#include <access_map_pattern_matching.hh>

Inheritance diagram for gem5::prefetch::AccessMapPatternMatching:

Classes
struct	AccessMapEntry
	AccessMapEntry data type. More...

Public Member Functions
	AccessMapPatternMatching (const AccessMapPatternMatchingParams &p)

	~AccessMapPatternMatching ()=default

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

void	calculatePrefetch (const Base::PrefetchInfo &pfi, std::vector< Queued::AddrPriority > &addresses, const CacheAccessor &cache)

Public Member Functions inherited from gem5::ClockedObject
	ClockedObject (const ClockedObjectParams &p)

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

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

Public Member Functions inherited from gem5::SimObject
const Params &	params () const

	SimObject (const Params &p)

virtual	~SimObject ()

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

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

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

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

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

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

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

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

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

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

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

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

Public Member Functions inherited from gem5::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.

void	setCurTick (Tick newVal)

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

	EventManager (EventManager *em)

	EventManager (EventQueue *eq)

Public Member Functions inherited from gem5::Serializable
	Serializable ()

virtual	~Serializable ()

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

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

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

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

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.

Public Member Functions inherited from gem5::statistics::Group
	Group (Group parent, const char name=nullptr)
	Construct a new statistics group.

virtual	~Group ()

virtual void	regStats ()
	Callback to set stat parameters.

virtual void	resetStats ()
	Callback to reset stats.

virtual void	preDumpStats ()
	Callback before stats are dumped.

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

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

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

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

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

void	mergeStatGroup (Group *block)
	Merge the contents (stats & children) of a block to this block.

	Group ()=delete

	Group (const Group &)=delete

Group &	operator= (const Group &)=delete

Public Member Functions inherited from gem5::Named
	Named (const std::string &name_)

virtual	~Named ()=default

virtual std::string	name () const

Public Member Functions inherited from gem5::Clocked
void	updateClockPeriod ()
	Update the tick to the current tick.

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.

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

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.

uint64_t	frequency () const

Tick	clockPeriod () const

double	voltage () const

Cycles	ticksToCycles (Tick t) const

Tick	cyclesToTicks (Cycles c) const

Private Types
enum	AccessMapState { AM_INIT , AM_PREFETCH , AM_ACCESS , AM_INVALID }
	Data type representing the state of a cacheline in the access map. More...

Private Member Functions
bool	checkCandidate (std::vector< AccessMapState > const &states, Addr current, int stride) const
	Given a target cacheline, this function checks if the cachelines that follow the provided stride have been accessed.

AccessMapEntry *	getAccessMapEntry (Addr am_addr, bool is_secure)
	Obtain an AccessMapEntry from the AccessMapTable, if the entry is not found a new one is initialized and inserted.

void	setEntryState (AccessMapEntry &entry, Addr block, enum AccessMapState state)
	Updates the state of a block within an AccessMapEntry, also updates the prefetcher metrics.

void	processEpochEvent ()
	This event constitues the epoch of the statistics that keep track of the prefetcher accuracy, when this event triggers, the prefetcher degree is adjusted and the statistics counters are reset.

Private Attributes
const unsigned	blkSize
	Cacheline size used by the prefetcher using this object.

const unsigned	limitStride
	Limit the stride checking to -limitStride/+limitStride.

const unsigned	startDegree
	Maximum number of prefetch generated.

const uint64_t	hotZoneSize
	Amount of memory covered by a hot zone.

const double	highCoverageThreshold
	A prefetch coverage factor bigger than this is considered high.

const double	lowCoverageThreshold
	A prefetch coverage factor smaller than this is considered low.

const double	highAccuracyThreshold
	A prefetch accuracy factor bigger than this is considered high.

const double	lowAccuracyThreshold
	A prefetch accuracy factor smaller than this is considered low.

const double	highCacheHitThreshold
	A cache hit ratio bigger than this is considered high.

const double	lowCacheHitThreshold
	A cache hit ratio smaller than this is considered low.

const Cycles	epochCycles
	Cycles in an epoch period.

const Tick	offChipMemoryLatency
	Off chip memory latency to use for the epoch bandwidth calculation.

