LightGBM::Network Class Reference

A static class that contains some collective communication algorithm. More...

#include <network.h>

Static Public Member Functions
static void	Init (Config config)
	Initialize.
static void	Init (int num_machines, int rank, ReduceScatterFunction reduce_scatter_ext_fun, AllgatherFunction allgather_ext_fun)
	Initialize.
static void	Dispose ()
	Free this static class.
static int	rank ()
	Get rank of this machine.
static int	num_machines ()
	Get total number of machines.
static void	Allreduce (char *input, comm_size_t input_size, int type_size, char *output, const ReduceFunction &reducer)
	Perform all_reduce. if data size is small, will perform AllreduceByAllGather, else with call ReduceScatter followed allgather.
static void	AllreduceByAllGather (char *input, comm_size_t input_size, int type_size, char *output, const ReduceFunction &reducer)
	Perform all_reduce by using all_gather. it can be use to reduce communication time when data is small.
static void	Allgather (char *input, comm_size_t send_size, char *output)
	Performing all_gather by using bruck algorithm. Communication times is O(log(n)), and communication cost is O(send_size * number_machine) It can be used when all nodes have same input size.
static void	Allgather (char *input, const comm_size_t *block_start, const comm_size_t *block_len, char *output, comm_size_t all_size)
	Performing all_gather by using bruck algorithm. Communication times is O(log(n)), and communication cost is O(all_size) It can be used when nodes have different input size.
static void	ReduceScatter (char *input, comm_size_t input_size, int type_size, const comm_size_t *block_start, const comm_size_t *block_len, char *output, comm_size_t output_size, const ReduceFunction &reducer)
	Perform reduce scatter by using recursive halving algorithm. Communication times is O(log(n)), and communication cost is O(input_size)
template<class T >
static T	GlobalSyncUpByMin (T &local)
template<class T >
static T	GlobalSyncUpByMax (T &local)
template<class T >
static T	GlobalSyncUpByMean (T &local)
template<class T >
static void	GlobalSum (std::vector< T > &local)

Detailed Description

A static class that contains some collective communication algorithm.

Member Function Documentation

Allgather() [1/2]

void LightGBM::Network::Allgather ( char *  input, comm_size_t  send_size, char *  output  )

static

Performing all_gather by using bruck algorithm. Communication times is O(log(n)), and communication cost is O(send_size * number_machine) It can be used when all nodes have same input size.

Parameters

input	Input data
send_size	The size of input data
output	Output result

Allgather() [2/2]

void LightGBM::Network::Allgather ( char *  input, const comm_size_t *  block_start, const comm_size_t *  block_len, char *  output, comm_size_t  all_size  )

static

Performing all_gather by using bruck algorithm. Communication times is O(log(n)), and communication cost is O(all_size) It can be used when nodes have different input size.

Parameters

input	Input data
block_start	The block start for different machines
block_len	The block size for different machines
output	Output result
all_size	The size of output data

Allreduce()

void LightGBM::Network::Allreduce ( char *  input, comm_size_t  input_size, int  type_size, char *  output, const ReduceFunction &  reducer  )

static

Perform all_reduce. if data size is small, will perform AllreduceByAllGather, else with call ReduceScatter followed allgather.

Parameters

input	Input data
input_size	The size of input data
type_size	The size of one object in the reduce function
output	Output result
reducer	Reduce function

AllreduceByAllGather()

void LightGBM::Network::AllreduceByAllGather ( char *  input, comm_size_t  input_size, int  type_size, char *  output, const ReduceFunction &  reducer  )

static

Perform all_reduce by using all_gather. it can be use to reduce communication time when data is small.

Parameters

input	Input data
input_size	The size of input data
type_size	The size of one object in the reduce function
output	Output result
reducer	Reduce function

Init()

void LightGBM::Network::Init ( Config  config )

static

Initialize.

Parameters

config

Config of network setting

ReduceScatter()

void LightGBM::Network::ReduceScatter ( char *  input, comm_size_t  input_size, int  type_size, const comm_size_t *  block_start, const comm_size_t *  block_len, char *  output, comm_size_t  output_size, const ReduceFunction &  reducer  )

static

Perform reduce scatter by using recursive halving algorithm. Communication times is O(log(n)), and communication cost is O(input_size)

Parameters

input	Input data
input_size	The size of input data
type_size	The size of one object in the reduce function
block_start	The block start for different machines
block_len	The block size for different machines
output	Output result
output_size	size of output data
reducer	Reduce function

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

• External/LightGBM_2.2.3/LightGBM-2.2.3/include/LightGBM/network.h
• External/LightGBM_2.2.3/LightGBM-2.2.3/src/network/network.cpp