Overview

group

Process groups that participate in collective communication. The process groups include:

• hccl_world_group: default global group, including all ranks that participate in collective communication. This group is created using the rank table file.
• Custom group: a subset of the process groups contained in the hccl_world_group. The ranks in the rank table file can be defined as different groups through the create_group API, and the collective communication algorithms can be executed in parallel.

rank

A communication entity in the group. Each rank is assigned a unique ID ranging from 0 to n – 1 (n is the number of NPUs).

rank size

• Rank size: indicates the number of ranks in a group.
• Local rank size: indicates the number of ranks in a group on the server where the processes are located.

rank id

• Rank ID: indicates the ID of a process in a group. The value ranges from 0 to (rank size – 1). For a user-defined group, the rank starts from 0 in the group. For hccl_world_group, the rank ID is the same as the world rank ID.
• World rank ID: indicates the rank ID of a process in hccl_world_group. The value ranges from 0 to (rank size – 1).
• Local rank ID: indicates the rank ID of a process in a group on the server where the process is located. The value ranges from 0 to (local rank size – 1).