2.5.6-1 (#255)

Add LL128 Protocol.

Rewrite the topology detection and tree/ring creation (#179). Improve
tree performance by sending/receiving from different GPUs. Add
model-based tuning to switch between the different algorithms and
protocols.

Rework P2P/SHM detection in containers (#155, #248).

Detect duplicated devices and return an error (#231).

Add tuning for GCP

src/include/bootstrap.h

@@ -17,4 +17,5 @@ ncclResult_t bootstrapAllGather(void* commState, void* allData, int size);
 ncclResult_t bootstrapSend(void* commState, int peer, void* data, int size);
 ncclResult_t bootstrapRecv(void* commState, int peer, void* data, int size);
 ncclResult_t bootstrapClose(void* commState);
+ncclResult_t bootstrapAbort(void* commState);
 #endif