A fully associative LRU cache. More...

#include <fa_lru.hh>

Inheritance diagram for gem5::FALRU:

Classes
class	CacheTracking
	Mechanism that allows us to simultaneously collect miss statistics for multiple caches. More...

struct	PairHash
	Hash table type mapping addresses to cache block pointers. More...

Public Types
typedef FALRUBlk	BlkType
	Typedef the block type used in this class.

typedef FALRUParams	Params

Public Types inherited from gem5::BaseTags
typedef BaseTagsParams	Params

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

Public Types inherited from gem5::SimObject
typedef SimObjectParams	Params

Public Member Functions
	FALRU (const Params &p)
	Construct and initialize this cache tagstore.

	~FALRU ()

void	tagsInit () override
	Initialize blocks as FALRUBlk instances.

void	invalidate (CacheBlk *blk) override
	Invalidate a cache block.

CacheBlk *	accessBlock (const PacketPtr pkt, Cycles &lat, CachesMask *in_cache_mask)
	Access block and update replacement data.

CacheBlk *	accessBlock (const PacketPtr pkt, Cycles &lat) override
	Just a wrapper of above function to conform with the base interface.

CacheBlk *	findBlock (Addr addr, bool is_secure) const override
	Find the block in the cache, do not update the replacement data.

ReplaceableEntry *	findBlockBySetAndWay (int set, int way) const override
	Find a block given set and way.

CacheBlk *	findVictim (Addr addr, const bool is_secure, const std::size_t size, std::vector< CacheBlk * > &evict_blks, const uint64_t partition_id=0) override
	Find replacement victim based on address.

void	insertBlock (const PacketPtr pkt, CacheBlk *blk) override
	Insert the new block into the cache and update replacement data.

void	moveBlock (CacheBlk src_blk, CacheBlk dest_blk) override
	Move a block's metadata to another location decided by the replacement policy.

Addr	extractTag (Addr addr) const override
	Generate the tag from the addres.

Addr	regenerateBlkAddr (const CacheBlk *blk) const override
	Regenerate the block address from the tag.

bool	anyBlk (std::function< bool(CacheBlk &)> visitor) override
	Find if any of the blocks satisfies a condition.

Public Member Functions inherited from gem5::BaseTags
	BaseTags (const Params &p)

virtual	~BaseTags ()
	Destructor.

void	cleanupRefs ()
	Average in the reference count for valid blocks when the simulation exits.

void	computeStats ()
	Computes stats just prior to dump event.

std::string	print ()
	Print all tags used.

Addr	blkAlign (Addr addr) const
	Align an address to the block size.

int	extractBlkOffset (Addr addr) const
	Calculate the block offset of an address.

virtual void	setWayAllocationMax (int ways)
	Limit the allocation for the cache ways.

virtual int	getWayAllocationMax () const
	Get the way allocation mask limit.

void	forEachBlk (std::function< void(CacheBlk &)> visitor)
	Visit each block in the tags and apply a visitor.

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.

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

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

Protected Types
typedef std::pair< Addr, bool >	TagHashKey

typedef std::unordered_map< TagHashKey, FALRUBlk *, PairHash >	TagHash

Protected Member Functions
void	moveToHead (FALRUBlk *blk)
	Move a cache block to the MRU position.

void	moveToTail (FALRUBlk *blk)
	Move a cache block to the LRU position.

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
FALRUBlk *	blks
	The cache blocks.

FALRUBlk *	head
	The MRU block.

FALRUBlk *	tail
	The LRU block.

TagHash	tagHash
	The address hash table.

Protected Attributes inherited from gem5::BaseTags
const unsigned	blkSize
	The block size of the cache.

const Addr	blkMask
	Mask out all bits that aren't part of the block offset.

const unsigned	size
	The size of the cache.

const Cycles	lookupLatency
	The tag lookup latency of the cache.

System *	system
	System we are currently operating in.

