HcclAllGather

Description

Re-sorts the inputs of all ranks in the communicator by rank ID, combines the inputs, and sends the results to the outputs of all ranks.

For the AllGather operation, each rank receives a set of data that is resorted based on a rank ID, that is, AllGather outputs of all ranks are the same.

Prototype

HcclResult HcclAllGather(void *sendBuf, void *recvBuf, uint64_t sendCount, HcclDataType dataType, 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.
sendCount	Input	sendBuf size involved in AllGather operation. The size of recvBuf data is calculated as: count x rank size.
dataType	Input	Data type of the Allgather operation, which is of the HcclDataType type. Atlas Training Series Product: The supported data types are int8, uint8, int16, uint16, int32, uint32, int64, uint64, float16, float32, and float64.
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 sendCount and dataType.

Applicability

Atlas Training Series Product

Parent topic: Collective Communication