ggml-org/llama.cpp b12079

on GitHub

Add nccl support for multi-node tensor parallelism (#28967)

• Add a backend interface for collectives across ranks running in separate processes, implement it in the CUDA backend using NCCL, and use it in the RPC server when available.

• Drop ggml_backend_comm_allreduce_rank_t and reuse ggml_backend_comm_allreduce_tensor for per-rank communicators

• reuse ggml_backend_cuda_comm_allreduce_nccl for per-rank communicators. Remove the helper function backend_comm_proc_address

• Change ggml_backend_comm_get_unique_id_t and ggml_backend_comm_init_rank_t to more generic multi-process backend communicator interfaces

• set maxCTAs in ncclConfig_t to 8 for dgx spark in ggml_backend_cuda_comm_init_rank