AssociativeSet< AccessMapEntry >	accessMapTable
	Access map table.

uint64_t	numGoodPrefetches
	Number of good prefetches.

uint64_t	numTotalPrefetches
	Number of prefetches issued.

uint64_t	numRawCacheMisses
	Number of raw cache misses.

uint64_t	numRawCacheHits
	Number of raw cache hits.

unsigned	degree
	Current degree.

unsigned	usefulDegree
	Current useful degree.

EventFunctionWrapper	epochEvent

Additional Inherited Members
Public Types inherited from gem5::ClockedObject
using	Params = ClockedObjectParams
	Parameters of ClockedObject.

Public Types inherited from gem5::SimObject
typedef SimObjectParams	Params

Static Public Member Functions inherited from gem5::SimObject
static void	serializeAll (const std::string &cpt_dir)
	Create a checkpoint by serializing all SimObjects in the system.

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

static void	setSimObjectResolver (SimObjectResolver *resolver)
	There is a single object name resolver, and it is only set when simulation is restoring from checkpoints.

static SimObjectResolver *	getSimObjectResolver ()
	There is a single object name resolver, and it is only set when simulation is restoring from checkpoints.

Static Public Member Functions inherited from gem5::Serializable
static const std::string &	currentSection ()
	Gets the fully-qualified name of the active section.

static void	generateCheckpointOut (const std::string &cpt_dir, std::ofstream &outstream)
	Generate a checkpoint file so that the serialization can be routed to it.

Public Attributes inherited from gem5::ClockedObject
PowerState *	powerState

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 Member Functions inherited from gem5::Clocked
	Clocked (ClockDomain &clk_domain)
	Create a clocked object and set the clock domain based on the parameters.

	Clocked (Clocked &)=delete

Clocked &	operator= (Clocked &)=delete

virtual	~Clocked ()
	Virtual destructor due to inheritance.

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

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

Protected Attributes inherited from gem5::SimObject
const SimObjectParams &	_params
	Cached copy of the object parameters.

Protected Attributes inherited from gem5::EventManager
EventQueue *	eventq
	A pointer to this object's event queue.

Detailed Description

Definition at line 55 of file access_map_pattern_matching.hh.

Member Enumeration Documentation

◆ AccessMapState

enum gem5::prefetch::AccessMapPatternMatching::AccessMapState

private

Data type representing the state of a cacheline in the access map.

Enumerator
AM_INIT
AM_PREFETCH
AM_ACCESS
AM_INVALID

Definition at line 83 of file access_map_pattern_matching.hh.

Constructor & Destructor Documentation

◆ AccessMapPatternMatching()

gem5::prefetch::AccessMapPatternMatching::AccessMapPatternMatching ( const AccessMapPatternMatchingParams & p )

Definition at line 42 of file access_map_pattern_matching.cc.

References processEpochEvent().

◆ ~AccessMapPatternMatching()

gem5::prefetch::AccessMapPatternMatching::~AccessMapPatternMatching ( )

default

Member Function Documentation

◆ calculatePrefetch()

void gem5::prefetch::AccessMapPatternMatching::calculatePrefetch	(	const Base::PrefetchInfo &	pfi,
		std::vector< Queued::AddrPriority > &	addresses,
		const CacheAccessor &	cache )

Create a contiguous copy of the 3 entries states. With this, we avoid doing boundaries checking in the loop that looks for prefetch candidates, mark out of range positions with AM_INVALID

am_entry_prev->states => states[ 0 .. lines_per_zone-1] am_entry_curr->states => states[ lines_per_zone .. 2*lines_per_zone-1] am_entry_next->states => states[2*lines_per_zone .. 3*lines_per_zone-1]

Definition at line 160 of file access_map_pattern_matching.cc.

References AM_ACCESS, AM_INVALID, AM_PREFETCH, blkSize, checkCandidate(), degree, getAccessMapEntry(), gem5::prefetch::Base::PrefetchInfo::getAddr(), hotZoneSize, gem5::prefetch::Base::PrefetchInfo::isSecure(), limitStride, gem5::MaxAddr, setEntryState(), gem5::prefetch::AccessMapPatternMatching::AccessMapEntry::states, and gem5::ArmISA::stride.

Referenced by gem5::prefetch::AMPM::calculatePrefetch(), and gem5::prefetch::SlimAMPM::calculatePrefetch().

◆ checkCandidate()

bool gem5::prefetch::AccessMapPatternMatching::checkCandidate	(	std::vector< AccessMapState > const &	states,
		Addr	current,
		int	stride ) const

inlineprivate

Given a target cacheline, this function checks if the cachelines that follow the provided stride have been accessed.

