gem5  v22.0.0.1
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gem5::compression::BaseDelta< BaseType, DeltaSizeBits > Class Template Reference

Base class for all base-delta-immediate compressors. More...

#include <base_delta.hh>

Inheritance diagram for gem5::compression::BaseDelta< BaseType, DeltaSizeBits >:
gem5::compression::DictionaryCompressor< BaseType > gem5::compression::BaseDictionaryCompressor gem5::compression::Base gem5::SimObject gem5::EventManager gem5::Serializable gem5::Drainable gem5::statistics::Group gem5::Named

Classes

class  PatternM
 
class  PatternX
 

Public Types

typedef BaseDictionaryCompressorParams Params
 
- Public Types inherited from gem5::compression::DictionaryCompressor< BaseType >
typedef BaseDictionaryCompressorParams Params
 
- Public Types inherited from gem5::compression::BaseDictionaryCompressor
typedef BaseDictionaryCompressorParams Params
 
- Public Types inherited from gem5::compression::Base
typedef BaseCacheCompressorParams Params
 
- Public Types inherited from gem5::SimObject
typedef SimObjectParams Params
 

Public Member Functions

 BaseDelta (const Params &p)
 
 ~BaseDelta ()=default
 
- Public Member Functions inherited from gem5::compression::DictionaryCompressor< BaseType >
 DictionaryCompressor (const Params &p)
 
 ~DictionaryCompressor ()=default
 
- Public Member Functions inherited from gem5::compression::BaseDictionaryCompressor
 BaseDictionaryCompressor (const Params &p)
 
 ~BaseDictionaryCompressor ()=default
 
- Public Member Functions inherited from gem5::compression::Base
 Base (const Params &p)
 
virtual ~Base ()=default
 
virtual void setCache (BaseCache *_cache)
 The cache can only be set once. More...
 
std::unique_ptr< CompressionDatacompress (const uint64_t *data, Cycles &comp_lat, Cycles &decomp_lat)
 Apply the compression process to the cache line. More...
 
Cycles getDecompressionLatency (const CacheBlk *blk)
 Get the decompression latency if the block is compressed. 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
 

Protected Types

enum  PatternNumber { X, M, NUM_PATTERNS }
 The patterns proposed in the paper. More...
 
using DictionaryEntry = typename DictionaryCompressor< BaseType >::DictionaryEntry
 
using PatternFactory = typename DictionaryCompressor< BaseType >::template Factory< PatternM, PatternX >
 Convenience factory declaration. More...
 
- Protected Types inherited from gem5::compression::DictionaryCompressor< BaseType >
typedef std::array< uint8_t, sizeof(BaseType)> DictionaryEntry
 Convenience typedef for a dictionary entry. More...
 
- Protected Types inherited from gem5::compression::Base
typedef uint64_t Chunk
 A chunk is a basic lexical unit. More...
 

Protected Member Functions

uint64_t getNumPatterns () const override
 Trick function to get the number of patterns. More...
 
std::unique_ptr< typename DictionaryCompressor< BaseType >::Pattern > getPattern (const DictionaryEntry &bytes, const DictionaryEntry &dict_bytes, const int match_location) const override
 
std::string getName (int number) const override
 Get meta-name assigned to the given pattern. More...
 
void resetDictionary () override
 Clear all dictionary entries. More...
 
void addToDictionary (DictionaryEntry data) override
 
std::unique_ptr< Base::CompressionDatacompress (const std::vector< Base::Chunk > &chunks, Cycles &comp_lat, Cycles &decomp_lat) override
 Apply the compression process to the cache line. More...
 
- Protected Member Functions inherited from gem5::compression::DictionaryCompressor< BaseType >
virtual std::unique_ptr< Pattern > getPattern (const DictionaryEntry &bytes, const DictionaryEntry &dict_bytes, const int match_location) const=0
 Since the factory cannot be instantiated here, classes that inherit from this base class have to implement the call to their factory's getPattern. More...
 
std::unique_ptr< Pattern > compressValue (const BaseType data)
 Compress data. More...
 
