[Beowulf] NAMD/CUDA scaling: QDR Infiniband sufficient?
Nifty Tom Mitchell
niftyompi at niftyegg.com
Mon Feb 9 15:51:28 PST 2009
On Mon, Feb 09, 2009 at 03:37:06PM -0500, Dow Hurst DPHURST wrote:
> Subject: [Beowulf] NAMD/CUDA scaling: QDR Infiniband sufficient?
> Has anyone tested scaling of NAMD/CUDA over QLogic or ConnectX QDR
> interconnects for a large number of IB cards and GPUs? I've listened
> to John Stone's presentation on VMD and NAMD CUDA acceleration. The
> consensus I brought away from the presentation was that one QDR per GPU
> would probably be necessary to scale efficiently. The 60 node, 60 GPU,
> DDR IB enabled cluster that was used for initial testing was saturating
> the interconnect. Later tests on the new GT200 based cards show even
> more performance gains for the GPUs. 1 GPU performing the work of 12
> CPUs or 8 CPUs equaling 96 cores were the numbers I saw. So with a
> ratio of 1gpu/12cores, interconnect performance will be very important.
Because of the GPU aspect I doubt any vendor has tested this. The chassis
is a consideration needing multiple PCI Express 2.0 x16 slots for the
GPU cards and an additional PCIe x16 slot for the IB card with memory
system bandwidth to match.
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