The BlockHistogram class provides collective methods for constructing block-wide histograms from data samples partitioned across a CUDA thread block. More...

Detailed Description

template<typename T, int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>
class cub::BlockHistogram< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, ALGORITHM, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >

The BlockHistogram class provides collective methods for constructing block-wide histograms from data samples partitioned across a CUDA thread block.

Template Parameters

T	The sample type being histogrammed (must be castable to an integer bin identifier)
BLOCK_DIM_X	The thread block length in threads along the X dimension
ITEMS_PER_THREAD	The number of items per thread
BINS	The number bins within the histogram
ALGORITHM	[optional] cub::BlockHistogramAlgorithm enumerator specifying the underlying algorithm to use (default: cub::BLOCK_HISTO_SORT)
BLOCK_DIM_Y	[optional] The thread block length in threads along the Y dimension (default: 1)
BLOCK_DIM_Z	[optional] The thread block length in threads along the Z dimension (default: 1)
PTX_ARCH	[optional] \ptxversion

Overview

A histogram counts the number of observations that fall into each of the disjoint categories (known as bins).
BlockHistogram can be optionally specialized to use different algorithms:
1. cub::BLOCK_HISTO_SORT. Sorting followed by differentiation. More...
2. cub::BLOCK_HISTO_ATOMIC. Use atomic addition to update byte counts directly. More...

Performance Considerations

\granularity

A Simple Example: \blockcollective{BlockHistogram}

: The code snippet below illustrates a 256-bin histogram of 512 integer samples that are partitioned across 128 threads where each thread owns 4 samples.

: #include <cub/cub.cuh> // or equivalently <cub/block/block_histogram.cuh>
__global__ void ExampleKernel(...)
{
// Specialize a 256-bin BlockHistogram type for a 1D block of 128 threads having 4 character samples each
typedef cub::BlockHistogram<unsigned char, 128, 4, 256> BlockHistogram;
// Allocate shared memory for BlockHistogram
__shared__ typename BlockHistogram::TempStorage temp_storage;
// Allocate shared memory for block-wide histogram bin counts
__shared__ unsigned int smem_histogram[256];
// Obtain input samples per thread
unsigned char data[4];
...
// Compute the block-wide histogram
BlockHistogram(temp_storage).Histogram(data, smem_histogram);

Performance and Usage Considerations

The histogram output can be constructed in shared or device-accessible memory
See cub::BlockHistogramAlgorithm for performance details regarding algorithmic alternatives

Definition at line 157 of file block_histogram.cuh.

Data Structures
struct	TempStorage
	\smemstorage{BlockHistogram} More...

Public Member Functions
Collective constructors
__device__ __forceinline__	BlockHistogram ()
	Collective constructor using a private static allocation of shared memory as temporary storage.

__device__ __forceinline__	BlockHistogram (TempStorage &temp_storage)
	Collective constructor using the specified memory allocation as temporary storage. More...

Histogram operations
template<typename CounterT >
__device__ __forceinline__ void	InitHistogram (CounterT histogram[BINS])
	Initialize the shared histogram counters to zero. More...

template<typename CounterT >
__device__ __forceinline__ void	Histogram (T(&items)[ITEMS_PER_THREAD], CounterT histogram[BINS])
	Constructs a block-wide histogram in shared/device-accessible memory. Each thread contributes an array of input elements. More...

template<typename CounterT >
__device__ __forceinline__ void	Composite (T(&items)[ITEMS_PER_THREAD], CounterT histogram[BINS])
	Updates an existing block-wide histogram in shared/device-accessible memory. Each thread composites an array of input elements. More...

Private Types
enum	{ BLOCK_THREADS = BLOCK_DIM_X * BLOCK_DIM_Y * BLOCK_DIM_Z }
	Constants. More...

typedef If<(SAFE_ALGORITHM==BLOCK_HISTO_SORT), BlockHistogramSort< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >, BlockHistogramAtomic< BINS > >::Type	InternalBlockHistogram
	Internal specialization.

typedef InternalBlockHistogram::TempStorage	_TempStorage
	Shared memory storage layout type for BlockHistogram.

Private Member Functions
__device__ __forceinline__ _TempStorage &	PrivateStorage ()
	Internal storage allocator.

Private Attributes
_TempStorage &	temp_storage
	Shared storage reference.

unsigned int	linear_tid
	Linear thread-id.

Static Private Attributes
static const BlockHistogramAlgorithm	SAFE_ALGORITHM

Member Enumeration Documentation

◆ anonymous enum

template<typename T , int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>

anonymous enum

private

Constants.

Enumerator
BLOCK_THREADS	The thread block size in threads.

Definition at line 166 of file block_histogram.cuh.

Constructor & Destructor Documentation

◆ BlockHistogram()

template<typename T , int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>

__device__ __forceinline__ cub::BlockHistogram< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, ALGORITHM, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >::BlockHistogram ( TempStorage & temp_storage )

inline

Collective constructor using the specified memory allocation as temporary storage.

Parameters

[in] temp_storage Reference to memory allocation having layout type TempStorage

Definition at line 239 of file block_histogram.cuh.

Member Function Documentation

◆ Composite()

template<typename T , int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>

template<typename CounterT >

__device__ __forceinline__ void cub::BlockHistogram< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, ALGORITHM, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >::Composite	(	T(&)	items[ITEMS_PER_THREAD],
		CounterT	histogram[BINS]
	)

inline

Updates an existing block-wide histogram in shared/device-accessible memory. Each thread composites an array of input elements.

\granularity
\smemreuse

Snippet: The code snippet below illustrates a the initialization and update of a histogram of 512 integer samples that are partitioned across 128 threads where each thread owns 4 samples.

