2.8.3-1

Optimization for Tree allreduce on A100.
Improve aggregation performance.
Use shared buffers for inter-node send/recv.
Add NVTX profiling hooks.
Accelerate alltoall connections by merging communication for all
channels.
Add support for one hop communication through NVLink, for faster
send/recv communication on cubemesh topologies like DGX-1.
Improve alltoall scheduling to better balance intra/inter node
communication.
Increase send/recv parallelism by 8x, each warp sending or
receiving to a different peer.
Net: move to v4.
Net: make flush operation asynchronous to accelerate alltoall.
Net: define maximum number of requests.
Fix hang when using LL128 protocol after 2^31 steps.
Fix #379 : topology injection failing when using less GPUs than
described in the XML.
Fix #394 : protocol mismatch causing hangs or crashes when using
one GPU per node.

src/graph/rings.cc

@@ -21,7 +21,7 @@ void dumpLine(int* values, int nranks, const char* prefix) {
 
 ncclResult_t ncclBuildRings(int nrings, int* rings, int rank, int nranks, int* prev, int* next) {
   for (int r=0; r<nrings; r++) {
-    char prefix[30];
+    char prefix[40];
     /*sprintf(prefix, "[%d] Channel %d Prev : ", rank, r);
     dumpLine(prev+r*nranks, nranks, prefix);
     sprintf(prefix, "[%d] Channel %d Next : ", rank, r);