eric-haibin-lin commented on a change in pull request #17235: [DOC] Add a few 
tips for running horovod
URL: https://github.com/apache/incubator-mxnet/pull/17235#discussion_r363945955
 
 

 ##########
 File path: example/distributed_training-horovod/README.md
 ##########
 @@ -199,3 +199,11 @@ $ mpirun -np 8 \
     -mca pml ob1 -mca btl ^openib \
     python train.py
 ```
+
+## Tuning Horovod Performance
+
+1. To analyse horovod performance, [horovod 
timeline](https://github.com/horovod/horovod/blob/master/docs/timeline.rst) is 
a handy tool to trace and visualize the time spent on horovod operations. 
+
+2. A few tuning knobs affect horovod runtime performance (explained 
[here](https://github.com/horovod/horovod/blob/master/docs/tensor-fusion.rst)). 
Apart from `HOROVOD_FUSION_THRESHOLD`, sometimes we find increasing 
`HOROVOD_CYCLE_TIME` (up to 100 ms), changing 
[`NCCL_ALGO`](https://docs.nvidia.com/deeplearning/sdk/nccl-developer-guide/docs/env.html#nccl-algo),
 and `NCCL_MIN_NCHANNELS` improves performance.
 
 Review comment:
   I'll do that

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