gem5  v21.1.0.2
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gem5::prefetch::AccessMapPatternMatching Class Reference

#include <access_map_pattern_matching.hh>

Inheritance diagram for gem5::prefetch::AccessMapPatternMatching:
gem5::ClockedObject gem5::SimObject gem5::Clocked gem5::EventManager gem5::Serializable gem5::Drainable gem5::statistics::Group gem5::Named

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. More...
 
void calculatePrefetch (const Base::PrefetchInfo &pfi, std::vector< Queued::AddrPriority > &addresses)
 
- Public Member Functions inherited from gem5::ClockedObject
 ClockedObject (const ClockedObjectParams &p)
 
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::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...
 
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
 
- Public Member Functions inherited from gem5::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 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. More...
 
AccessMapEntrygetAccessMapEntry (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. More...
 
void setEntryState (AccessMapEntry &entry, Addr block, enum AccessMapState state)
 Updates the state of a block within an AccessMapEntry, also updates the prefetcher metrics. More...
 
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. More...
 

Private Attributes

const unsigned blkSize
 Cacheline size used by the prefetcher using this object. More...
 
const unsigned limitStride
 Limit the stride checking to -limitStride/+limitStride. More...
 
const unsigned startDegree
 Maximum number of prefetch generated. More...
 
const uint64_t hotZoneSize
 Amount of memory covered by a hot zone. More...
 
const double highCoverageThreshold
 A prefetch coverage factor bigger than this is considered high. More...
 
const double lowCoverageThreshold
 A prefetch coverage factor smaller than this is considered low. More...
 
const double highAccuracyThreshold
 A prefetch accuracy factor bigger than this is considered high. More...
 
const double lowAccuracyThreshold
 A prefetch accuracy factor smaller than this is considered low. More...
 
const double highCacheHitThreshold
 A cache hit ratio bigger than this is considered high. More...
 
const double lowCacheHitThreshold
 A cache hit ratio smaller than this is considered low. More...
 
const Cycles epochCycles
 Cycles in an epoch period. More...
 
const Tick offChipMemoryLatency
 Off chip memory latency to use for the epoch bandwidth calculation. More...
 
AssociativeSet< AccessMapEntryaccessMapTable
 Access map table. More...
 
uint64_t numGoodPrefetches
 Number of good prefetches. More...
 
uint64_t numTotalPrefetches
 Number of prefetches issued. More...
 
uint64_t numRawCacheMisses
 Number of raw cache misses. More...
 
uint64_t numRawCacheHits
 Number of raw cache hits. More...
 
unsigned degree
 Current degree. More...
 
unsigned usefulDegree
 Current useful degree. More...
 
EventFunctionWrapper epochEvent
 

Additional Inherited Members

- Public Types inherited from gem5::ClockedObject
using Params = ClockedObjectParams
 Parameters of ClockedObject. More...
 
- 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. 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...
 
- Public Attributes inherited from gem5::ClockedObject
PowerStatepowerState
 
- 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 Member Functions inherited from gem5::Clocked
 Clocked (ClockDomain &clk_domain)
 Create a clocked object and set the clock domain based on the parameters. More...
 
 Clocked (Clocked &)=delete
 
Clockedoperator= (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 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 56 of file access_map_pattern_matching.hh.

Member Enumeration Documentation

◆ AccessMapState

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

Enumerator
AM_INIT 
AM_PREFETCH 
AM_ACCESS 
AM_INVALID 

Definition at line 84 of file access_map_pattern_matching.hh.

Constructor & Destructor Documentation

◆ AccessMapPatternMatching()

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

Definition at line 43 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 
)

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 159 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::SlimAMPM::calculatePrefetch(), and gem5::prefetch::AMPM::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
statesvector containing the states of three contiguous hot zones
currenttarget block (cacheline)
strideaccess stride to obtain the reference cachelines
Returns
true if current is a prefetch candidate

Definition at line 149 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_addraddress of the hot zone
is_securewhether the address belongs to the secure memory area
Returns
the corresponding entry

Definition at line 108 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 74 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
entryAccessMapEntry to update
blockcacheline within the hot zone
statenew state

Definition at line 124 of file access_map_pattern_matching.cc.

References AM_ACCESS, AM_INIT, AM_PREFETCH, numGoodPrefetches, numRawCacheHits, numRawCacheMisses, numTotalPrefetches, panic, 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 68 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 113 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 59 of file access_map_pattern_matching.hh.

Referenced by calculatePrefetch().

◆ degree

unsigned gem5::prefetch::AccessMapPatternMatching::degree
private

Current degree.

Definition at line 136 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 79 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent(), and startup().

◆ epochEvent

EventFunctionWrapper gem5::prefetch::AccessMapPatternMatching::epochEvent
private

Definition at line 186 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 71 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 75 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 67 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 65 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 61 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 73 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 77 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 69 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 119 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 134 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 129 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 124 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 81 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 63 of file access_map_pattern_matching.hh.

◆ usefulDegree

unsigned gem5::prefetch::AccessMapPatternMatching::usefulDegree
private

Current useful degree.

Definition at line 138 of file access_map_pattern_matching.hh.

Referenced by processEpochEvent().


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

Generated on Tue Sep 21 2021 12:31:50 for gem5 by doxygen 1.8.17