poputil::TensorUseTracker Class Reference

Class that tracks the usage of data on different tiles. More...

#include <TileMapping.hpp>

Public Types
enum class	MappingMethod { OptimizeHaloRegions , ConstrainMappingToUsedTiles , None }

Public Member Functions
	TensorUseTracker (unsigned numTiles, unsigned startTile=0, bool ascendingMappingOrder=true)
	Constructor for the TensorUseTracker class. More...
	TensorUseTracker (const TensorUseTracker &other)
	Constructor for the TensorUseTracker class.
	TensorUseTracker (TensorUseTracker &&other)
	Default constructor for the TensorUseTracker class.
TensorUseTracker &	operator= (const TensorUseTracker &other)
	Assignment operator for the TensorUseTracker class.
TensorUseTracker &	operator= (TensorUseTracker &&other)
	Default assignment operator for the TensorUseTracker class.
	~TensorUseTracker ()
	Destructor for the TensorUserTracker class.
void	add (const poplar::Graph &graph, unsigned tile, const poplar::Tensor &t)
	Add a case of data usage. More...
void	add (TensorUseTracker other)
	Add cases of data usage from another tracker. More...
void	resolve (const poplar::Graph &graph, unsigned grainSize, unsigned minElementsPerTile, bool extendPartialUsage=false, TensorUseTracker::MappingMethod mappingMethod=TensorUseTracker::MappingMethod::None)
	Resolve data usage for mapping. More...
void	mapTensorsByUse (poplar::Graph &graph, unsigned grainSize, unsigned minElementsPerTile, bool extendPartialUsage=false, TensorUseTracker::MappingMethod mappingMethod=TensorUseTracker::MappingMethod::None)
	Map data according to use. More...
bool	empty () const
	Check if any cases of data usage have been registered. More...

Detailed Description

Class that tracks the usage of data on different tiles.

If data is broadcast to many tiles, it is sometimes efficient to map the data so that it is spread evenly amongst the tiles that use it.

This class can collect information about the use of data and then calculate a suitable tile mapping.

Member Enumeration Documentation

MappingMethod

enum class poputil::TensorUseTracker::MappingMethod

strong

Enumerator
OptimizeHaloRegions	Map "halo regions" to single tiles. These are regions that are used by multiple tiles but have neighbouring regions used by subsets of those tiles.
ConstrainMappingToUsedTiles	Mapping of elements is constrained to be only on tiles that use them. Otherwise, to meet grain size constraints, elements may be mapped to tiles which do not use them.
None	No mapping method used.

Constructor & Destructor Documentation

TensorUseTracker()

poputil::TensorUseTracker::TensorUseTracker	(	unsigned	numTiles,
		unsigned	startTile = 0,
		bool	ascendingMappingOrder = true
	)

Constructor for the TensorUseTracker class.

Parameters

numTiles	The number of tiles to track data use of.
startTile	The tile to start tracking data use on.
ascendingMappingOrder	If true, the first tile used = startTile and tiles are allocated in increasing order. If false, the first tile used = (number of device tiles -1 startTile) and tiles are allocated in decreasing order.

Member Function Documentation

add() [1/2]

void poputil::TensorUseTracker::add	(	const poplar::Graph &	graph,
		unsigned	tile,
		const poplar::Tensor &	t
	)

Add a case of data usage.

Parameters

graph	The Poplar graph being tracked.
tile	The tile that the use occurs on.
t	The tensor representing the data being used.

add() [2/2]

void poputil::TensorUseTracker::add

(

TensorUseTracker

other

)

Add cases of data usage from another tracker.

Parameters

other

The TensorUseTracker to merge data usage information from.

empty()

bool poputil::TensorUseTracker::empty

(

)

const

Check if any cases of data usage have been registered.

Returns

If true, no cases have been registered. If false, cases have been registered.

mapTensorsByUse()

void poputil::TensorUseTracker::mapTensorsByUse	(	poplar::Graph &	graph,
		unsigned	grainSize,
		unsigned	minElementsPerTile,
		bool	extendPartialUsage = false,
		TensorUseTracker::MappingMethod	mappingMethod = TensorUseTracker::MappingMethod::None
	)

Map data according to use.

This function will set the tile mapping of variable regions based on tracked data use. Variable regions with usage on multiple tiles will have their elements spread across those tiles.

Parameters

graph	The Poplar graph being tracked.
grainSize	The number of elements mapped to each tile will be an integer multiple of the grain size.
minElementsPerTile	The minimum number of elements that must be mapped to a tile.
extendPartialUsage	When set, partial use of tensors will be extended to cover the entire tensor, based on the usage of neighbouring regions before mapping.
mappingMethod	Method used for mapping elements.

resolve()

void poputil::TensorUseTracker::resolve	(	const poplar::Graph &	graph,
		unsigned	grainSize,
		unsigned	minElementsPerTile,
		bool	extendPartialUsage = false,
		TensorUseTracker::MappingMethod	mappingMethod = TensorUseTracker::MappingMethod::None
	)

Resolve data usage for mapping.

Data used on multiple tiles will have their usage spread across those tiles.

Parameters

graph	The Poplar graph being tracked.
grainSize	The number of elements mapped to each tile will be an integer multiple of the grain size.
minElementsPerTile	The minimum number of elements that must be mapped to a tile.
extendPartialUsage	When set, partial usage of tensors will be extended to cover the entire tensor, based on the usage of neighbouring regions.
mappingMethod	Method used for mapping elements.

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

• include/poputil/TileMapping.hpp