BaseIndexingPolicy *	indexingPolicy
	Indexing policy.

partitioning_policy::PartitionManager *	partitionManager
	Partitioning manager.

const unsigned	warmupBound
	The number of tags that need to be touched to meet the warmup percentage.

bool	warmedUp
	Marked true when the cache is warmed up.

const unsigned	numBlocks
	the number of blocks in the cache

std::unique_ptr< uint8_t[]>	dataBlks
	The data blocks, 1 per cache block.

gem5::BaseTags::BaseTagStats	stats

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.

Private Attributes
CacheTracking	cacheTracking

Additional Inherited Members
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

Detailed Description

A fully associative LRU cache.

Keeps statistics for accesses to a number of cache sizes at once.

Definition at line 111 of file fa_lru.hh.

Member Typedef Documentation

◆ BlkType

typedef FALRUBlk gem5::FALRU::BlkType

Typedef the block type used in this class.

Definition at line 115 of file fa_lru.hh.

◆ Params

typedef FALRUParams gem5::FALRU::Params

Definition at line 156 of file fa_lru.hh.

◆ TagHash

typedef std::unordered_map<TagHashKey, FALRUBlk *, PairHash> gem5::FALRU::TagHash

protected

Definition at line 136 of file fa_lru.hh.

◆ TagHashKey

typedef std::pair<Addr, bool> gem5::FALRU::TagHashKey

protected

Definition at line 135 of file fa_lru.hh.

Constructor & Destructor Documentation

◆ FALRU()

gem5::FALRU::FALRU ( const Params & p )

Construct and initialize this cache tagstore.

Definition at line 68 of file fa_lru.cc.

References blks, gem5::BaseTags::blkSize, fatal, gem5::isPowerOf2(), gem5::BaseTags::numBlocks, gem5::BaseTags::partitionManager, and gem5::BaseTags::size.

◆ ~FALRU()

gem5::FALRU::~FALRU ( )

Definition at line 84 of file fa_lru.cc.

References blks.

Member Function Documentation

◆ accessBlock() [1/2]

CacheBlk * gem5::FALRU::accessBlock	(	const PacketPtr	pkt,
		Cycles &	lat )

overridevirtual

Just a wrapper of above function to conform with the base interface.

Implements gem5::BaseTags.

Definition at line 137 of file fa_lru.cc.

References accessBlock().

◆ accessBlock() [2/2]

CacheBlk * gem5::FALRU::accessBlock	(	const PacketPtr	pkt,
		Cycles &	lat,
		CachesMask *	in_cache_mask )

Access block and update replacement data.

May not succeed, in which case nullptr pointer is returned. This has all the implications of a cache access and should only be used as such. Returns tag lookup latency and the inCachesMask flags as a side effect.

Parameters

pkt	The packet holding the address to find.
lat	The latency of the tag lookup.
in_cache_mask	Mask indicating the caches in which the blk fits.

Returns: Pointer to the cache block.

Definition at line 143 of file fa_lru.cc.

References cacheTracking, findBlock(), gem5::Packet::getAddr(), gem5::FALRUBlk::inCachesMask, gem5::Packet::isSecure(), gem5::CacheEntry::isValid(), gem5::BaseTags::lookupLatency, gem5::ArmISA::mask, moveToHead(), and gem5::FALRU::CacheTracking::recordAccess().

Referenced by accessBlock().

◆ anyBlk()

bool gem5::FALRU::anyBlk ( std::function< bool(CacheBlk &)> visitor )

inlineoverridevirtual

Find if any of the blocks satisfies a condition.

The visitor should be a std::function that takes a cache block reference as its parameter. The visitor will terminate the traversal early if the condition is satisfied.

Parameters

visitor Visitor to call on each block.

Implements gem5::BaseTags.

Definition at line 260 of file fa_lru.hh.

References blks, gem5::ArmISA::i, and gem5::BaseTags::numBlocks.

◆ extractTag()

Addr gem5::FALRU::extractTag ( Addr addr ) const

inlineoverridevirtual

Generate the tag from the addres.

For fully associative this is just the block address.