BaseType decompressValue (const Pattern *pattern)
 Decompress a pattern into a value that fits in a dictionary entry. More...
 
virtual void addToDictionary (const DictionaryEntry data)=0
 Add an entry to the dictionary. More...
 
virtual std::unique_ptr< DictionaryCompressor::CompDatainstantiateDictionaryCompData () const
 Instantiate a compression data of the sub-class compressor. More...
 
std::unique_ptr< Base::CompressionDatacompress (const std::vector< Chunk > &chunks)
 Apply compression. More...
 
std::unique_ptr< Base::CompressionDatacompress (const std::vector< Chunk > &chunks, Cycles &comp_lat, Cycles &decomp_lat) override
 Apply the compression process to the cache line. More...
 
void decompress (const CompressionData *comp_data, uint64_t *data) override
 Apply the decompression process to the compressed data. More...
 
- Protected Member Functions inherited from gem5::compression::Base
std::vector< ChunktoChunks (const uint64_t *data) const
 This function splits the raw data into chunks, so that it can be parsed by the compressor. More...
 
void fromChunks (const std::vector< Chunk > &chunks, uint64_t *data) const
 This function re-joins the chunks to recreate the original data. 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...
 

Static Protected Attributes

static constexpr int DEFAULT_MAX_NUM_BASES = 2
 

Additional Inherited Members

- Static Public Member Functions inherited from gem5::compression::Base
static void setDecompressionLatency (CacheBlk *blk, const Cycles lat)
 Set the decompression latency of compressed block. More...
 
static void setSizeBits (CacheBlk *blk, const std::size_t size_bits)
 Set the size of the compressed block, in bits. More...
 
- 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...
 
- Static Protected Member Functions inherited from gem5::compression::DictionaryCompressor< BaseType >
static DictionaryEntry toDictionaryEntry (BaseType value)
 Turn a value into a dictionary entry. More...
 
static BaseType fromDictionaryEntry (const DictionaryEntry &entry)
 Turn a dictionary entry into a value. More...
 
- Protected Attributes inherited from gem5::compression::DictionaryCompressor< BaseType >
std::vector< DictionaryEntrydictionary
 The dictionary. More...
 
- Protected Attributes inherited from gem5::compression::BaseDictionaryCompressor
const std::size_t dictionarySize
 Dictionary size. More...
 
std::size_t numEntries
 Number of valid entries in the dictionary. More...
 
gem5::compression::BaseDictionaryCompressor::DictionaryStats dictionaryStats
 
- Protected Attributes inherited from gem5::compression::Base
const std::size_t blkSize
 Uncompressed cache line size (in bytes). More...
 
const unsigned chunkSizeBits
 Chunk size, in number of bits. More...
 
const std::size_t sizeThreshold
 Size in bytes at which a compression is classified as bad and therefore the compressed block is restored to its uncompressed format. More...
 
const Cycles compChunksPerCycle
 Degree of parallelization of the compression process. More...
 
const Cycles compExtraLatency
 Extra latency added to compression due to packaging, shifting or other operations. More...
 
const Cycles decompChunksPerCycle
 Degree of parallelization of the decompression process. More...
 
const Cycles decompExtraLatency
 Extra latency added to decompression due to packaging, shifting or other operations. More...
 
BaseCachecache
 Pointer to the parent cache. More...
 
gem5::compression::Base::BaseStats stats
 
- 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

template<class BaseType, std::size_t DeltaSizeBits>
class gem5::compression::BaseDelta< BaseType, DeltaSizeBits >

Base class for all base-delta-immediate compressors.

Although not proposed like this in the original paper, the sub-compressors of BDI are dictionary based with 2 possible patterns: no match, where a dictionary entry must be allocated, and masked delta match with a dictionary entry, where the delta must be stored instead. The maximum number of dictionary entries is 2, and one of them is reserved for a zero base if using immediate compression.

Template Parameters
BaseTypeType of a base (dictionary) entry.

Definition at line 70 of file base_delta.hh.

Member Typedef Documentation

◆ DictionaryEntry

template<class BaseType , std::size_t DeltaSizeBits>
using gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::DictionaryEntry = typename DictionaryCompressor<BaseType>::DictionaryEntry
protected

Definition at line 76 of file base_delta.hh.

