Flash Device model The Flash Device model is a timing model for a NAND flash device. More...

#include <flash_device.hh>

Inheritance diagram for FlashDevice:

Classes
struct	CallBackEntry

struct	FlashDeviceStats

struct	PageMapEntry
	Every logical address maps to a physical block and a physical page. More...

Public Member Functions
	FlashDevice (const FlashDeviceParams *)
	Initialize functions. More...

	~FlashDevice ()

DrainState	drain () override
	Checkpoint functions. More...

void	checkDrain ()
	Checkdrain; needed to enable checkpoints. More...

void	serialize (CheckpointOut &cp) const override
	Serialize; needed to create checkpoints. More...

void	unserialize (CheckpointIn &cp) override
	Unserialize; needed to restore from checkpoints. More...

Public Member Functions inherited from AbstractNVM
	AbstractNVM (const AbstractNVMParams *p)

virtual	~AbstractNVM ()

Public Member Functions inherited from SimObject
const Params *	params () const

	SimObject (const Params *_params)

virtual	~SimObject ()

virtual const std::string	name () const

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	resetStats ()
	Reset statistics associated with this object. More...

virtual void	regProbePoints ()
	Register probe points for this object. More...

virtual void	regProbeListeners ()
	Register probe listeners for this object. More...

ProbeManager *	getProbeManager ()
	Get the probe manager for this object. 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 EventManager
	EventManager (EventManager &em)

	EventManager (EventManager *em)

	EventManager (EventQueue *eq)

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)

void	setCurTick (Tick newVal)

Public Member Functions inherited from 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 Drainable
DrainState	drainState () const
	Return the current drain state of an object. More...

virtual void	notifyFork ()
	Notify a child process of a fork. More...

Private Types
enum	Actions { ActionRead, ActionWrite, ActionErase, ActionCopy }
	Defines the possible actions to the flash. More...

Private Member Functions
void	initializeMemory (uint64_t disk_size, uint32_t sector_size) override
	Device access functions Inherrited from AbstractNVM. More...

void	readMemory (uint64_t address, uint32_t amount, Callback *event) override
	Access functions Access function to simulate a read/write access to the memory. More...

void	writeMemory (uint64_t address, uint32_t amount, Callback *event) override

void	initializeFlash (uint64_t disk_size, uint32_t sector_size)
	Initialization function; called when all disk specifics are known. More...

void	accessDevice (uint64_t address, uint32_t amount, Callback *event, Actions action)
	Flash action function. More...

void	actionComplete ()
	Event rescheduler. More...

Tick	remap (uint64_t logic_page_addr)
	FTL functionality. More...

Tick	accessTimes (uint64_t address, Actions accesstype)
	Access time calculator. More...

void	clearUnknownPages (uint32_t index)
	Function to indicate that a page is known. More...

bool	getUnknownPages (uint32_t index)
	Function to test if a page is known. More...

void	regStats () override
	Stats register function. More...

Private Attributes
uint64_t	diskSize
	Disk sizes in bytes. More...

const uint32_t	blockSize

const uint32_t	pageSize

const uint32_t	GCActivePercentage
	Garbage collection algorithm emulator. More...

const Tick	readLatency
	Access latencies. More...

const Tick	writeLatency

const Tick	eraseLatency

const Enums::DataDistribution	dataDistribution
	Flash organization. More...

const uint32_t	numPlanes

struct FlashDeviceStats	stats
	RequestHandler stats. More...

uint32_t	pagesPerBlock
	Disk dimensions in pages and blocks. More...

uint32_t	pagesPerDisk

uint32_t	blocksPerDisk

uint32_t	planeMask

std::vector< uint32_t >	unknownPages
	when the disk is first started we are unsure of the number of used pages, this variable will help determining what we do know. More...

std::vector< struct PageMapEntry >	locationTable
	address to logic place has a block and a page field More...

std::vector< uint32_t >	blockValidEntries
	number of valid entries per block More...

std::vector< uint32_t >	blockEmptyEntries
	number of empty entries More...

std::vector< std::deque < struct CallBackEntry > >	planeEventQueue
	This vector of queues keeps track of all the callbacks per plane. More...

EventWrapper< FlashDevice,&FlashDevice::actionComplete >	planeEvent
	Completion event. More...

Additional Inherited Members
Public Types inherited from SimObject
typedef SimObjectParams	Params

Static Public Member Functions inherited from SimObject
static void	serializeAll (CheckpointOut &cp)
	Serialize all SimObjects in the system. More...

static SimObject *	find (const char *name)
	Find the SimObject with the given name and return a pointer to it. More...