Parameters

addr	The address to get the tag from.

Returns: The tag.

Reimplemented from gem5::BaseTags.

Definition at line 244 of file fa_lru.hh.

References gem5::X86ISA::addr, and gem5::BaseTags::blkAlign().

Referenced by findBlock().

◆ findBlock()

CacheBlk * gem5::FALRU::findBlock	(	Addr	addr,
		bool	is_secure ) const

overridevirtual

Find the block in the cache, do not update the replacement data.

Parameters

addr	The address to look for.
is_secure	True if the target memory space is secure.
asid	The address space ID.

Returns: Pointer to the cache block.

Reimplemented from gem5::BaseTags.

Definition at line 170 of file fa_lru.cc.

References gem5::X86ISA::addr, extractTag(), gem5::CacheEntry::getTag(), gem5::TaggedEntry::isSecure(), gem5::CacheEntry::isValid(), and tagHash.

Referenced by accessBlock().

◆ findBlockBySetAndWay()

ReplaceableEntry * gem5::FALRU::findBlockBySetAndWay	(	int	set,
		int	way ) const

overridevirtual

Find a block given set and way.

Parameters

set	The set of the block.
way	The way of the block.

Returns: The block.

Reimplemented from gem5::BaseTags.

Definition at line 189 of file fa_lru.cc.

References blks, and gem5::ArmISA::set.

◆ findVictim()

CacheBlk * gem5::FALRU::findVictim	(	Addr	addr,
		const bool	is_secure,
		const std::size_t	size,
		std::vector< CacheBlk * > &	evict_blks,
		const uint64_t	partition_id = 0 )

overridevirtual

Find replacement victim based on address.

The list of evicted blocks only contains the victim.

Parameters

addr	Address to find a victim for.
is_secure	True if the target memory space is secure.
size	Size, in bits, of new block to allocate.
evict_blks	Cache blocks to be evicted.
partition_id	Partition ID for resource management.

Returns: Cache block to be replaced.

Implements gem5::BaseTags.

Definition at line 196 of file fa_lru.cc.

References tail.

◆ insertBlock()

void gem5::FALRU::insertBlock	(	const PacketPtr	pkt,
		CacheBlk *	blk )

overridevirtual

Insert the new block into the cache and update replacement data.

Parameters

pkt	Packet holding the address to update
blk	The block to update.

Reimplemented from gem5::BaseTags.

Definition at line 210 of file fa_lru.cc.

References gem5::CacheEntry::getTag(), gem5::FALRUBlk::inCachesMask, gem5::BaseTags::insertBlock(), gem5::TaggedEntry::isSecure(), moveToHead(), gem5::BaseTags::stats, tagHash, and gem5::BaseTags::BaseTagStats::tagsInUse.

◆ invalidate()

void gem5::FALRU::invalidate ( CacheBlk * blk )

overridevirtual

Invalidate a cache block.

Parameters

blk	The block to invalidate.

Reimplemented from gem5::BaseTags.

Definition at line 117 of file fa_lru.cc.

References gem5::CacheEntry::getTag(), gem5::BaseTags::invalidate(), gem5::TaggedEntry::isSecure(), moveToTail(), gem5::BaseTags::stats, tagHash, and gem5::BaseTags::BaseTagStats::tagsInUse.

◆ moveBlock()

void gem5::FALRU::moveBlock	(	CacheBlk *	src_blk,
		CacheBlk *	dest_blk )

overridevirtual

Move a block's metadata to another location decided by the replacement policy.

It behaves as a swap, however, since the destination block should be invalid, the result is a move.

Parameters

src_blk	The source block.
dest_blk	The destination block. Must be invalid.

Reimplemented from gem5::BaseTags.

Definition at line 231 of file fa_lru.cc.

References panic.

◆ moveToHead()

void gem5::FALRU::moveToHead ( FALRUBlk * blk )

protected

Move a cache block to the MRU position.

Parameters

blk	The block to promote.

Definition at line 237 of file fa_lru.cc.

