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Subject: Re: [OMPI devel] RDMA with non-contiguous payload
From: Rolf vandeVaart (rvandevaart_at_[hidden])
Date: 2012-01-04 10:37:50


Your observations are correct. If the payload is non-contiguous, then RDMA is not used. The data has to be copied first into an intermediate buffer and then sent.
This has not changed in later version of Open MPI.

Rolf

>-----Original Message-----
>From: devel-bounces_at_[hidden] [mailto:devel-bounces_at_[hidden]]
>On Behalf Of Sebastian Rinke
>Sent: Wednesday, January 04, 2012 10:01 AM
>To: Open MPI Developers
>Subject: [OMPI devel] RDMA with non-contiguous payload
>
>Dear all,
>
>Playing around with GPUDirect v1 and Infiniband I noticed that once the
>payload is non-contiguous no RDMA is used at all.
>Can anybody confirm this?
>
>I'm using Open MPI 1.4.3. If the above is true, has this behavior changed with
>later versions of Open MPI?
>
>Thanks a lot.
>
>Best,
>Sebastian
>_______________________________________________
>devel mailing list
>devel_at_[hidden]
>http://www.open-mpi.org/mailman/listinfo.cgi/devel
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