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Subject: Re: [OMPI users] RDMA GPUDirect CUDA...
From: Rolf vandeVaart (rvandevaart_at_[hidden])
Date: 2012-08-14 17:39:28


To answer the original questions, Open MPI will look at taking advantage of the RDMA CUDA when it is available. Obviously, work needs to be done to figure out the best way to integrate into the library. Much like there are a variety of protocols under the hood to support host transfer of data via IB, we will have to see what works best for transferring GPU buffers.

It is unclear how this will affect the send/receive latency.

Lastly, the support will be for Kepler -class Quadro and Tesla devices.

Rolf

From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On Behalf Of Durga Choudhury
Sent: Tuesday, August 14, 2012 4:46 PM
To: Open MPI Users
Subject: Re: [OMPI users] RDMA GPUDirect CUDA...

Dear OpenMPI developers

I'd like to add my 2 cents that this would be a very desirable feature enhancement for me as well (and perhaps others).

Best regards
Durga

On Tue, Aug 14, 2012 at 4:29 PM, Zbigniew Koza <zzkoza_at_[hidden]<mailto:zzkoza_at_[hidden]>> wrote:
Hi,

I've just found this information on nVidia's plans regarding enhanced support for MPI in their CUDA toolkit:
http://developer.nvidia.com/cuda/nvidia-gpudirect

The idea that two GPUs can talk to each other via network cards without CPU as a middleman looks very promising.
This technology is supposed to be revealed and released in September.

My questions:

1. Will OpenMPI include RDMA support in its CUDA interface?
2. Any idea how much can this technology reduce the CUDA Send/Recv latency?
3. Any idea whether this technology will be available for Fermi-class Tesla devices or only for Keplers?

Regards,

Z Koza

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