References cacheTracking, gem5::FALRU::CacheTracking::check(), head, gem5::FALRU::CacheTracking::moveBlockToHead(), gem5::FALRUBlk::next, gem5::FALRUBlk::prev, and tail.

Referenced by accessBlock(), and insertBlock().

◆ moveToTail()

void gem5::FALRU::moveToTail ( FALRUBlk * blk )

protected

Move a cache block to the LRU position.

Parameters

blk	The block to demote.

Definition at line 264 of file fa_lru.cc.

References cacheTracking, gem5::FALRU::CacheTracking::check(), head, gem5::FALRU::CacheTracking::moveBlockToTail(), gem5::FALRUBlk::next, gem5::FALRUBlk::prev, and tail.

Referenced by invalidate().

◆ regenerateBlkAddr()

Addr gem5::FALRU::regenerateBlkAddr ( const CacheBlk * blk ) const

inlineoverridevirtual

Regenerate the block address from the tag.

Parameters

block The block.

Returns: the block address.

Implements gem5::BaseTags.

Definition at line 255 of file fa_lru.hh.

References gem5::CacheEntry::getTag().

◆ tagsInit()

void gem5::FALRU::tagsInit ( )

overridevirtual

Initialize blocks as FALRUBlk instances.

Implements gem5::BaseTags.

Definition at line 90 of file fa_lru.cc.

References blks, gem5::BaseTags::blkSize, cacheTracking, gem5::CacheBlk::data, gem5::BaseTags::dataBlks, head, gem5::ArmISA::i, gem5::FALRU::CacheTracking::init(), gem5::FALRUBlk::next, gem5::BaseTags::numBlocks, gem5::FALRUBlk::prev, gem5::ReplaceableEntry::setPosition(), and tail.

Member Data Documentation

◆ blks

FALRUBlk* gem5::FALRU::blks

protected

The cache blocks.

Definition at line 119 of file fa_lru.hh.

Referenced by anyBlk(), FALRU(), findBlockBySetAndWay(), tagsInit(), and ~FALRU().

◆ cacheTracking

CacheTracking gem5::FALRU::cacheTracking

private

Definition at line 369 of file fa_lru.hh.

Referenced by accessBlock(), moveToHead(), moveToTail(), and tagsInit().

◆ head

FALRUBlk* gem5::FALRU::head

protected

The MRU block.

Definition at line 122 of file fa_lru.hh.

Referenced by gem5::FALRU::CacheTracking::check(), gem5::FALRU::CacheTracking::init(), moveToHead(), moveToTail(), and tagsInit().

◆ tagHash

TagHash gem5::FALRU::tagHash

protected

The address hash table.

Definition at line 139 of file fa_lru.hh.

Referenced by findBlock(), insertBlock(), and invalidate().

◆ tail

FALRUBlk* gem5::FALRU::tail

protected

The LRU block.

Definition at line 124 of file fa_lru.hh.

Referenced by gem5::FALRU::CacheTracking::check(), findVictim(), gem5::FALRU::CacheTracking::init(), moveToHead(), moveToTail(), and tagsInit().

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

mem/cache/tags/fa_lru.hh
mem/cache/tags/fa_lru.cc

Classes

Public Types

Public Member Functions

Protected Types

Protected Member Functions

Protected Attributes

Private Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ BlkType

◆ Params

◆ TagHash

◆ TagHashKey

Constructor & Destructor Documentation

◆ FALRU()

◆ ~FALRU()

Member Function Documentation

◆ accessBlock() [1/2]

◆ accessBlock() [2/2]

◆ anyBlk()

◆ extractTag()

◆ findBlock()

◆ findBlockBySetAndWay()

◆ findVictim()

◆ insertBlock()

◆ invalidate()

◆ moveBlock()

◆ moveToHead()

◆ moveToTail()

◆ regenerateBlkAddr()

◆ tagsInit()

Member Data Documentation

◆ blks

◆ cacheTracking

◆ head

◆ tagHash

◆ tail