gem5  v22.0.0.2
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gem5::replacement_policy::TreePLRU Class Reference

#include <tree_plru_rp.hh>

Inheritance diagram for gem5::replacement_policy::TreePLRU:
gem5::replacement_policy::Base gem5::SimObject gem5::EventManager gem5::Serializable gem5::Drainable gem5::statistics::Group gem5::Named

Classes

struct  TreePLRUReplData
 Tree-PLRU-specific implementation of replacement data. More...
 

Public Types

typedef TreePLRURPParams Params
 
- Public Types inherited from gem5::replacement_policy::Base
typedef BaseReplacementPolicyParams Params
 
- Public Types inherited from gem5::SimObject
typedef SimObjectParams Params
 

Public Member Functions

 TreePLRU (const Params &p)
 
 ~TreePLRU ()=default
 
void invalidate (const std::shared_ptr< ReplacementData > &replacement_data) override
 Invalidate replacement data to set it as the next probable victim. More...
 
void touch (const std::shared_ptr< ReplacementData > &replacement_data) const override
 Touch an entry to update its replacement data. More...
 
void reset (const std::shared_ptr< ReplacementData > &replacement_data) const override
 Reset replacement data. More...
 
ReplaceableEntrygetVictim (const ReplacementCandidates &candidates) const override
 Find replacement victim using TreePLRU bits. More...
 
std::shared_ptr< ReplacementDatainstantiateEntry () override
 Instantiate a replacement data entry. More...
 
- Public Member Functions inherited from gem5::replacement_policy::Base
 Base (const Params &p)
 
virtual ~Base ()=default
 
virtual void touch (const std::shared_ptr< ReplacementData > &replacement_data, const PacketPtr pkt)
 Update replacement data. More...
 
virtual void reset (const std::shared_ptr< ReplacementData > &replacement_data, const PacketPtr pkt)
 Reset replacement data. More...
 
- Public Member Functions inherited from gem5::SimObject
const Paramsparams () 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. 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...
 
virtual void regProbeListeners ()
 Register probe listeners for this object. More...
 
ProbeManagergetProbeManager ()
 Get the probe manager for this object. More...
 
virtual PortgetPort (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 gem5::EventManager
EventQueueeventQueue () 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 gem5::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 gem5::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 gem5::statistics::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 (statistics::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 InforesolveStat (std::string name) const
 Resolve a stat by its name within this group. More...
 
void mergeStatGroup (Group *block)
 Merge the contents (stats & children) of a block to this block. More...
 
 Group ()=delete
 
 Group (const Group &)=delete
 
Groupoperator= (const Group &)=delete
 
- Public Member Functions inherited from gem5::Named
 Named (const std::string &name_)
 
virtual ~Named ()=default
 
virtual std::string name () const
 

Private Types

typedef std::vector< bool > PLRUTree
 Instead of implementing the tree itself with pointers, it is implemented as an array of bits. More...
 

Private Attributes

const uint64_t numLeaves
 Number of leaves that share a single replacement data. More...
 
uint64_t count
 Count of the number of sharers of a replacement data. More...
 
PLRUTreetreeInstance
 Holds the latest temporary tree instance created by instantiateEntry(). More...
 

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. More...
 
static SimObjectfind (const char *name)
 Find the SimObject with the given name and return a pointer to it. More...
 
static void setSimObjectResolver (SimObjectResolver *resolver)
 There is a single object name resolver, and it is only set when simulation is restoring from checkpoints. More...
 
static SimObjectResolvergetSimObjectResolver ()
 There is a single object name resolver, and it is only set when simulation is restoring from checkpoints. More...
 
- Static Public Member Functions inherited from gem5::Serializable
static const std::string & currentSection ()
 Gets the fully-qualified name of the active section. More...
 
static void generateCheckpointOut (const std::string &cpt_dir, std::ofstream &outstream)
 Generate a checkpoint file so that the serialization can be routed to it. More...
 
- Protected Member Functions inherited from gem5::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 Attributes inherited from gem5::SimObject
const SimObjectParams & _params
 Cached copy of the object parameters. More...
 
- Protected Attributes inherited from gem5::EventManager
EventQueueeventq
 A pointer to this object's event queue. More...
 

Detailed Description

Definition at line 87 of file tree_plru_rp.hh.

Member Typedef Documentation

◆ Params

Definition at line 159 of file tree_plru_rp.hh.

◆ PLRUTree

Instead of implementing the tree itself with pointers, it is implemented as an array of bits.