Static Public Member Functions inherited from Serializable
static const std::string &	currentSection ()
	Get the fully-qualified name of the active section. More...

static void	serializeAll (const std::string &cpt_dir)

static void	unserializeGlobals (CheckpointIn &cp)

Static Public Attributes inherited from Serializable
static int	ckptCount = 0

static int	ckptMaxCount = 0

static int	ckptPrevCount = -1

Protected Member Functions inherited from 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 SimObject
const SimObjectParams *	_params
	Cached copy of the object parameters. More...

Protected Attributes inherited from EventManager
EventQueue *	eventq
	A pointer to this object's event queue. More...

Detailed Description

Flash Device model The Flash Device model is a timing model for a NAND flash device.

It doesn't tranfer any data

Definition at line 56 of file flash_device.hh.

Member Enumeration Documentation

enum FlashDevice::Actions

private

Defines the possible actions to the flash.

Enumerator
ActionRead
ActionWrite
ActionErase
ActionCopy	A copy involves taking all the used pages from a block and store it in another.

Definition at line 73 of file flash_device.hh.

Constructor & Destructor Documentation

FlashDevice::FlashDevice ( const FlashDeviceParams * p )

Initialize functions.

Flash Device constructor and destructor.

Definition at line 75 of file flash_device.cc.

References fatal, numPlanes, and planeMask.

FlashDevice::~FlashDevice ( )

Definition at line 154 of file flash_device.cc.

References DPRINTF.

Member Function Documentation

void FlashDevice::accessDevice	(	uint64_t	address,
		uint32_t	amount,
		Callback *	event,
		Actions	action
	)

private

Flash action function.

Handles the accesses to the device.

The function determines when certain actions are scheduled and schedules an event that uses the callback function on completion of the action.

The access will be broken up in a number of page accesses. The number of page accesses depends on the amount that needs to be transfered. The assumption here is that the interface is completely ignorant of the page size and that this model has to figure out all of the transaction characteristics.

Check if the page is known and used. unknownPages is a bitmap of all the pages. It tracks wether we can be sure that the information of this page is taken into acount in the model (is it considered in blockValidEntries and blockEmptyEntries?). If it has been used in the past, then it is known.

previous part of the function found the times spend in different planes, now lets find the maximum to know when to callback the disk

If there are no events for this plane, then add the current time to the occupation time; otherwise, plan it after the last event. If by chance that event is handled in this tick, then we would still end up with the same result.

Definition at line 165 of file flash_device.cc.

References accessTimes(), ActionRead, ActionWrite, blockEmptyEntries, blockValidEntries, clearUnknownPages(), X86ISA::count, curTick(), DPRINTF, MipsISA::event, FlashDevice::FlashDeviceStats::fileSystemAccess, FlashDevice::CallBackEntry::function, getUnknownPages(), MipsISA::index, locationTable, numPlanes, pageSize, pagesPerBlock, planeEvent, planeEventQueue, planeMask, FlashDevice::FlashDeviceStats::readAccess, FlashDevice::FlashDeviceStats::readLatency, remap(), EventManager::reschedule(), Stats::DistBase< Derived, Stor >::sample(), EventManager::schedule(), Event::scheduled(), X86ISA::size(), stats, FlashDevice::CallBackEntry::time, Event::when(), FlashDevice::FlashDeviceStats::writeAccess, and FlashDevice::FlashDeviceStats::writeLatency.

Referenced by readMemory(), and writeMemory().

Tick FlashDevice::accessTimes	(	uint64_t	address,
		Actions	accesstype
	)

private

Access time calculator.

Calculates the accesstime per operation needed.

Just read the page

Write the page, and read the result

Erase and check wether it was successfull

Copy every valid page

Definition at line 406 of file flash_device.cc.

References ActionCopy, ActionErase, ActionRead, ActionWrite, blockValidEntries, DPRINTF, eraseLatency, readLatency, and writeLatency.

Referenced by accessDevice(), and remap().

void FlashDevice::actionComplete ( )

private

Event rescheduler.

When a plane completes its action, this event is triggered.

When a callback function was associated with that event, it will be called.

Search for a callback that is supposed to happen in this Tick

Invariant: All queued events are scheduled in the present or future.

To ensure that the follow-up action is executed correctly, the callback entry first need to be cleared before it can be called.

Found a callback, lets make it happen

Find when to schedule the planeEvent next

Schedule the next plane that will be ready (if any)

Definition at line 291 of file flash_device.cc.

References checkDrain(), curTick(), DPRINTF, numPlanes, planeEvent, planeEventQueue, Callback::process(), EventManager::reschedule(), and Event::when().

void FlashDevice::checkDrain ( )

Checkdrain; needed to enable checkpoints.