If so, the line is considered a good candidate.

Parameters

states	vector containing the states of three contiguous hot zones
current	target block (cacheline)
stride	access stride to obtain the reference cachelines

Returns: true if current is a prefetch candidate

Definition at line 148 of file access_map_pattern_matching.hh.

References AM_ACCESS, AM_INVALID, gem5::ArmISA::s, and gem5::ArmISA::stride.

Referenced by calculatePrefetch().

◆ getAccessMapEntry()

AccessMapPatternMatching::AccessMapEntry * gem5::prefetch::AccessMapPatternMatching::getAccessMapEntry	(	Addr	am_addr,
		bool	is_secure )

private

Obtain an AccessMapEntry from the AccessMapTable, if the entry is not found a new one is initialized and inserted.

Parameters

am_addr	address of the hot zone
is_secure	whether the address belongs to the secure memory area

Returns: the corresponding entry

Definition at line 109 of file access_map_pattern_matching.cc.

References accessMapTable.

Referenced by calculatePrefetch().

◆ processEpochEvent()

void gem5::prefetch::AccessMapPatternMatching::processEpochEvent ( )

private

This event constitues the epoch of the statistics that keep track of the prefetcher accuracy, when this event triggers, the prefetcher degree is adjusted and the statistics counters are reset.

Definition at line 75 of file access_map_pattern_matching.cc.

References gem5::Clocked::clockEdge(), gem5::Clocked::cyclesToTicks(), degree, epochCycles, epochEvent, highAccuracyThreshold, highCacheHitThreshold, highCoverageThreshold, lowAccuracyThreshold, lowCacheHitThreshold, lowCoverageThreshold, numGoodPrefetches, numRawCacheHits, numRawCacheMisses, numTotalPrefetches, offChipMemoryLatency, gem5::EventManager::schedule(), and usefulDegree.

Referenced by AccessMapPatternMatching().

◆ setEntryState()

void gem5::prefetch::AccessMapPatternMatching::setEntryState	(	AccessMapEntry &	entry,
		Addr	block,
		enum AccessMapState	state )

private

Updates the state of a block within an AccessMapEntry, also updates the prefetcher metrics.

Parameters

entry	AccessMapEntry to update
block	cacheline within the hot zone
state	new state

Definition at line 125 of file access_map_pattern_matching.cc.

References AM_ACCESS, AM_INIT, AM_PREFETCH, numGoodPrefetches, numRawCacheHits, numRawCacheMisses, numTotalPrefetches, panic, state, and gem5::prefetch::AccessMapPatternMatching::AccessMapEntry::states.

Referenced by calculatePrefetch().

◆ startup()

void gem5::prefetch::AccessMapPatternMatching::startup ( )

overridevirtual

startup() is the final initialization call before simulation.

All state is initialized (including unserialized state, if any, such as the curTick() value), so this is the appropriate place to schedule initial event(s) for objects that need them.

Reimplemented from gem5::SimObject.

Definition at line 69 of file access_map_pattern_matching.cc.

References gem5::Clocked::clockEdge(), epochCycles, epochEvent, and gem5::EventManager::schedule().

Member Data Documentation

◆ accessMapTable

AssociativeSet<AccessMapEntry> gem5::prefetch::AccessMapPatternMatching::accessMapTable

private

Access map table.

Definition at line 112 of file access_map_pattern_matching.hh.

Referenced by getAccessMapEntry().

◆ blkSize

const unsigned gem5::prefetch::AccessMapPatternMatching::blkSize

private

Cacheline size used by the prefetcher using this object.

Definition at line 58 of file access_map_pattern_matching.hh.

Referenced by calculatePrefetch().

◆ degree

unsigned gem5::prefetch::AccessMapPatternMatching::degree

private

Current degree.

Definition at line 135 of file access_map_pattern_matching.hh.

Referenced by calculatePrefetch(), and processEpochEvent().

◆ epochCycles

const Cycles gem5::prefetch::AccessMapPatternMatching::epochCycles

private

Cycles in an epoch period.

Definition at line 78 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and startup().

◆ epochEvent

EventFunctionWrapper gem5::prefetch::AccessMapPatternMatching::epochEvent

private

Definition at line 185 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and startup().

