[mpich-discuss] mpich collectives topology aware?

[Darius Buntinas]

Yes, I believe all collectives are topology aware.  I checked Allreduce specifically, and it does what you describe.

-d


On Nov 24, 2010, at 1:29 PM, Filip Blagojevic wrote:

> Hi,
> 
> Could anyone tell me if MPI_Allreduce() (and other collectives) is topology aware?
> More specifically, I would like to know if MPI_Allreduce() will first perform a local reduction (within a single shared memory node), and then only one MPI rank will be chosen on each node to perform inter-node reduction. Or maybe the reduction is not aware of what MPI processes are sharing a node?
> 
> Thank you,
> Filip_______________________________________________
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