The elastic data memory request generator to read protobuf trace containing execution trace annotated with data and ordering dependencies. More...

#include <trace_cpu.hh>

Classes
struct	ElasticDataGenStatGroup

class	GraphNode
	The struct GraphNode stores an instruction in the trace file. More...

class	HardwareResource
	The HardwareResource class models structures that hold the in-flight nodes. More...

class	InputStream
	The InputStream encapsulates a trace file and the internal buffers and populates GraphNodes based on the input. More...

struct	ReadyNode
	Struct to store a ready-to-execute node and its execution tick. More...

Public Member Functions
	ElasticDataGen (TraceCPU &_owner, const std::string &_name, RequestPort &_port, RequestorID requestor_id, const std::string &trace_file, const TraceCPUParams &params)

Tick	init ()
	Called from TraceCPU init().

void	adjustInitTraceOffset (Tick &offset)
	Adjust traceOffset based on what TraceCPU init() determines on comparing the offsets in the fetch request and elastic traces.

const std::string &	name () const
	Returns name of the ElasticDataGen instance.

void	exit ()
	Exit the ElasticDataGen.

bool	readNextWindow ()
	Reads a line of the trace file.

template<typename T >
void	addDepsOnParent (GraphNode *new_node, T &dep_list)
	Iterate over the dependencies of a new node and add the new node to the list of dependents of the parent node.

void	execute ()
	This is the main execute function which consumes nodes from the sorted readyList.

PacketPtr	executeMemReq (GraphNode *node_ptr)
	Creates a new request for a load or store assigning the request parameters.

void	addToSortedReadyList (NodeSeqNum seq_num, Tick exec_tick)
	Add a ready node to the readyList.

void	printReadyList ()
	Print readyList for debugging using debug flag TraceCPUData.

void	completeMemAccess (PacketPtr pkt)
	When a load writeback is received, that is when the load completes, release the dependents on it.

bool	isExecComplete () const
	Returns the execComplete variable which is set when the last node is executed.

bool	checkAndIssue (const GraphNode *node_ptr, bool first=true)
	Attempts to issue a node once the node's source dependencies are complete.

uint64_t	getMicroOpCount () const
	Get number of micro-ops modelled in the TraceCPU replay.

Protected Attributes
gem5::TraceCPU::ElasticDataGen::ElasticDataGenStatGroup	elasticStats

Private Types
typedef uint64_t	NodeSeqNum
	Node sequence number type.

typedef uint64_t	NodeRobNum
	Node ROB number type.

typedef ProtoMessage::InstDepRecord::RecordType	RecordType

typedef ProtoMessage::InstDepRecord	Record

Private Attributes
TraceCPU &	owner
	Reference of the TraceCPU.

RequestPort &	port
	Reference of the port to be used to issue memory requests.

const RequestorID	requestorId
	RequestorID used for the requests being sent.

InputStream	trace
	Input stream used for reading the input trace file.

std::string	genName
	String to store the name of the FixedRetryGen.

PacketPtr	retryPkt
	PacketPtr used to store the packet to retry.

bool	traceComplete
	Set to true when end of trace is reached.

bool	nextRead
	Set to true when the next window of instructions need to be read.

bool	execComplete
	Set true when execution of trace is complete.

const uint32_t	windowSize
	Window size within which to check for dependencies.

HardwareResource	hwResource
	Hardware resources required to contain in-flight nodes and to throttle issuing of new nodes when resources are not available.

std::unordered_map< NodeSeqNum, GraphNode * >	depGraph
	Store the depGraph of GraphNodes.

std::queue< const GraphNode * >	depFreeQueue
	Queue of dependency-free nodes that are pending issue because resources are not available.

std::list< ReadyNode >	readyList
	List of nodes that are ready to execute.

Detailed Description

The elastic data memory request generator to read protobuf trace containing execution trace annotated with data and ordering dependencies.

It deduces the time at which to send a load/store request by tracking the dependencies. It attempts to send a memory request for a load/store without performing real execution of micro-ops. If L1 cache port sends packet succesfully, the generator checks which instructions became dependency free as a result of this and schedules an event accordingly. If it fails to send the packet, it waits for a retry from the cache.

Definition at line 524 of file trace_cpu.hh.

Member Typedef Documentation

◆ NodeRobNum

typedef uint64_t gem5::TraceCPU::ElasticDataGen::NodeRobNum

private

Node ROB number type.

Definition at line 531 of file trace_cpu.hh.

◆ NodeSeqNum

typedef uint64_t gem5::TraceCPU::ElasticDataGen::NodeSeqNum

private

Node sequence number type.

Definition at line 528 of file trace_cpu.hh.

