>> You may specify:
>> --mca btl openib,sm,self
> Application sometime runs fast, sometimes runs slow
When you specify the parameter above, open mpi will use only three btls
openib - for Infiniband
sm - for shared memory communication
self - for "self" communication
NO other btl will be used.
>> And OpenMPI will use IB and shared memory for communication.
>> --mca btl tcp,sm,self
> Allpication always runs fast. So...
> is there a way to determine (from my application code) which
> BTL is really being used?
And with this parameter you use TCP btl instead of IB.
So you see better performance with tcp btl ?!
I'm not sure that you may see list of active btls in 1.2.X. But anyway
when you explicitly specify BTLs in command line, only these btls are used.
> I appreciate any help I can get,
>> And OpenMPI will use TCP and shared memory for communication.
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