#include <signature_path_v2.hh>

Inheritance diagram for SignaturePathPrefetcherV2:

Classes
struct	GlobalHistoryEntry
	Global History Register entry datatype. More...

Public Member Functions
	SignaturePathPrefetcherV2 (const SignaturePathPrefetcherV2Params *p)
	Copyright (c) 2018 Metempsy Technology Consulting All rights reserved. More...

	~SignaturePathPrefetcherV2 ()

Public Member Functions inherited from SignaturePathPrefetcher
	SignaturePathPrefetcher (const SignaturePathPrefetcherParams *p)
	Copyright (c) 2018 Metempsy Technology Consulting All rights reserved. More...

	~SignaturePathPrefetcher ()

void	calculatePrefetch (const PrefetchInfo &pfi, std::vector< AddrPriority > &addresses) override

Public Member Functions inherited from QueuedPrefetcher
	QueuedPrefetcher (const QueuedPrefetcherParams *p)

virtual	~QueuedPrefetcher ()

void	notify (const PacketPtr &pkt, const PrefetchInfo &pfi) override
	Notify prefetcher of cache access (may be any access or just misses, depending on cache parameters.) More...

void	insert (const PacketPtr &pkt, PrefetchInfo &new_pfi, int32_t priority)

PacketPtr	getPacket () override

Tick	nextPrefetchReadyTime () const override

void	regStats () override
	Register local statistics. More...

Public Member Functions inherited from BasePrefetcher
	BasePrefetcher (const BasePrefetcherParams *p)

virtual	~BasePrefetcher ()

virtual void	setCache (BaseCache *_cache)

virtual void	notifyFill (const PacketPtr &pkt)
	Notify prefetcher of cache fill. More...

void	regProbeListeners () override
	Register probe points for this object. More...

void	probeNotify (const PacketPtr &pkt, bool miss)
	Process a notification event from the ProbeListener. More...

void	addEventProbe (SimObject obj, const char name)
	Add a SimObject and a probe name to listen events from. More...

void	addTLB (BaseTLB *tlb)
	Add a BaseTLB object to be used whenever a translation is needed. 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...

Enums::PwrState	pwrState () const

std::string	pwrStateName () const

std::vector< double >	pwrStateWeights () const
	Returns the percentage residency for each power state. More...

void	computeStats ()
	Record stats values like state residency by computing the time difference from previous update. More...

void	pwrState (Enums::PwrState)

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

	SimObject (const Params *_params)

virtual	~SimObject ()

virtual const std::string	name () const

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

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

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

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

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

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

	EventManager (EventManager *em)

	EventManager (EventQueue *eq)

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)

void	setCurTick (Tick newVal)

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 ()=delete

	Group (const Group &)=delete

Group &	operator= (const Group &)=delete

	Group (Group parent, const char name=nullptr)
	Construct a new statistics group. More...

virtual	~Group ()

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...

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

Private Member Functions
double	calculateLookaheadConfidence (PatternEntry const &sig, PatternStrideEntry const &lookahead) const override
	Computes the lookahead path confidence of the provided pattern entry. More...

double	calculatePrefetchConfidence (PatternEntry const &sig, PatternStrideEntry const &lookahead) const override
	Computes the prefetch confidence of the provided pattern entry. More...

void	increasePatternEntryCounter (PatternEntry &pattern_entry, PatternStrideEntry &pstride_entry) override
	Increases the counter of a given PatternEntry/PatternStrideEntry. More...

void	handleSignatureTableMiss (stride_t current_block, signature_t &new_signature, double &new_conf, stride_t &new_stride) override
	Whenever a new SignatureEntry is allocated, it computes the new signature to be used with the new entry, the resulting stride and the initial path confidence of the new entry. More...

void	auxiliaryPrefetcher (Addr ppn, stride_t current_block, bool is_secure, std::vector< AddrPriority > &addresses) override
	In this version of the Signature Path Prefetcher, there is no auxiliary prefetcher, so this function does not perform any actions. More...

virtual void	handlePageCrossingLookahead (signature_t signature, stride_t last_offset, stride_t delta, double path_confidence) override
	Handles the situation when the lookahead process has crossed the boundaries of the current page. More...

Private Attributes
AssociativeSet< GlobalHistoryEntry >	globalHistoryRegister
	Global History Register. More...

Additional Inherited Members
Public Types inherited from QueuedPrefetcher
using	AddrPriority = std::pair< Addr, int32_t >

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 ()
	Get the fully-qualified name of the active section. More...

static void	serializeAll (const std::string &cpt_dir)

static void	unserializeGlobals (CheckpointIn &cp)

Static Public Attributes inherited from Serializable
static int	ckptCount = 0

static int	ckptMaxCount = 0

static int	ckptPrevCount = -1

Protected Types inherited from SignaturePathPrefetcher
typedef uint16_t	signature_t
	Signature type. More...

typedef int16_t	stride_t
	Stride type. More...

