SkePU 0.7
Public Member Functions | Static Public Member Functions
skepu::Reduce< ReduceFunc, T > Class Template Reference

A class representing the Reduce skeleton. More...

#include <reduce.h>

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List of all members.

Public Member Functions

 Reduce (ReduceFunc *reduceFunc)
 Reduce (ReduceFunc *reduceFunc, Vector< T > *in, T *out)
 ~Reduce ()
void run_async ()
operator() (Vector< T > &input)
operator() (Vector< T > &input, int parts)
void replaceText (std::string &text, std::string find, std::string replace)
void createOpenCLProgram ()

Static Public Member Functions

static void cpu_func (void *buffers[], void *arg)
static void omp_func (void *buffers[], void *arg)
static void cuda_func (void *buffers[], void *arg)
static void opencl_func (void *buffers[], void *arg)

Detailed Description

template<typename ReduceFunc, typename T>
class skepu::Reduce< ReduceFunc, T >

A class representing the Reduce skeleton.

Author:
Johan Enmyren, Usman Dastgeer
Version:
0.7

This class defines the Reduce skeleton which applies a commutative associative binary operator between each element in the input range, yielding a scalar result. Once instantiated, it is meant to be used as a function and therefore overloading operator(). The Reduce skeleton needs to be created with a binary user function.

It uses StarPU as a backend and choice between different backends can be controlled by using defines. SKEPU_OPENMP can be used to use OpenMP whose support is currently limited in StarPU, hence not recommended, SKEPU_CUDA will register CUDA backend along other defined (atleast CPU if nothing else is defined) SKEPU_OPENCL will register OpenCL backend along other defined (atleast CPU if nothing else is defined) CUDA_ONLY will eliminate all other backends (even CPU) and will force StarPU to use CUDA only. if no above macro is defined, it will use sequential CPU backend.


Constructor & Destructor Documentation

template<typename ReduceFunc , typename T >
skepu::Reduce< ReduceFunc, T >::Reduce ( ReduceFunc *  reduceFunc)

When creating an instance of the Reduce skeleton, a pointer to a binary user function must be provided. Also the environment is set and if SKEPU_OPENCL is defined, the appropriate OpenCL program is created.

Parameters:
reduceFuncA pointer to a valid binary user function. Will be deleted in the destructor.

References skepu::Environment< T >::getInstance().

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template<typename ReduceFunc , typename T >
skepu::Reduce< ReduceFunc, T >::Reduce ( ReduceFunc *  reduceFunc,
Vector< T > *  in,
T *  out 
)

When creating an instance of the Reduce skeleton, a pointer to a binary user function must be provided. Also the environment is set and if SKEPU_OPENCL is defined, the appropriate OpenCL program is created. This constructor is used to assist in calling map skeleton in a task-parallel skeleton(e.g. farm) by implementing Task class "run_async()" method. The parameters for map call should be specified before e.g. using this constructor.

Parameters:
reduceFuncA pointer to a valid binary user function. Will be deleted in the destructor.
inA pointer to a input Vector object.
outA pointer to an output variable.

References skepu::Environment< T >::getInstance().

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template<typename ReduceFunc , typename T >
skepu::Reduce< ReduceFunc, T >::~Reduce ( )

When the Reduce skeleton is destroyed, it deletes the user function it was created with. Furthermore, it destroy OpenCL handler and performance model objects (if created) and StarPU codelet.


Member Function Documentation

template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::cpu_func ( void *  buffers[],
void *  arg 
) [static]

A static function used with StarPU codelet for applying Reduce and is called by the StarPU if CPU backend is selected for a skeleton invocation.

Parameters:
buffersContain all StarPU managed data which in this case consists of one read and one write buffer.
argA read only argument which is used to pass handler to the object as this is a static function.
template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::createOpenCLProgram ( )

A function called by the constructor. It creates the OpenCL program for the skeleton and saves the kernel name. The program is built from a string containing the user function (specified when constructing the skeleton) and a generic Reduce kernel. The type and function names in the generic kernel are relpaced by user function specific code before it is compiled by the OpenCL JIT compiler.

Also handles the use of doubles automatically by including "#pragma OPENCL EXTENSION cl_khr_fp64: enable" if doubles are used.

References skepu::ReduceKernel_CL().

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template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::cuda_func ( void *  buffers[],
void *  arg 
) [static]

A static function used with StarPU codelet for applying Reduce and is called by the StarPU if CUDA backend is selected for a skeleton invocation.

Parameters:
buffersContain all StarPU managed data which in this case consists of one read and one write buffer.
argA read only argument which is used to pass handler to the object as this is a static function.
template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::omp_func ( void *  buffers[],
void *  arg 
) [static]

A static function used with StarPU codelet for applying Reduce and is called by the StarPU if OpenMP backend is selected for a skeleton invocation.

Parameters:
buffersContain all StarPU managed data which in this case consists of one read and one write buffer.
argA read only argument which is used to pass handler to the object as this is a static function.
template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::opencl_func ( void *  buffers[],
void *  arg 
) [static]

A static function used with StarPU codelet for applying Reduce and is called by the StarPU if OpenCL backend is selected for a skeleton invocation.

Parameters:
buffersContain all StarPU managed data which in this case consists of one read and one write buffer.
argA read only argument which is used to pass handler to the object as this is a static function.
template<typename ReduceFunc , typename T >
T skepu::Reduce< ReduceFunc, T >::operator() ( Vector< T > &  input)

Performs the Reduction on a whole Vector. Returns a scalar result.

Depending on which backend was used, appropriate backend will be registered. In case of multiple backends (e.g. CPU and CUDA) StarPU will decide at runtime which one to use.

Parameters:
inputA vector which the reduction will be performed on.
Returns:
The scalar result of the reduction performed.
template<typename ReduceFunc , typename T >
T skepu::Reduce< ReduceFunc, T >::operator() ( Vector< T > &  input,
int  parts 
)

Performs the Reduction on a whole Vector. It has support for creating multiple tasks using filters/partitioning. Returns a scalar result.

Depending on which backend was used, appropriate backend will be registered. In case of multiple backends (e.g. CPU and CUDA) StarPU will decide at runtime which one to use.

Parameters:
inputA vector which the reduction will be performed on.
partsThe number of parts (StarPU tasks) that will be created for this skeleton call dividing the work equally between different created tasks.
Returns:
The scalar result of the reduction performed.

References skepu::Vector< T >::registerPartitions(), skepu::Vector< T >::resize(), and skepu::Vector< T >::size().

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template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::replaceText ( std::string &  text,
std::string  find,
std::string  replace 
)

A helper function used by createOpenCLProgram(). It finds all instances of a string in another string and replaces it with a third string.

Parameters:
textA std::string which is searched.
findThe std::string which is searched for and replaced.
replaceThe relpacement std::string.
template<typename ReduceFunc , typename T >
void skepu::Reduce< ReduceFunc, T >::run_async ( ) [virtual]

This is an abstract method defined in the Task class which every data-parallel skeleton implements to allow itself to be used within task-parallel skeletons (e.g. farm). It relies on the fact that parameters for the function call are already provided e.g. via constructor or setter methods available in the public interface of the class.

Implements skepu::Task.


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