◆ highAccuracyThreshold

const double gem5::prefetch::AccessMapPatternMatching::highAccuracyThreshold

private

A prefetch accuracy factor bigger than this is considered high.

Definition at line 70 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ highCacheHitThreshold

const double gem5::prefetch::AccessMapPatternMatching::highCacheHitThreshold

private

A cache hit ratio bigger than this is considered high.

Definition at line 74 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ highCoverageThreshold

const double gem5::prefetch::AccessMapPatternMatching::highCoverageThreshold

private

A prefetch coverage factor bigger than this is considered high.

Definition at line 66 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ hotZoneSize

const uint64_t gem5::prefetch::AccessMapPatternMatching::hotZoneSize

private

Amount of memory covered by a hot zone.

Definition at line 64 of file access_map_pattern_matching.hh.

Referenced by calculatePrefetch().

◆ limitStride

const unsigned gem5::prefetch::AccessMapPatternMatching::limitStride

private

Limit the stride checking to -limitStride/+limitStride.

Definition at line 60 of file access_map_pattern_matching.hh.

Referenced by calculatePrefetch().

◆ lowAccuracyThreshold

const double gem5::prefetch::AccessMapPatternMatching::lowAccuracyThreshold

private

A prefetch accuracy factor smaller than this is considered low.

Definition at line 72 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ lowCacheHitThreshold

const double gem5::prefetch::AccessMapPatternMatching::lowCacheHitThreshold

private

A cache hit ratio smaller than this is considered low.

Definition at line 76 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ lowCoverageThreshold

const double gem5::prefetch::AccessMapPatternMatching::lowCoverageThreshold

private

A prefetch coverage factor smaller than this is considered low.

Definition at line 68 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ numGoodPrefetches

uint64_t gem5::prefetch::AccessMapPatternMatching::numGoodPrefetches

private

Number of good prefetches.

State transitions from PREFETCH to ACCESS

Definition at line 118 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and setEntryState().

◆ numRawCacheHits

uint64_t gem5::prefetch::AccessMapPatternMatching::numRawCacheHits

private

Number of raw cache hits.

State transitions from ACCESS to ACCESS

Definition at line 133 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and setEntryState().

◆ numRawCacheMisses

uint64_t gem5::prefetch::AccessMapPatternMatching::numRawCacheMisses

private

Number of raw cache misses.

State transitions from INIT or PREFETCH to ACCESS

Definition at line 128 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and setEntryState().

◆ numTotalPrefetches

uint64_t gem5::prefetch::AccessMapPatternMatching::numTotalPrefetches

private

Number of prefetches issued.

State transitions from INIT to PREFETCH

Definition at line 123 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and setEntryState().

◆ offChipMemoryLatency

const Tick gem5::prefetch::AccessMapPatternMatching::offChipMemoryLatency

private

Off chip memory latency to use for the epoch bandwidth calculation.

Definition at line 80 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

◆ startDegree

const unsigned gem5::prefetch::AccessMapPatternMatching::startDegree

private

Maximum number of prefetch generated.

Definition at line 62 of file access_map_pattern_matching.hh.

◆ usefulDegree

unsigned gem5::prefetch::AccessMapPatternMatching::usefulDegree

private

Current useful degree.

Definition at line 137 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().

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

mem/cache/prefetch/access_map_pattern_matching.hh
mem/cache/prefetch/access_map_pattern_matching.cc

Classes

Public Member Functions

Private Types

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ AccessMapState

Constructor & Destructor Documentation

◆ AccessMapPatternMatching()

◆ ~AccessMapPatternMatching()

Member Function Documentation

◆ calculatePrefetch()

◆ checkCandidate()

◆ getAccessMapEntry()

◆ processEpochEvent()

◆ setEntryState()

◆ startup()

Member Data Documentation

◆ accessMapTable

◆ blkSize

◆ degree

◆ epochCycles

◆ epochEvent

◆ highAccuracyThreshold

◆ highCacheHitThreshold

◆ highCoverageThreshold

◆ hotZoneSize

◆ limitStride

◆ lowAccuracyThreshold

◆ lowCacheHitThreshold

◆ lowCoverageThreshold

◆ numGoodPrefetches

◆ numRawCacheHits

◆ numRawCacheMisses

◆ numTotalPrefetches

◆ offChipMemoryLatency

◆ startDegree

◆ usefulDegree