual

init() is called after all C++ SimObjects have been created and all ports are connected.

Initializations that are independent of unserialization but rely on a fully instantiated and connected SimObject graph should be done here.

Reimplemented from SimObject.

Definition at line 58 of file simple_mem.cc.

References SimObject::init(), Port::isConnected(), port, and ResponsePort::sendRangeChange().

◆ recvAtomic()

Tick SimpleMemory::recvAtomic ( PacketPtr pkt )

protected

Definition at line 70 of file simple_mem.cc.

References AbstractMemory::access(), Packet::cacheResponding(), getLatency(), and panic_if.

Referenced by recvAtomicBackdoor(), and recvTimingReq().

◆ recvAtomicBackdoor()

Tick SimpleMemory::recvAtomicBackdoor	(	PacketPtr	pkt,
		MemBackdoorPtr &	_backdoor
	)

protected

Definition at line 80 of file simple_mem.cc.

References AbstractMemory::backdoor, latency, MemBackdoor::ptr(), and recvAtomic().

◆ recvFunctional()

void SimpleMemory::recvFunctional ( PacketPtr pkt )

protected

Definition at line 90 of file simple_mem.cc.

References AbstractMemory::functionalAccess(), SimObject::name(), MipsISA::p, packetQueue, Packet::popLabel(), Packet::pushLabel(), and Packet::trySatisfyFunctional().

◆ recvRespRetry()

void SimpleMemory::recvRespRetry ( )

protected

Definition at line 233 of file simple_mem.cc.

References dequeue(), and retryResp.

◆ recvTimingReq()

bool SimpleMemory::recvTimingReq ( PacketPtr pkt )

protected

◆ release()

void SimpleMemory::release ( )

private

Release the memory after being busy and send a retry if a request was rejected in the meanwhile.

Definition at line 190 of file simple_mem.cc.

References isBusy, port, retryReq, and ResponsePort::sendRetryReq().

Referenced by SimpleMemory().

Member Data Documentation

◆ bandwidth

const double SimpleMemory::bandwidth

private

Bandwidth in ticks per byte.

The regulation affects the acceptance rate of requests and the queueing takes place after the regulation.

Definition at line 125 of file simple_mem.hh.

Referenced by recvTimingReq().

◆ dequeueEvent

EventFunctionWrapper SimpleMemory::dequeueEvent

private

Definition at line 159 of file simple_mem.hh.

Referenced by dequeue(), and recvTimingReq().

◆ isBusy

bool SimpleMemory::isBusy

private

Track the state of the memory as either idle or busy, no need for an enum with only two states.

Definition at line 131 of file simple_mem.hh.

Referenced by recvTimingReq(), and release().

◆ latency

const Tick SimpleMemory::latency

private

Latency from that a request is accepted until the response is ready to be sent.

Definition at line 106 of file simple_mem.hh.

Referenced by getLatency(), and recvAtomicBackdoor().

◆ latency_var

const Tick SimpleMemory::latency_var

private

Fudge factor added to the latency.

Definition at line 111 of file simple_mem.hh.

Referenced by getLatency().

◆ packetQueue

std::list<DeferredPacket> SimpleMemory::packetQueue

private

Internal (unbounded) storage to mimic the delay caused by the actual memory access.

Note that this is where the packet spends the memory latency.

Definition at line 118 of file simple_mem.hh.

Referenced by dequeue(), drain(), recvFunctional(), and recvTimingReq().

◆ pendingDelete

std::unique_ptr<Packet> SimpleMemory::pendingDelete

private

Upstream caches need this packet until true is returned, so hold it for deletion until a subsequent call.

Definition at line 172 of file simple_mem.hh.

Referenced by recvTimingReq().

◆ port

MemoryPort SimpleMemory::port

private

Definition at line 100 of file simple_mem.hh.

Referenced by dequeue(), getPort(), init(), and release().

◆ releaseEvent

EventFunctionWrapper SimpleMemory::releaseEvent

private

Definition at line 151 of file simple_mem.hh.

Referenced by recvTimingReq().

◆ retryReq

bool SimpleMemory::retryReq

private

Remember if we have to retry an outstanding request that arrived while we were busy.

Definition at line 137 of file simple_mem.hh.

Referenced by recvTimingReq(), and release().

◆ retryResp

bool SimpleMemory::retryResp

private

Remember if we failed to send a response and are awaiting a retry.

This is only used as a check.

Definition at line 143 of file simple_mem.hh.

Referenced by dequeue(), recvRespRetry(), and recvTimingReq().

The documentation for this class was generated from the following files:

mem/simple_mem.hh
mem/simple_mem.cc

Classes

Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ SimpleMemory()

Member Function Documentation

◆ dequeue()

◆ drain()

◆ getLatency()

◆ getPort()

◆ init()

◆ recvAtomic()

◆ recvAtomicBackdoor()

◆ recvFunctional()

◆ recvRespRetry()

◆ recvTimingReq()

◆ release()

Member Data Documentation

◆ bandwidth

◆ dequeueEvent

◆ isBusy

◆ latency

◆ latency_var

◆ packetQueue

◆ pendingDelete

◆ port

◆ releaseEvent

◆ retryReq

◆ retryResp