The index of the node defines its position in the tree, and its parent. Index 0 represents the root, 1 is its left node, and 2 is its right node. Then, in a BFS fashion this is expanded to the following nodes (3 and 4 are respectively 1's left and right nodes, and 5 and 6 are 2's left and right nodes, and so on).

i.e., the following trees are equivalent in this representation: ____1____ 0 1 0 1 1 0 A B C D E F G H

1 0 1 0 1 1 0

Notice that the replacement data entries are not represented in the tree to avoid unnecessary storage costs.

Definition at line 109 of file tree_plru_rp.hh.

Constructor & Destructor Documentation

◆ TreePLRU()

gem5::replacement_policy::TreePLRU::TreePLRU ( const Params p)

Definition at line 105 of file tree_plru_rp.cc.

References fatal_if, gem5::isPowerOf2(), and numLeaves.

◆ ~TreePLRU()

gem5::replacement_policy::TreePLRU::~TreePLRU ( )
default

Member Function Documentation

◆ getVictim()

ReplaceableEntry * gem5::replacement_policy::TreePLRU::getVictim ( const ReplacementCandidates candidates) const
overridevirtual

Find replacement victim using TreePLRU bits.

It is assumed that all candidates share the same replacement data tree.

Parameters
candidatesReplacement candidates, selected by indexing policy.
Returns
Replacement entry to be replaced.

Implements gem5::replacement_policy::Base.

Definition at line 172 of file tree_plru_rp.cc.

References gem5::replacement_policy::leftSubtreeIndex(), numLeaves, and gem5::replacement_policy::rightSubtreeIndex().

◆ instantiateEntry()

std::shared_ptr< ReplacementData > gem5::replacement_policy::TreePLRU::instantiateEntry ( )
overridevirtual

Instantiate a replacement data entry.

Consecutive calls to this function use the same tree up to numLeaves. When numLeaves replacement data have been created, a new tree is generated, and the counter is reset. Therefore, it is essential that entries that share the same replacement data call this function consecutively.

Returns
A shared pointer to the new replacement data.

Implements gem5::replacement_policy::Base.

Definition at line 200 of file tree_plru_rp.cc.

References count, numLeaves, and treeInstance.

◆ invalidate()

void gem5::replacement_policy::TreePLRU::invalidate ( const std::shared_ptr< ReplacementData > &  replacement_data)
overridevirtual

Invalidate replacement data to set it as the next probable victim.

Makes tree leaf of replacement data the LRU (tree bits point to it).

Parameters
replacement_dataReplacement data to be invalidated.

Implements gem5::replacement_policy::Base.

Definition at line 113 of file tree_plru_rp.cc.

References gem5::replacement_policy::isRightSubtree(), and gem5::replacement_policy::parentIndex().

◆ reset()

void gem5::replacement_policy::TreePLRU::reset ( const std::shared_ptr< ReplacementData > &  replacement_data) const
overridevirtual

Reset replacement data.

Used when an entry is inserted. Provides the same functionality as touch().

Parameters
replacement_dataReplacement data to be reset.

Implements gem5::replacement_policy::Base.

Definition at line 164 of file tree_plru_rp.cc.

References touch().

◆ touch()

void gem5::replacement_policy::TreePLRU::touch ( const std::shared_ptr< ReplacementData > &  replacement_data) const
overridevirtual

Touch an entry to update its replacement data.

Makes tree leaf of replacement data the MRU.

Parameters
replacement_dataReplacement data to be touched.

Implements gem5::replacement_policy::Base.

Definition at line 138 of file tree_plru_rp.cc.

References gem5::replacement_policy::isRightSubtree(), and gem5::replacement_policy::parentIndex().

Referenced by reset().

Member Data Documentation

◆ count

uint64_t gem5::replacement_policy::TreePLRU::count
private

Count of the number of sharers of a replacement data.

It is used when instantiating entries to share a replacement data among many replaceable entries.

Definition at line 121 of file tree_plru_rp.hh.

Referenced by instantiateEntry().

◆ numLeaves

const uint64_t gem5::replacement_policy::TreePLRU::numLeaves
private

Number of leaves that share a single replacement data.

Definition at line 114 of file tree_plru_rp.hh.

Referenced by getVictim(), instantiateEntry(), and TreePLRU().

◆ treeInstance

PLRUTree* gem5::replacement_policy::TreePLRU::treeInstance
private

Holds the latest temporary tree instance created by instantiateEntry().

Definition at line 126 of file tree_plru_rp.hh.

Referenced by instantiateEntry().


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

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