gem5 v24.0.0.0
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#include <signature_path.hh>
Classes | |
struct | PatternEntry |
Pattern entry data type, a set of stride and counter entries. More... | |
struct | PatternStrideEntry |
A stride entry with its counter. More... | |
struct | SignatureEntry |
Signature entry data type. More... | |
Public Member Functions | |
SignaturePath (const SignaturePathPrefetcherParams &p) | |
~SignaturePath ()=default | |
void | calculatePrefetch (const PrefetchInfo &pfi, std::vector< AddrPriority > &addresses, const CacheAccessor &cache) override |
Public Member Functions inherited from gem5::prefetch::Queued | |
Queued (const QueuedPrefetcherParams &p) | |
virtual | ~Queued () |
void | notify (const CacheAccessProbeArg &acc, const PrefetchInfo &pfi) override |
Notify prefetcher of cache access (may be any access or just misses, depending on cache parameters.) | |
void | insert (const PacketPtr &pkt, PrefetchInfo &new_pfi, int32_t priority, const CacheAccessor &cache) |
PacketPtr | getPacket () override |
Tick | nextPrefetchReadyTime () const override |
void | printQueue (const std::list< DeferredPacket > &queue) const |
Public Member Functions inherited from gem5::prefetch::Base | |
Base (const BasePrefetcherParams &p) | |
virtual | ~Base ()=default |
virtual void | setParentInfo (System *sys, ProbeManager *pm, unsigned blk_size) |
virtual void | notifyFill (const CacheAccessProbeArg &acc) |
Notify prefetcher of cache fill. | |
virtual void | notifyEvict (const EvictionInfo &info) |
Notify prefetcher of cache eviction. | |
void | prefetchUnused () |
void | incrDemandMhsrMisses () |
void | pfHitInCache () |
void | pfHitInMSHR () |
void | pfHitInWB () |
void | regProbeListeners () override |
Register probe points for this object. | |
void | probeNotify (const CacheAccessProbeArg &acc, bool miss) |
Process a notification event from the ProbeListener. | |
void | addEventProbe (SimObject *obj, const char *name) |
Add a SimObject and a probe name to listen events from. | |
void | addMMU (BaseMMU *mmu) |
Add a BaseMMU object to be used whenever a translation is needed. | |
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. | |
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 uint16_t | signature_t |
Signature type. | |
typedef int16_t | stride_t |
Stride type. | |
Protected Types inherited from gem5::prefetch::Queued | |
using | const_iterator = std::list<DeferredPacket>::const_iterator |
using | iterator = std::list<DeferredPacket>::iterator |
Protected Member Functions | |
signature_t | updateSignature (signature_t sig, stride_t str) const |
Generates a new signature from an existing one and a new stride. | |
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. | |
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. | |
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. | |
void | updatePatternTable (Addr signature, stride_t stride) |
Updates the pattern table with the provided signature and stride. | |
virtual double | calculateLookaheadConfidence (PatternEntry const &sig, PatternStrideEntry const &lookahead) const |
Computes the lookahead path confidence of the provided pattern entry. | |
virtual double | calculatePrefetchConfidence (PatternEntry const &sig, PatternStrideEntry const &entry) const |
Computes the prefetch confidence of the provided pattern entry. | |
virtual void | increasePatternEntryCounter (PatternEntry &pattern_entry, PatternStrideEntry &pstride_entry) |
Increases the counter of a given PatternEntry/PatternStrideEntry. | |
virtual void | handleSignatureTableMiss (stride_t current_block, signature_t &new_signature, double &new_conf, stride_t &new_stride) |
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. | |
virtual void | auxiliaryPrefetcher (Addr ppn, stride_t current_block, bool is_secure, std::vector< AddrPriority > &addresses) |
Auxiliar prefetch mechanism used at the end of calculatePrefetch. | |
virtual void | handlePageCrossingLookahead (signature_t signature, stride_t last_offset, stride_t delta, double path_confidence) |
Handles the situation when the lookahead process has crossed the boundaries of the current page. | |
Protected Member Functions inherited from gem5::prefetch::Base | |
bool | observeAccess (const PacketPtr &pkt, bool miss, bool prefetched) const |
Determine if this access should be observed. | |
bool | samePage (Addr a, Addr b) const |
Determine if addresses are on the same page. | |
Addr | blockAddress (Addr a) const |
Determine the address of the block in which a lays. | |
Addr | blockIndex (Addr a) const |
Determine the address of a at block granularity. | |
Addr | pageAddress (Addr a) const |
Determine the address of the page in which a lays. | |
Addr | pageOffset (Addr a) const |
Determine the page-offset of a | |
Addr | pageIthBlockAddress (Addr page, uint32_t i) const |
Build the address of the i-th block inside the page. | |
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 | |
const unsigned | stridesPerPatternEntry |
Number of strides stored in each pattern entry. | |
const uint8_t | signatureShift |
Number of bits to shift when generating a new signature. | |
const signature_t | signatureBits |
Size of the signature, in bits. | |