: #include <cub/cub.cuh> // or equivalently <cub/block/block_histogram.cuh>
__global__ void ExampleKernel(...)
{
// Specialize a 256-bin BlockHistogram type for a 1D block of 128 threads having 4 character samples each
typedef cub::BlockHistogram<unsigned char, 128, 4, 256> BlockHistogram;
// Allocate shared memory for BlockHistogram
__shared__ typename BlockHistogram::TempStorage temp_storage;
// Allocate shared memory for block-wide histogram bin counts
__shared__ unsigned int smem_histogram[256];
// Obtain input samples per thread
unsigned char thread_samples[4];
...
// Initialize the block-wide histogram
BlockHistogram(temp_storage).InitHistogram(smem_histogram);
// Update the block-wide histogram
BlockHistogram(temp_storage).Composite(thread_samples, smem_histogram);

Template Parameters

CounterT [inferred] Histogram counter type

Parameters

[in]	items	Calling thread's input values to histogram
[out]	histogram	Reference to shared/device-accessible memory histogram

Definition at line 404 of file block_histogram.cuh.

◆ Histogram()

template<typename T , int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>

template<typename CounterT >

__device__ __forceinline__ void cub::BlockHistogram< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, ALGORITHM, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >::Histogram	(	T(&)	items[ITEMS_PER_THREAD],
		CounterT	histogram[BINS]
	)

inline

Constructs a block-wide histogram in shared/device-accessible memory. Each thread contributes an array of input elements.

\granularity
\smemreuse

Snippet: The code snippet below illustrates a 256-bin histogram of 512 integer samples that are partitioned across 128 threads where each thread owns 4 samples.

: #include <cub/cub.cuh> // or equivalently <cub/block/block_histogram.cuh>
__global__ void ExampleKernel(...)
{
// Specialize a 256-bin BlockHistogram type for a 1D block of 128 threads having 4 character samples each
typedef cub::BlockHistogram<unsigned char, 128, 4, 256> BlockHistogram;
// Allocate shared memory for BlockHistogram
__shared__ typename BlockHistogram::TempStorage temp_storage;
// Allocate shared memory for block-wide histogram bin counts
__shared__ unsigned int smem_histogram[256];
// Obtain input samples per thread
unsigned char thread_samples[4];
...
// Compute the block-wide histogram
BlockHistogram(temp_storage).Histogram(thread_samples, smem_histogram);

Template Parameters

CounterT [inferred] Histogram counter type

Parameters

[in]	items	Calling thread's input values to histogram
[out]	histogram	Reference to shared/device-accessible memory histogram

Definition at line 347 of file block_histogram.cuh.

◆ InitHistogram()

template<typename T , int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>

template<typename CounterT >

__device__ __forceinline__ void cub::BlockHistogram< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, ALGORITHM, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >::InitHistogram ( CounterT histogram[BINS] )

inline

Initialize the shared histogram counters to zero.

Snippet: The code snippet below illustrates a the initialization and update of a histogram of 512 integer samples that are partitioned across 128 threads where each thread owns 4 samples.

: #include <cub/cub.cuh> // or equivalently <cub/block/block_histogram.cuh>
__global__ void ExampleKernel(...)
{
// Specialize a 256-bin BlockHistogram type for a 1D block of 128 threads having 4 character samples each
typedef cub::BlockHistogram<unsigned char, 128, 4, 256> BlockHistogram;
// Allocate shared memory for BlockHistogram
__shared__ typename BlockHistogram::TempStorage temp_storage;
// Allocate shared memory for block-wide histogram bin counts
__shared__ unsigned int smem_histogram[256];
// Obtain input samples per thread
unsigned char thread_samples[4];
...
// Initialize the block-wide histogram
BlockHistogram(temp_storage).InitHistogram(smem_histogram);
// Update the block-wide histogram
BlockHistogram(temp_storage).Composite(thread_samples, smem_histogram);

Template Parameters

CounterT [inferred] Histogram counter type

Definition at line 291 of file block_histogram.cuh.

Field Documentation

◆ SAFE_ALGORITHM

template<typename T , int BLOCK_DIM_X, int ITEMS_PER_THREAD, int BINS, BlockHistogramAlgorithm ALGORITHM = BLOCK_HISTO_SORT, int BLOCK_DIM_Y = 1, int BLOCK_DIM_Z = 1, int PTX_ARCH = CUB_PTX_ARCH>

const BlockHistogramAlgorithm cub::BlockHistogram< T, BLOCK_DIM_X, ITEMS_PER_THREAD, BINS, ALGORITHM, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH >::SAFE_ALGORITHM

staticprivate

Initial value:

=
        ((ALGORITHM == BLOCK_HISTO_ATOMIC) && (PTX_ARCH < 120)) ?
            BLOCK_HISTO_SORT :
            ALGORITHM

Ensure the template parameterization meets the requirements of the targeted device architecture. BLOCK_HISTO_ATOMIC can only be used on version SM120 or later. Otherwise BLOCK_HISTO_SORT is used regardless.

Definition at line 178 of file block_histogram.cuh.

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

openfpm_data/src/util/cuda/cub_old/block/block_histogram.cuh

Detailed Description

Data Structures

Public Member Functions

Private Types

Private Member Functions

Private Attributes

Static Private Attributes

Member Enumeration Documentation

◆ anonymous enum

Constructor & Destructor Documentation

◆ BlockHistogram()

Member Function Documentation

◆ Composite()

◆ Histogram()

◆ InitHistogram()

Field Documentation

◆ SAFE_ALGORITHM