◆ Record

typedef ProtoMessage::InstDepRecord gem5::TraceCPU::ElasticDataGen::Record

private

Definition at line 534 of file trace_cpu.hh.

◆ RecordType

typedef ProtoMessage::InstDepRecord::RecordType gem5::TraceCPU::ElasticDataGen::RecordType

private

Definition at line 533 of file trace_cpu.hh.

Constructor & Destructor Documentation

◆ ElasticDataGen()

gem5::TraceCPU::ElasticDataGen::ElasticDataGen	(	TraceCPU &	_owner,
		const std::string &	_name,
		RequestPort &	_port,
		RequestorID	requestor_id,
		const std::string &	trace_file,
		const TraceCPUParams &	params )

inline

Definition at line 805 of file trace_cpu.hh.

References DPRINTF, and windowSize.

Member Function Documentation

◆ addDepsOnParent()

template<typename T >

void gem5::TraceCPU::ElasticDataGen::addDepsOnParent	(	GraphNode *	new_node,
		T &	dep_list )

Iterate over the dependencies of a new node and add the new node to the list of dependents of the parent node.

Parameters

new_node new node to add to the graph

Template Parameters

dep_list the dependency list of type rob or register, that is to be iterated, and may get modified

Definition at line 344 of file trace_cpu.cc.

References depGraph, elasticStats, gem5::TraceCPU::ElasticDataGen::ElasticDataGenStatGroup::maxDependents, and gem5::statistics::ScalarBase< Derived, Stor >::value().

Referenced by readNextWindow().

◆ addToSortedReadyList()

void gem5::TraceCPU::ElasticDataGen::addToSortedReadyList	(	NodeSeqNum	seq_num,
		Tick	exec_tick )

Add a ready node to the readyList.

When inserting, ensure the nodes are sorted in ascending order of their execute ticks.

Parameters

seq_num	seq. num of ready node
exec_tick	the execute tick of the ready node

Definition at line 748 of file trace_cpu.cc.

References elasticStats, gem5::TraceCPU::ElasticDataGen::ReadyNode::execTick, gem5::TraceCPU::ElasticDataGen::ElasticDataGenStatGroup::maxReadyListSize, readyList, gem5::Packet::req, retryPkt, gem5::TraceCPU::ElasticDataGen::ReadyNode::seqNum, and gem5::statistics::ScalarBase< Derived, Stor >::value().

Referenced by checkAndIssue().

◆ adjustInitTraceOffset()

void gem5::TraceCPU::ElasticDataGen::adjustInitTraceOffset ( Tick & offset )

Adjust traceOffset based on what TraceCPU init() determines on comparing the offsets in the fetch request and elastic traces.

Parameters

trace_offset trace offset set by comparing both traces

Definition at line 277 of file trace_cpu.cc.

References gem5::ArmISA::offset, and readyList.

Referenced by gem5::TraceCPU::init().

◆ checkAndIssue()

bool gem5::TraceCPU::ElasticDataGen::checkAndIssue	(	const GraphNode *	node_ptr,
		bool	first = true )

Attempts to issue a node once the node's source dependencies are complete.

If resources are available then add it to the readyList, otherwise the node is not issued and is stored in depFreeQueue until resources become available.

Parameters

node_ptr	pointer to node to be issued
first	true if this is the first attempt to issue this node

Returns: true if node was added to readyList

Definition at line 641 of file trace_cpu.cc.

Referenced by completeMemAccess(), execute(), and readNextWindow().

◆ completeMemAccess()

void gem5::TraceCPU::ElasticDataGen::completeMemAccess ( PacketPtr pkt )

When a load writeback is received, that is when the load completes, release the dependents on it.

This is called from the dcache port recvTimingResp().

Definition at line 681 of file trace_cpu.cc.

References checkAndIssue(), gem5::Clocked::clockEdge(), gem5::TraceCPU::ElasticDataGen::GraphNode::dependents, depGraph, DPRINTF, hwResource, gem5::Packet::isWrite(), nextRead, owner, printReadyList(), readyList, gem5::TraceCPU::ElasticDataGen::HardwareResource::release(), gem5::TraceCPU::ElasticDataGen::HardwareResource::releaseStoreBuffer(), gem5::Packet::req, retryPkt, gem5::TraceCPU::ElasticDataGen::GraphNode::robNum, gem5::TraceCPU::schedDcacheNextEvent(), gem5::TraceCPU::ElasticDataGen::GraphNode::seqNum, traceComplete, gem5::TraceCPU::updateNumOps(), and windowSize.

Referenced by gem5::TraceCPU::dcacheRecvTimingResp().

◆ execute()

void gem5::TraceCPU::ElasticDataGen::execute ( )

This is the main execute function which consumes nodes from the sorted readyList.