const double | prefetchConfidenceThreshold |
Minimum confidence to issue a prefetch. | |
const double | lookaheadConfidenceThreshold |
Minimum confidence to keep navigating lookahead entries. | |
AssociativeSet< SignatureEntry > | signatureTable |
Signature table. | |
AssociativeCache< PatternEntry > | patternTable |
Pattern table. | |
Protected Attributes inherited from gem5::prefetch::Queued | |
std::list< DeferredPacket > | pfq |
std::list< DeferredPacket > | pfqMissingTranslation |
const unsigned | queueSize |
Maximum size of the prefetch queue. | |
const unsigned | missingTranslationQueueSize |
Maximum size of the queue holding prefetch requests with missing address translations. | |
const Cycles | latency |
Cycles after generation when a prefetch can first be issued. | |
const bool | queueSquash |
Squash queued prefetch if demand access observed. | |
const bool | queueFilter |
Filter prefetches if already queued. | |
const bool | cacheSnoop |
Snoop the cache before generating prefetch (cheating basically) | |
const bool | tagPrefetch |
Tag prefetch with PC of generating access? | |
const unsigned int | throttleControlPct |
Percentage of requests that can be throttled. | |
gem5::prefetch::Queued::QueuedStats | statsQueued |
Protected Attributes inherited from gem5::prefetch::Base | |
System * | system |
Pointer to the parent system. | |
ProbeManager * | probeManager |
Pointer to the parent cache's probe manager. | |
unsigned | blkSize |
The block size of the parent cache. | |
unsigned | lBlkSize |
log_2(block size of the parent cache). | |
const bool | onMiss |
Only consult prefetcher on cache misses? | |
const bool | onRead |
Consult prefetcher on reads? | |
const bool | onWrite |
Consult prefetcher on reads? | |
const bool | onData |
Consult prefetcher on data accesses? | |
const bool | onInst |
Consult prefetcher on instruction accesses? | |
const RequestorID | requestorId |
Request id for prefetches. | |
const Addr | pageBytes |
const bool | prefetchOnAccess |
Prefetch on every access, not just misses. | |
const bool | prefetchOnPfHit |
Prefetch on hit on prefetched lines. | |
const bool | useVirtualAddresses |
Use Virtual Addresses for prefetching. | |
gem5::prefetch::Base::StatGroup | prefetchStats |
uint64_t | issuedPrefetches |
Total prefetches issued. | |
uint64_t | usefulPrefetches |
Total prefetches that has been useful. | |
BaseMMU * | mmu |
Registered mmu for address translations. | |
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. | |
Additional Inherited Members | |
Public Types inherited from gem5::prefetch::Queued | |
using | AddrPriority = std::pair<Addr, int32_t> |
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 |
Definition at line 56 of file signature_path.hh.
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Signature type.
Definition at line 60 of file signature_path.hh.
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Stride type.
Definition at line 62 of file signature_path.hh.
gem5::prefetch::SignaturePath::SignaturePath | ( | const SignaturePathPrefetcherParams & | p | ) |
Definition at line 44 of file signature_path.cc.
References fatal_if, lookaheadConfidenceThreshold, and prefetchConfidenceThreshold.
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Generates an address to be prefetched.
ppn | page number to prefetch from |
last_block | last accessed block within the page ppn |
delta | difference, in number of blocks, from the last_block accessed to the block to prefetch. The block to prefetch is computed by this formula: ppn * pageBytes + (last_block + delta) * blkSize This value can be negative. |
path_confidence | the confidence factor of this prefetch |
signature | the current path signature |
is_secure | whether this page is inside the secure memory area |
addresses | addresses to prefetch will be added to this vector |
Definition at line 101 of file signature_path.cc.
References gem5::prefetch::Base::blkSize, DPRINTF, handlePageCrossingLookahead(), gem5::MaxAddr, gem5::prefetch::Base::pageBytes, and gem5::RiscvISA::ppn.
Referenced by auxiliaryPrefetcher(), and calculatePrefetch().
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Auxiliar prefetch mechanism used at the end of calculatePrefetch.
This prefetcher uses this to activate the next line prefetcher if no prefetch candidates have been found.
ppn | physical page number of the current accessed page |
current_block | last accessed block within the page ppn |
is_secure | whether this page is inside the secure memory area |
addresses | the addresses to be prefetched are added to this vector |
updated_filter_entries | set of addresses containing these that their filter has been updated, if this call updates a new entry |
Reimplemented in gem5::prefetch::SignaturePathV2.
Definition at line 318 of file signature_path.cc.
References addPrefetch(), and gem5::RiscvISA::ppn.
Referenced by calculatePrefetch().
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Computes the lookahead path confidence of the provided pattern entry.
sig | the PatternEntry to use |
lookahead | PatternStrideEntry within the provided PatternEntry |
maximum confidence is 0.95, guaranteeing that current confidence will eventually fall beyond the threshold
Reimplemented in gem5::prefetch::SignaturePathV2.
