diff --git a/projects/rccl/src/graph/connect.cc b/projects/rccl/src/graph/connect.cc index 55b3a6491e..f00a34fd8c 100644 --- a/projects/rccl/src/graph/connect.cc +++ b/projects/rccl/src/graph/connect.cc @@ -668,7 +668,12 @@ ncclResult_t ncclTopoPostset(struct ncclComm* comm, int* firstRanks, int* treePa nChannels = comm->nChannels = copyChannels(comm, nChannels, 2*nChannels, ringPrev, ringNext); } - int minNchannels = ncclMinNchannels(); + int minNchannels = 64; + if (comm->nNodes == 1) { + minNchannels = ncclMinNchannels(); + } else { + minNchannels = std::min(64,ncclMinNchannels()); + } if (mscclEnabled() && (comm->topo->mscclEnabled || mscclForceEnabled())) { int mscclNumChannelsRequired = 0;