Protected Types inherited from QueuedPrefetcher
using	const_iterator = std::list< DeferredPacket >::const_iterator

using	iterator = std::list< DeferredPacket >::iterator

Protected Member Functions inherited from SignaturePathPrefetcher
signature_t	updateSignature (signature_t sig, stride_t str) const
	Generates a new signature from an existing one and a new stride. More...

void	addPrefetch (Addr ppn, stride_t last_block, stride_t delta, double path_confidence, signature_t signature, bool is_secure, std::vector< AddrPriority > &addresses)
	Generates an address to be prefetched. More...

SignatureEntry &	getSignatureEntry (Addr ppn, bool is_secure, stride_t block, bool &miss, stride_t &stride, double &initial_confidence)
	Obtains the SignatureEntry of the given page, if the page is not found, it allocates a new one, replacing an existing entry if needed It also provides the stride of the current block and the initial path confidence of the corresponding entry. More...

PatternEntry &	getPatternEntry (Addr signature)
	Obtains the PatternEntry of the given signature, if the signature is not found, it allocates a new one, replacing an existing entry if needed. More...

void	updatePatternTable (Addr signature, stride_t stride)
	Updates the pattern table with the provided signature and stride. More...

Protected Member Functions inherited from BasePrefetcher
bool	observeAccess (const PacketPtr &pkt, bool miss) const
	Determine if this access should be observed. More...

bool	inCache (Addr addr, bool is_secure) const
	Determine if address is in cache. More...

bool	inMissQueue (Addr addr, bool is_secure) const
	Determine if address is in cache miss queue. More...

bool	hasBeenPrefetched (Addr addr, bool is_secure) const

bool	samePage (Addr a, Addr b) const
	Determine if addresses are on the same page. More...

Addr	blockAddress (Addr a) const
	Determine the address of the block in which a lays. More...

Addr	blockIndex (Addr a) const
	Determine the address of a at block granularity. More...

Addr	pageAddress (Addr a) const
	Determine the address of the page in which a lays. More...

Addr	pageOffset (Addr a) const
	Determine the page-offset of a. More...

Addr	pageIthBlockAddress (Addr page, uint32_t i) const
	Build the address of the i-th block inside the page. More...

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...

Protected Attributes inherited from SignaturePathPrefetcher
const unsigned	stridesPerPatternEntry
	Number of strides stored in each pattern entry. More...

const uint8_t	signatureShift
	Number of bits to shift when generating a new signature. More...

const signature_t	signatureBits
	Size of the signature, in bits. More...

const double	prefetchConfidenceThreshold
	Minimum confidence to issue a prefetch. More...

const double	lookaheadConfidenceThreshold
	Minimum confidence to keep navigating lookahead entries. More...

AssociativeSet< SignatureEntry >	signatureTable
	Signature table. More...

AssociativeSet< PatternEntry >	patternTable
	Pattern table. More...

Protected Attributes inherited from QueuedPrefetcher
std::list< DeferredPacket >	pfq

std::list< DeferredPacket >	pfqMissingTranslation

const unsigned	queueSize
	Maximum size of the prefetch queue. More...

const unsigned	missingTranslationQueueSize
	Maximum size of the queue holding prefetch requests with missing address translations. More...

const Cycles	latency
	Cycles after generation when a prefetch can first be issued. More...

const bool	queueSquash
	Squash queued prefetch if demand access observed. More...

const bool	queueFilter
	Filter prefetches if already queued. More...

const bool	cacheSnoop
	Snoop the cache before generating prefetch (cheating basically) More...

const bool	tagPrefetch
	Tag prefetch with PC of generating access? More...

const unsigned int	throttleControlPct
	Percentage of requests that can be throttled. More...

Stats::Scalar	pfIdentified

Stats::Scalar	pfBufferHit

Stats::Scalar	pfInCache

Stats::Scalar	pfRemovedFull

Stats::Scalar	pfSpanPage

Protected Attributes inherited from BasePrefetcher
BaseCache *	cache
	Pointr to the parent cache. More...

unsigned	blkSize
	The block size of the parent cache. More...

unsigned	lBlkSize
	log_2(block size of the parent cache). More...

const bool	onMiss
	Only consult prefetcher on cache misses? More...

const bool	onRead
	Consult prefetcher on reads? More...

const bool	onWrite
	Consult prefetcher on reads? More...

const bool	onData
	Consult prefetcher on data accesses? More...

const bool	onInst
	Consult prefetcher on instruction accesses? More...

const MasterID	masterId
	Request id for prefetches. More...

const Addr	pageBytes

const bool	prefetchOnAccess
	Prefetch on every access, not just misses. More...

const bool	useVirtualAddresses
	Use Virtual Addresses for prefetching. More...

Stats::Scalar	pfIssued

uint64_t	issuedPrefetches
	Total prefetches issued. More...

uint64_t	usefulPrefetches
	Total prefetches that has been useful. More...

BaseTLB *	tlb
	Registered tlb for address translations. More...

Protected Attributes inherited from ClockedObject
Enums::PwrState	_currPwrState
	To keep track of the current power state. More...