Definition at line 217 of file signature_path.cc.
References gem5::GenericSatCounter< T >::calcSaturation(), and gem5::prefetch::SignaturePath::PatternStrideEntry::counter.
Referenced by calculatePrefetch().
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Implements gem5::prefetch::Queued.
Definition at line 233 of file signature_path.cc.
References addPrefetch(), auxiliaryPrefetcher(), gem5::prefetch::Base::blkSize, calculateLookaheadConfidence(), calculatePrefetchConfidence(), gem5::prefetch::SignaturePath::PatternStrideEntry::counter, gem5::prefetch::Base::PrefetchInfo::getAddr(), getSignatureEntry(), gem5::prefetch::Base::PrefetchInfo::isSecure(), gem5::prefetch::SignaturePath::SignatureEntry::lastBlock, lookaheadConfidenceThreshold, gem5::prefetch::Base::pageBytes, patternTable, gem5::RiscvISA::ppn, prefetchConfidenceThreshold, gem5::prefetch::SignaturePath::SignatureEntry::signature, gem5::ArmISA::stride, gem5::prefetch::SignaturePath::PatternStrideEntry::stride, gem5::prefetch::SignaturePath::PatternEntry::strideEntries, updatePatternTable(), and updateSignature().
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Computes the prefetch confidence of the provided pattern entry.
sig | the PatternEntry to use |
entry | PatternStrideEntry within the provided PatternEntry |
Reimplemented in gem5::prefetch::SignaturePathV2.
Definition at line 210 of file signature_path.cc.
References gem5::GenericSatCounter< T >::calcSaturation(), and gem5::prefetch::SignaturePath::PatternStrideEntry::counter.
Referenced by calculatePrefetch().
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Obtains the PatternEntry of the given signature, if the signature is not found, it allocates a new one, replacing an existing entry if needed.
signature | the signature of the desired entry |
Definition at line 193 of file signature_path.cc.
References patternTable.
Referenced by updatePatternTable().
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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.
ppn | physical page number of the page |
is_secure | whether this page is inside the secure memory area |
block | accessed block within the page |
miss | if the entry is not found, this will be set to true |
stride | set to the computed stride |
initial_confidence | set to the initial confidence value |
Definition at line 168 of file signature_path.cc.
References handleSignatureTableMiss(), gem5::prefetch::SignaturePath::SignatureEntry::lastBlock, gem5::RiscvISA::ppn, gem5::prefetch::SignaturePath::SignatureEntry::signature, signatureTable, and gem5::ArmISA::stride.
Referenced by calculatePrefetch().
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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.
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 in gem5::prefetch::SignaturePathV2.
Definition at line 282 of file signature_path.hh.
Referenced by addPrefetch().
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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.
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 in gem5::prefetch::SignaturePathV2.
Definition at line 142 of file signature_path.cc.
Referenced by getSignatureEntry().
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Increases the counter of a given PatternEntry/PatternStrideEntry.
pattern_entry | the corresponding PatternEntry |
pstride_entry | the PatternStrideEntry within the PatternEntry |
Reimplemented in gem5::prefetch::SignaturePathV2.
Definition at line 151 of file signature_path.cc.
References gem5::prefetch::SignaturePath::PatternStrideEntry::counter.
Referenced by updatePatternTable().
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Updates the pattern table with the provided signature and stride.
signature | the signature to use to index the pattern table |
stride | the stride to use to index the set of strides of the pattern table entry |
Definition at line 158 of file signature_path.cc.
References getPatternEntry(), gem5::prefetch::SignaturePath::PatternEntry::getStrideEntry(), increasePatternEntryCounter(), and gem5::ArmISA::stride.
Referenced by calculatePrefetch().
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Generates a new signature from an existing one and a new stride.
sig | current signature |
str | stride to add to the new signature |
Definition at line 159 of file signature_path.hh.
References gem5::ArmISA::mask, signatureBits, and signatureShift.
Referenced by calculatePrefetch().
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Minimum confidence to keep navigating lookahead entries.
Definition at line 73 of file signature_path.hh.
Referenced by calculatePrefetch(), and SignaturePath().
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Pattern table.
Definition at line 151 of file signature_path.hh.
Referenced by calculatePrefetch(), and getPatternEntry().
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Minimum confidence to issue a prefetch.
Definition at line 71 of file signature_path.hh.
Referenced by calculatePrefetch(), and SignaturePath().
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Size of the signature, in bits.
Definition at line 69 of file signature_path.hh.
Referenced by updateSignature().
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Number of bits to shift when generating a new signature.
Definition at line 67 of file signature_path.hh.
Referenced by updateSignature().
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Signature table.
Definition at line 86 of file signature_path.hh.
Referenced by getSignatureEntry().
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Number of strides stored in each pattern entry.
Definition at line 65 of file signature_path.hh.