[Beowulf] building Infiniband 4x cluster questions

[Gilad Shainer]

There is some add latency due to the 66/64 new encoding, but overall latency is lower than QDR. MPI is below 1us.

Gilad


-----Original Message-----
From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of Christopher Samuel
Sent: Sunday, November 13, 2011 6:42 PM
To: beowulf at beowulf.org
Subject: Re: [Beowulf] building Infiniband 4x cluster questions

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Hi Gilad,

On 08/11/11 12:53, Gilad Shainer wrote:

> The latency numbers are more or less the same between the IB vendors 
> on SDR, DDR and QDR. Mellanox is the only vendor with FDR IB for now, 
> and with PCIe 3.0 latency are below 1us (RDMA much below...).

Is that for an MPI message ?  I'd heard that FDR might have higher latencies due to the coding changes that were happening - is this not the case ?

cheers,
Chris
- -- 
    Christopher Samuel - Senior Systems Administrator  VLSCI - Victorian Life Sciences Computation Initiative
 Email: samuel at unimelb.edu.au Phone: +61 (0)3 903 55545
         http://www.vlsci.unimelb.edu.au/

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