First attempt to issue the pending dependency-free nodes held in the depFreeQueue. Insert the ready-to-issue nodes into the readyList. Then iterate through the readyList and when a node has its execute tick equal to curTick(), execute it. If the node is a load or a store call executeMemReq() and if it is neither, simply mark it complete.

Definition at line 369 of file trace_cpu.cc.

Referenced by gem5::TraceCPU::schedDcacheNext().

◆ executeMemReq()

PacketPtr gem5::TraceCPU::ElasticDataGen::executeMemReq ( GraphNode * node_ptr )

Creates a new request for a load or store assigning the request parameters.

Calls the port's sendTimingReq() and returns a packet if the send failed so that it can be saved for a retry.

Parameters

node_ptr pointer to the load or store node to be executed

Returns: packet pointer if the request failed and nullptr if it was sent successfully

Definition at line 565 of file trace_cpu.cc.

Referenced by execute().

◆ exit()

void gem5::TraceCPU::ElasticDataGen::exit ( )

Exit the ElasticDataGen.

Definition at line 285 of file trace_cpu.cc.

References gem5::TraceCPU::ElasticDataGen::InputStream::reset(), and trace.

◆ getMicroOpCount()

uint64_t gem5::TraceCPU::ElasticDataGen::getMicroOpCount ( ) const

inline

Get number of micro-ops modelled in the TraceCPU replay.

Definition at line 931 of file trace_cpu.hh.

References gem5::TraceCPU::ElasticDataGen::InputStream::getMicroOpCount(), and trace.

◆ init()

Tick gem5::TraceCPU::ElasticDataGen::init ( )

Called from TraceCPU init().

Reads the first message from the input trace file and returns the send tick.

Returns: Tick when first packet must be sent

Definition at line 246 of file trace_cpu.cc.

References depGraph, DPRINTF, panic_if, printReadyList(), readNextWindow(), readyList, and windowSize.

Referenced by gem5::TraceCPU::init().

◆ isExecComplete()

bool gem5::TraceCPU::ElasticDataGen::isExecComplete ( ) const

inline

Returns the execComplete variable which is set when the last node is executed.

Returns: bool true if execComplete is set, false otherwise.

Definition at line 916 of file trace_cpu.hh.

References execComplete.

Referenced by gem5::TraceCPU::schedDcacheNext().

◆ name()

const std::string & gem5::TraceCPU::ElasticDataGen::name ( ) const

inline

Returns name of the ElasticDataGen instance.

Definition at line 843 of file trace_cpu.hh.

References genName.

◆ printReadyList()

void gem5::TraceCPU::ElasticDataGen::printReadyList ( )

Print readyList for debugging using debug flag TraceCPUData.

Definition at line 808 of file trace_cpu.cc.

References depGraph, DPRINTF, DPRINTFR, readyList, and gem5::TraceCPU::ElasticDataGen::GraphNode::typeToStr().

Referenced by completeMemAccess(), execute(), and init().

◆ readNextWindow()

bool gem5::TraceCPU::ElasticDataGen::readNextWindow ( )

Reads a line of the trace file.

Returns the tick when the next request should be generated. If the end of the file has been reached, it returns false.

Returns: bool false if end of file has been reached else true

Definition at line 291 of file trace_cpu.cc.

References addDepsOnParent(), checkAndIssue(), depGraph, DPRINTF, gem5::TraceCPU::ElasticDataGen::InputStream::read(), gem5::TraceCPU::ElasticDataGen::GraphNode::regDep, gem5::TraceCPU::ElasticDataGen::GraphNode::robDep, gem5::TraceCPU::ElasticDataGen::GraphNode::seqNum, trace, traceComplete, and windowSize.

Referenced by execute(), and init().

Member Data Documentation

◆ depFreeQueue

std::queue<const GraphNode*> gem5::TraceCPU::ElasticDataGen::depFreeQueue

private

Queue of dependency-free nodes that are pending issue because resources are not available.

This is chosen to be FIFO so that dependent nodes which become free in program order get pushed into the queue in that order. Thus nodes are more likely to issue in program order.

Definition at line 988 of file trace_cpu.hh.

Referenced by checkAndIssue(), and execute().

◆ depGraph

std::unordered_map<NodeSeqNum, GraphNode*> gem5::TraceCPU::ElasticDataGen::depGraph

private

Store the depGraph of GraphNodes.

Definition at line 979 of file trace_cpu.hh.

Referenced by addDepsOnParent(), completeMemAccess(), execute(), init(), printReadyList(), and readNextWindow().

◆ elasticStats

gem5::TraceCPU::ElasticDataGen::ElasticDataGenStatGroup gem5::TraceCPU::ElasticDataGen::elasticStats

protected

Referenced by addDepsOnParent(), addToSortedReadyList(), execute(), and executeMemReq().