Tick	prvEvalTick

ClockedObject::ClockedObjectStats	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

Definition at line 52 of file signature_path_v2.hh.

Constructor & Destructor Documentation

◆ SignaturePathPrefetcherV2()

SignaturePathPrefetcherV2::SignaturePathPrefetcherV2 ( const SignaturePathPrefetcherV2Params * p )

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.

Authors: Javier Bueno

Definition at line 39 of file signature_path_v2.cc.

Referenced by auxiliaryPrefetcher(), and handlePageCrossingLookahead().

◆ ~SignaturePathPrefetcherV2()

SignaturePathPrefetcherV2::~SignaturePathPrefetcherV2 ( )

inline

Definition at line 94 of file signature_path_v2.hh.

Member Function Documentation

◆ auxiliaryPrefetcher()

void SignaturePathPrefetcherV2::auxiliaryPrefetcher	(	Addr	ppn,
		stride_t	current_block,
		bool	is_secure,
		std::vector< AddrPriority > &	addresses
	)

inlineoverrideprivatevirtual

In this version of the Signature Path Prefetcher, there is no auxiliary prefetcher, so this function does not perform any actions.

Reimplemented from SignaturePathPrefetcher.

Definition at line 84 of file signature_path_v2.hh.

References SignaturePathPrefetcherV2::GlobalHistoryEntry::delta, handlePageCrossingLookahead(), MipsISA::p, SignaturePathPrefetcherV2::GlobalHistoryEntry::signature, and SignaturePathPrefetcherV2().

◆ calculateLookaheadConfidence()

double SignaturePathPrefetcherV2::calculateLookaheadConfidence	(	PatternEntry const &	sig,
		PatternStrideEntry const &	lookahead
	)		const

overrideprivatevirtual

Computes the lookahead path confidence of the provided pattern entry.

Parameters

sig	the PatternEntry to use
lookahead	PatternStrideEntry within the provided PatternEntry

Returns: the computed confidence factor

maximum confidence is 0.95, guaranteeing that current confidence will eventually fall beyond the threshold

Reimplemented from SignaturePathPrefetcher.

Definition at line 79 of file signature_path_v2.cc.

References SignaturePathPrefetcher::PatternStrideEntry::counter, SignaturePathPrefetcher::PatternEntry::counter, BasePrefetcher::issuedPrefetches, and BasePrefetcher::usefulPrefetches.

◆ calculatePrefetchConfidence()

double SignaturePathPrefetcherV2::calculatePrefetchConfidence	(	PatternEntry const &	sig,
		PatternStrideEntry const &	entry
	)		const

overrideprivatevirtual

Computes the prefetch confidence of the provided pattern entry.

Parameters

sig	the PatternEntry to use
entry	PatternStrideEntry within the provided PatternEntry

Returns: the computed confidence factor

Reimplemented from SignaturePathPrefetcher.

Definition at line 88 of file signature_path_v2.cc.

References SignaturePathPrefetcher::PatternStrideEntry::counter, and SignaturePathPrefetcher::PatternEntry::counter.

◆ handlePageCrossingLookahead()

void SignaturePathPrefetcherV2::handlePageCrossingLookahead	(	signature_t	signature,
		stride_t	last_offset,
		stride_t	delta,
		double	path_confidence
	)

overrideprivatevirtual

Handles the situation when the lookahead process has crossed the boundaries of the current page.

This is not fully described in the paper that was used to implement this code, however, the article describing the upgraded version of this prefetcher provides some details. For this prefetcher, there are no specific actions to be done.

Parameters

signature	the lookahead signature that crossed the page
delta	the current stride that caused it
last_offset	the last accessed block within the page
path_confidence	the path confidence at the moment of crossing

Reimplemented from SignaturePathPrefetcher.

Definition at line 116 of file signature_path_v2.cc.

References SignaturePathPrefetcherV2::GlobalHistoryEntry::confidence, SignaturePathPrefetcherV2::GlobalHistoryEntry::delta, globalHistoryRegister, SignaturePathPrefetcherV2::GlobalHistoryEntry::lastBlock, SignaturePathPrefetcherV2::GlobalHistoryEntry::signature, and SignaturePathPrefetcherV2().

Referenced by auxiliaryPrefetcher().

◆ handleSignatureTableMiss()

void SignaturePathPrefetcherV2::handleSignatureTableMiss	(	stride_t	current_block,
		signature_t &	new_signature,
		double &	new_conf,
		stride_t &	new_stride
	)

overrideprivatevirtual

Whenever a new SignatureEntry is allocated, it computes the new signature to be used with the new entry, the resulting stride and the initial path confidence of the new entry.

Parameters

current_block	accessed block within the page of the associated entry
new_signature	new signature of the allocated entry
new_conf	the initial path confidence of this entry
new_stride	the resulting current stride

Reimplemented from SignaturePathPrefetcher.

Definition at line 51 of file signature_path_v2.cc.

References globalHistoryRegister.