Hi,
We recently noticed openmpi is using btl openib over self,sm for single node jobs, which has caused performance degradation for some applications, e.g. 'cp2k'. For opempi version 2.0.1, our test shows single node 'cp2k' job using openib is ~25% slower than using self,sm. We advise users do '--mca btl_base_exclude openib' as a temporary fix. I need to point out that not all applications are affected by this feature. Many of them have the same single-node performance with/without openib. Why doesn't openmpi use self,sm by default for single node jobs? Is this the intended behavior? Thanks, Jingchao
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