event CCL_API alltoall (const void *send_buf, void *recv_buf, size_t count, datatype dtype, const communicator &comm, const stream &stream, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

Alltoall is a collective communication operation in which each rank sends distinct equal-sized blocks of data to each rank. The j-th block of send_buf sent from the i-th rank is received by the j-th rank and is placed in the i-th block of recvbuf.

Parameters

• send_buf – the buffer with count elements of dtype that stores local data to be sent

• recv_buf – [out] the buffer to store received result, must be large enough to hold values from all ranks, i.e. at least comm_size * count

• count – the number of elements of type dtype to be send to or to received from each rank

• dtype – the datatype of elements in send_buf and recv_buf

• comm – the communicator for which the operation will be performed

• stream – abstraction over a device queue constructed via ccl::create_stream

• attr – optional attributes to customize operation

• deps – an optional vector of the events that the operation should depend on

Returns

ccl::event an object to track the progress of the operation

event CCL_API alltoall (const void *send_buf, void *recv_buf, size_t count, datatype dtype, const communicator &comm, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

event CCL_API alltoall (const vector_class< void * > &send_buf, const vector_class< void * > &recv_buf, size_t count, datatype dtype, const communicator &comm, const stream &stream, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank

event CCL_API alltoall (const vector_class< void * > &send_buf, const vector_class< void * > &recv_buf, size_t count, datatype dtype, const communicator &comm, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank

template<class BufferType, class = typename std::enable_if<is_native_type_supported<BufferType>(), event>::type> event CCL_API alltoall (const BufferType *send_buf, BufferType *recv_buf, size_t count, const communicator &comm, const stream &stream, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

template<class BufferType, class = typename std::enable_if<is_native_type_supported<BufferType>(), event>::type> event CCL_API alltoall (const BufferType *send_buf, BufferType *recv_buf, size_t count, const communicator &comm, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

template<class BufferType, class = typename std::enable_if<is_native_type_supported<BufferType>(), event>::type> event CCL_API alltoall (const vector_class< BufferType * > &send_buf, const vector_class< BufferType * > &recv_buf, size_t count, const communicator &comm, const stream &stream, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank

template<class BufferType, class = typename std::enable_if<is_native_type_supported<BufferType>(), event>::type> event CCL_API alltoall (const vector_class< BufferType * > &send_buf, const vector_class< BufferType * > &recv_buf, size_t count, const communicator &comm, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank

template<class BufferObjectType, class = typename std::enable_if<is_class_supported<BufferObjectType>(), event>::type> event CCL_API alltoall (const BufferObjectType &send_buf, BufferObjectType &recv_buf, size_t count, const communicator &comm, const stream &stream, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

template<class BufferObjectType, class = typename std::enable_if<is_class_supported<BufferObjectType>(), event>::type> event CCL_API alltoall (const BufferObjectType &send_buf, BufferObjectType &recv_buf, size_t count, const communicator &comm, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank

template<class BufferObjectType, class = typename std::enable_if<is_class_supported<BufferObjectType>(), event>::type> event CCL_API alltoall (const vector_class< reference_wrapper_class< BufferObjectType >> &send_buf, const vector_class< reference_wrapper_class< BufferObjectType >> &recv_buf, size_t count, const communicator &comm, const stream &stream, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank

template<class BufferObjectType, class = typename std::enable_if<is_class_supported<BufferObjectType>(), event>::type> event CCL_API alltoall (const vector_class< reference_wrapper_class< BufferObjectType >> &send_buf, const vector_class< reference_wrapper_class< BufferObjectType >> &recv_buf, size_t count, const communicator &comm, const alltoall_attr &attr=default_alltoall_attr, const vector_class< event > &deps={})

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Type-safe version.

Parameters

• send_bufs – array of buffers with local data to be sent, one buffer per rank

• recv_bufs – [out] array of buffers to store received result, one buffer per rank