Allreduce

event allreduce(const void *send_buf, void *recv_buf, size_t count, datatype dtype, reduction rtype, const communicator &comm, const stream &stream, const allreduce_attr &attr = default_allreduce_attr, const vector_class<event> &deps = {})

Allreduce is a collective communication operation that performs the global reduction operation on values from all ranks of communicator and distributes the result back to all ranks.

Return

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

Parameters

  • send_buf: the buffer with count elements of dtype that stores local data to be reduced

  • recv_buf: [out] the buffer to store reduced result, must have the same dimension as send_buf

  • count: the number of elements of type dtype in send_buf and recv_buf

  • dtype: the datatype of elements in send_buf and recv_buf

  • rtype: the type of the reduction operation to be applied

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

  • stream: a stream associated with the operation

  • attr: optional attributes to customize operation

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

event allreduce(const void *send_buf, void *recv_buf, size_t count, datatype dtype, reduction rtype, const communicator &comm, const allreduce_attr &attr = default_allreduce_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.

template<class BufferType, class = typename std::enable_if<is_native_type_supported<BufferType>(), event>::type>
event allreduce(const BufferType *send_buf, BufferType *recv_buf, size_t count, reduction rtype, const communicator &comm, const stream &stream, const allreduce_attr &attr = default_allreduce_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.

template<class BufferType, class = typename std::enable_if<is_native_type_supported<BufferType>(), event>::type>
event allreduce(const BufferType *send_buf, BufferType *recv_buf, size_t count, reduction rtype, const communicator &comm, const allreduce_attr &attr = default_allreduce_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.

template<class BufferObjectType, class = typename std::enable_if<is_class_supported<BufferObjectType>(), event>::type>
event allreduce(const BufferObjectType &send_buf, BufferObjectType &recv_buf, size_t count, reduction rtype, const communicator &comm, const stream &stream, const allreduce_attr &attr = default_allreduce_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.

template<class BufferObjectType, class = typename std::enable_if<is_class_supported<BufferObjectType>(), event>::type>
event allreduce(const BufferObjectType &send_buf, BufferObjectType &recv_buf, size_t count, reduction rtype, const communicator &comm, const allreduce_attr &attr = default_allreduce_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.

Allgatherv Alltoall