Some puzzled problems about algorithm

[Luckyton]

Hello,

I have been reading ucc source code of version 1.3.0 and found some puzzled problems releated to algorithm.

Firstly, there is no default ucc_msg_range_t for scatter at score map of tl_ucp component. When creating scatter task with UCC_CLS=basic and UCC_CL_BASIC_TLS=ucp, which init function will be called ?

Secondly, when length of message is bigger than 4k, there is no ucc_msg_range_t for allreduce and bcast at score map of cl_hier component. When creating task with UCC_CLS=hier and UCC_CL_HIER_TLS=ucp, which init function will be called ?

Lastly, the processing procedure of knomial scatter algorithm at tl_ucp component is shown in the following figure. I doesn't seem to have achieved scatter option. Because it doesn't send ith segment to rank i. Am I right ?

thank you!

[Sergei-Lebedev]

Hi @Luckyton, if still rellevant.

Firstly, there is no default ucc_msg_range_t for scatter at score map of tl_ucp component. When creating scatter task with UCC_CLS=basic and UCC_CL_BASIC_TLS=ucp, which init function will be called ?

TL UCP doesn't have scatter implementation, scatter collective in TL UCP is used only as part of bcast sag algorithm.

Secondly, when length of message is bigger than 4k, there is no ucc_msg_range_t for allreduce and bcast at score map of cl_hier component. When creating task with UCC_CLS=hier and UCC_CL_HIER_TLS=ucp, which init function will be called ?

This is just default configuration, you can adjust it if needed. In this case CL BASIC TL UCP will be used. You can see all the ranges with UCC_LOG_LEVEL=info (https://github.com/openucx/ucc/blob/master/docs/user_guide.md)

Lastly, the processing procedure of knomial scatter algorithm at tl_ucp component is shown in the following figure. I doesn't seem to have achieved scatter option. Because it doesn't send ith segment to rank i. Am I right ?

Right, scatter_knomial is not an implementation of scatter collective.