Definition at line 586 of file flash_device.cc.

References curTick(), DPRINTF, Draining, Drainable::drainState(), planeEvent, Drainable::signalDrainDone(), and Event::when().

Referenced by actionComplete().

void FlashDevice::clearUnknownPages ( uint32_t index )

inlineprivate

Function to indicate that a page is known.

clearUnknownPages.

defines that a page is known and used unknownPages is a bitmap of all the pages. It tracks wether we can be sure that the information of this page is taken into acount in the model (is it considered in blockValidEntries and blockEmptyEntries?). If it has been used in the past, then it is known. But it needs to be tracked to make decisions about write accesses, and indirectly about copy actions. one unknownPage entry is a 32 bit integer. So if we have a page index, then that means that we need entry floor(index/32) (index >> 5) and we need to select the bit which number is equal to the remainder of index/32 (index%32). The bit is cleared to make sure that we see it as considered in the future.

Definition at line 456 of file flash_device.cc.

References unknownPages.

Referenced by accessDevice().

DrainState FlashDevice::drain ( )

overridevirtual

Checkpoint functions.

Drain; needed to enable checkpoints.

Implements Drainable.

Definition at line 570 of file flash_device.cc.

References DPRINTF, Drained, Draining, planeEvent, and Event::scheduled().

bool FlashDevice::getUnknownPages ( uint32_t index )

inlineprivate

Function to test if a page is known.

getUnknownPages.

Verify wether a page is known

Definition at line 467 of file flash_device.cc.

References unknownPages.

Referenced by accessDevice().

void FlashDevice::initializeFlash	(	uint64_t	disk_size,
		uint32_t	sector_size
	)

private

Initialization function; called when all disk specifics are known.

Initiates all the flash functions: initializes the lookup tables, age of the device, etc.

This can only be done once the disk image is known. Thats why it can't be done in the constructor.

Sanity information: check flash configuration

Garbage collection related

This is a bitmap. Every bit is a page unknownPages is a vector of 32 bit integers. If every page was an integer, the total size would be pagesPerDisk; since we can map one page per bit we need ceil(pagesPerDisk/32) entries. 32 = 1 << 5 hence it will do to just shift pagesPerDisk five positions and add one. This will allocate one integer to many for this data structure in the worst case.

Definition at line 112 of file flash_device.cc.

References blockEmptyEntries, blockSize, blocksPerDisk, blockValidEntries, X86ISA::count, dataDistribution, diskSize, DPRINTF, locationTable, pageSize, pagesPerBlock, pagesPerDisk, and unknownPages.

Referenced by initializeMemory().

void FlashDevice::initializeMemory	(	uint64_t	disk_size,
		uint32_t	sector_size
	)

inlineoverrideprivatevirtual

Device access functions Inherrited from AbstractNVM.

Implements AbstractNVM.

Definition at line 110 of file flash_device.hh.

References initializeFlash().

void FlashDevice::readMemory	(	uint64_t	address,
		uint32_t	amount,
		Callback *	event
	)

inlineoverrideprivatevirtual

Access functions Access function to simulate a read/write access to the memory.

Once the action has completed, the Callback event should be called. Putting a NULL pointer as callback is valid syntax, and should result in the simulation of the access, but with no callback to the higher layer. This may be used to occupy the device, such that next actions will be delayed. The read/write function will schedule the incoming requests on a first come first serve basis.

Parameters

address	The logical address to a location in the Non-volatile memory.
amount	The amount of data transfered from the NVM in bytes
event	A pointer to a callback function that will perform the actions taken by the disk controller on successfull completion of the data transfer between the disk and the disk controller.

Implements AbstractNVM.

Definition at line 115 of file flash_device.hh.

References accessDevice(), and ActionRead.

void FlashDevice::regStats ( )

overrideprivatevirtual

Stats register function.

Amount of GC activations

Histogram of address accesses

Histogram of access latencies

Reimplemented from SimObject.

Definition at line 473 of file flash_device.cc.

References Stats::DataWrap< Derived, InfoProxyType >::desc(), FlashDevice::FlashDeviceStats::fileSystemAccess, Stats::DataWrap< Derived, InfoProxyType >::flags(), Stats::Histogram::init(), SimObject::name(), Stats::DataWrap< Derived, InfoProxyType >::name(), Stats::none, Stats::pdf, FlashDevice::FlashDeviceStats::readAccess, FlashDevice::FlashDeviceStats::readLatency, SimObject::regStats(), stats, FlashDevice::FlashDeviceStats::totalGCActivations, FlashDevice::FlashDeviceStats::writeAccess, and FlashDevice::FlashDeviceStats::writeLatency.