◆ Params

template<class BaseType , std::size_t DeltaSizeBits>
typedef BaseDictionaryCompressorParams gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::Params

Definition at line 129 of file base_delta.hh.

◆ PatternFactory

template<class BaseType , std::size_t DeltaSizeBits>
using gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::PatternFactory = typename DictionaryCompressor<BaseType>::template Factory<PatternM, PatternX>
protected

Convenience factory declaration.

The templates must be organized by size, with the smallest first, and "no-match" last.

Definition at line 100 of file base_delta.hh.

Member Enumeration Documentation

◆ PatternNumber

template<class BaseType , std::size_t DeltaSizeBits>
enum gem5::compression::BaseDelta::PatternNumber
protected

The patterns proposed in the paper.

Each letter represents a byte: Z is a null byte, M is a dictionary match, X is a new value. These are used as indexes to reference the pattern data. If a new pattern is added, it must be done before NUM_PATTERNS.

Enumerator
NUM_PATTERNS 

Definition at line 88 of file base_delta.hh.

Constructor & Destructor Documentation

◆ BaseDelta()

template<class BaseType , std::size_t DeltaSizeBits>
gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::BaseDelta ( const Params p)

Definition at line 48 of file base_delta_impl.hh.

◆ ~BaseDelta()

template<class BaseType , std::size_t DeltaSizeBits>
gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::~BaseDelta ( )
default

Member Function Documentation

◆ addToDictionary()

template<class BaseType , std::size_t DeltaSizeBits>
void gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::addToDictionary ( DictionaryEntry  data)
overrideprotected

Definition at line 65 of file base_delta_impl.hh.

◆ compress()

template<class BaseType , std::size_t DeltaSizeBits>
std::unique_ptr< Base::CompressionData > gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::compress ( const std::vector< Base::Chunk > &  chunks,
Cycles comp_lat,
Cycles decomp_lat 
)
overrideprotectedvirtual

Apply the compression process to the cache line.

Returns the number of cycles used by the compressor, however it is usually covered by a good pipelined execution, and is currently ignored. The decompression latency is also returned, in order to avoid increasing simulation time and memory consumption.

Parameters
chunksThe cache line to be compressed, divided into chunks.
comp_latCompression latency in number of cycles.
decomp_latDecompression latency in number of cycles.
Returns
Cache line after compression.

Implements gem5::compression::Base.

Definition at line 75 of file base_delta_impl.hh.

◆ getName()

template<class BaseType , std::size_t DeltaSizeBits>
std::string gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::getName ( int  number) const
inlineoverrideprotectedvirtual

Get meta-name assigned to the given pattern.

Parameters
numberThe number of the pattern.
Returns
The meta-name of the pattern.

Implements gem5::compression::BaseDictionaryCompressor.

Definition at line 111 of file base_delta.hh.

◆ getNumPatterns()

template<class BaseType , std::size_t DeltaSizeBits>
uint64_t gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::getNumPatterns ( ) const
inlineoverrideprotectedvirtual

Trick function to get the number of patterns.

Returns
The number of defined patterns.

Implements gem5::compression::BaseDictionaryCompressor.

Definition at line 93 of file base_delta.hh.

◆ getPattern()

template<class BaseType , std::size_t DeltaSizeBits>
std::unique_ptr<typename DictionaryCompressor<BaseType>::Pattern> gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::getPattern ( const DictionaryEntry bytes,
const DictionaryEntry dict_bytes,
const int  match_location 
) const
inlineoverrideprotected

Definition at line 103 of file base_delta.hh.

◆ resetDictionary()

template<class BaseType , std::size_t DeltaSizeBits>
void gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::resetDictionary
overrideprotectedvirtual

Clear all dictionary entries.

Reimplemented from gem5::compression::DictionaryCompressor< BaseType >.

Definition at line 55 of file base_delta_impl.hh.

Member Data Documentation

◆ DEFAULT_MAX_NUM_BASES

template<class BaseType , std::size_t DeltaSizeBits>
constexpr int gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::DEFAULT_MAX_NUM_BASES = 2
staticconstexprprotected

Definition at line 73 of file base_delta.hh.


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

Generated on Sat Jun 18 2022 08:13:40 for gem5 by doxygen 1.8.17