graph: restrict maxChannels to 64 for multi-node and RCCL_ENABLE_INTRANET=1

src/graph/connect.cc

@@ -627,6 +627,10 @@ ncclResult_t ncclTopoPostset(struct ncclComm* comm, int* firstRanks, int* treePa
   // Only use full MAXCHANNELS for gfx94x
   int maxChannels = IsArchMatch(comm->topo->nodes[GPU].nodes[0].gpu.gcn, "gfx94") ? MAXCHANNELS : 2*CHANNEL_LIMIT;
 
+  if (graphs[NCCL_ALGO_RING]->nIntraChannels > 0 || comm->nNodes > 1) {
+        maxChannels = std::min(64, maxChannels);
+  }
+
   // Duplicate ringPrev/ringNext for ncclBuildRing
   if (nChannels <= maxChannels/2) memcpy(ringPrev+nChannels*nranks, ringPrev, nChannels*nranks*sizeof(int));
   if (nChannels <= maxChannels/2) memcpy(ringNext+nChannels*nranks, ringNext, nChannels*nranks*sizeof(int));