HcclAllReduce

Description

Adds the input data of all nodes in the communicator (or performs other reduction operations) and sends the result to the output buffer of all nodes. The reduction operation type is specified by the op parameter.

Prototype

HcclResult HcclAllReduce(void *sendBuf, void *recvBuf, uint64_t count, HcclDataType dataType, HcclReduceOp op, HcclComm comm, aclrtStream stream)

Parameters

Parameter	Input/Output	Description
sendBuf	Input	Address of the buffer to send source data.
recvBuf	Output	Address of the buffer to receive collective communication result.
count	Input	Number of data elements to perform AllReduce operation. For example, if only one int32 data element is involved, then count = 1.
dataType	Input	Data type of the AllReduce operation, which is of the HcclDataType type. Atlas Training Series Product : The supported data types are int8, int32, int64, float16, and float32.
op	Input	Reduction operation type. Currently, the following operation types are supported: sum, prod, max, and min. NOTE:
comm	Input	Communicator where the operation is performed.
stream	Input	Stream of the rank.

Returns

HcclResult: HCCL_SUCCESS on success; else, failure.

Constraints

The ranks must have the same count, dataType, and op.
Each rank has only one input.

Applicability

Atlas Training Series Product

Example

For details, see the HcclAllReduce operation code example of each communicator initialization mode in Example Code.

Parent topic: Collective Communication