◆ execComplete

bool gem5::TraceCPU::ElasticDataGen::execComplete

private

Set true when execution of trace is complete.

Definition at line 959 of file trace_cpu.hh.

Referenced by execute(), and isExecComplete().

◆ genName

std::string gem5::TraceCPU::ElasticDataGen::genName

private

String to store the name of the FixedRetryGen.

Definition at line 947 of file trace_cpu.hh.

Referenced by name().

◆ hwResource

HardwareResource gem5::TraceCPU::ElasticDataGen::hwResource

private

Hardware resources required to contain in-flight nodes and to throttle issuing of new nodes when resources are not available.

Definition at line 976 of file trace_cpu.hh.

Referenced by checkAndIssue(), completeMemAccess(), and execute().

◆ nextRead

bool gem5::TraceCPU::ElasticDataGen::nextRead

private

Set to true when the next window of instructions need to be read.

Definition at line 956 of file trace_cpu.hh.

Referenced by completeMemAccess(), and execute().

◆ owner

TraceCPU& gem5::TraceCPU::ElasticDataGen::owner

private

Reference of the TraceCPU.

Definition at line 935 of file trace_cpu.hh.

Referenced by checkAndIssue(), completeMemAccess(), execute(), and executeMemReq().

◆ port

RequestPort& gem5::TraceCPU::ElasticDataGen::port

private

Reference of the port to be used to issue memory requests.

Definition at line 938 of file trace_cpu.hh.

Referenced by execute(), and executeMemReq().

◆ readyList

std::list<ReadyNode> gem5::TraceCPU::ElasticDataGen::readyList

private

List of nodes that are ready to execute.

Definition at line 991 of file trace_cpu.hh.

Referenced by addToSortedReadyList(), adjustInitTraceOffset(), completeMemAccess(), execute(), init(), and printReadyList().

◆ requestorId

const RequestorID gem5::TraceCPU::ElasticDataGen::requestorId

private

RequestorID used for the requests being sent.

Definition at line 941 of file trace_cpu.hh.

Referenced by executeMemReq().

◆ retryPkt

PacketPtr gem5::TraceCPU::ElasticDataGen::retryPkt

private

PacketPtr used to store the packet to retry.

Definition at line 950 of file trace_cpu.hh.

Referenced by addToSortedReadyList(), completeMemAccess(), and execute().

◆ trace

InputStream gem5::TraceCPU::ElasticDataGen::trace

private

Input stream used for reading the input trace file.

Definition at line 944 of file trace_cpu.hh.

Referenced by exit(), getMicroOpCount(), gem5::TraceCPU::ElasticDataGen::InputStream::read(), readNextWindow(), and gem5::TraceCPU::ElasticDataGen::InputStream::reset().

◆ traceComplete

bool gem5::TraceCPU::ElasticDataGen::traceComplete

private

Set to true when end of trace is reached.

Definition at line 953 of file trace_cpu.hh.

Referenced by completeMemAccess(), execute(), and readNextWindow().

◆ windowSize

const uint32_t gem5::TraceCPU::ElasticDataGen::windowSize

private

Window size within which to check for dependencies.

Its value is made equal to the window size used to generate the trace which is recorded in the trace header. The dependency graph must be populated enough such that when a node completes, its potential child node must be found and the dependency removed before the completed node itself is removed. Thus as soon as the graph shrinks to become smaller than this window, we read in the next window.

Definition at line 970 of file trace_cpu.hh.

Referenced by completeMemAccess(), ElasticDataGen(), execute(), init(), and readNextWindow().

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

cpu/trace/trace_cpu.hh
cpu/trace/trace_cpu.cc

Classes

Public Member Functions

Protected Attributes

Private Types

Private Attributes

Detailed Description

Member Typedef Documentation

◆ NodeRobNum

◆ NodeSeqNum

◆ Record

◆ RecordType

Constructor & Destructor Documentation

◆ ElasticDataGen()

Member Function Documentation

◆ addDepsOnParent()

◆ addToSortedReadyList()

◆ adjustInitTraceOffset()

◆ checkAndIssue()

◆ completeMemAccess()

◆ execute()

◆ executeMemReq()

◆ exit()

◆ getMicroOpCount()

◆ init()

◆ isExecComplete()

◆ name()

◆ printReadyList()

◆ readNextWindow()

Member Data Documentation

◆ depFreeQueue

◆ depGraph

◆ elasticStats

◆ execComplete

◆ genName

◆ hwResource

◆ nextRead

◆ owner

◆ port

◆ readyList

◆ requestorId

◆ retryPkt

◆ trace

◆ traceComplete

◆ windowSize