[Beowulf] Cheap SDR IB

[richard.walsh at comcast.net]

Gilad Shainer wrote:
 
> With more cores on a single node, the IB benefits are seen in much lower number 
> of nodes. I am testing some applications on a new cluster that I have (dual 
> sockets quad core Barcelona), and my first results are with Fluent new 
> benchmarks. I will have the numbers posted soon, so you all can take a look. For 
> 2 nodes, IB shows an average of 15-20% higher performance then GigE, and this 
> gap gets bigger with cluster size. At 4 nodes the difference was 40-50%. Even 
> more important, 3 nodes results with IB were higher then 8 nodes with GigE, and 
> GigE stop scaling after 3-4 nodes (performance numbers were flat after 3-4 
> nodes). 

Interesting. I am guessing this is with ConnectX adapters and PCIe Gen2. When does
the InfiniBand technology used in this test flatten?  How about the less expensive SDR
technology referred to in Jeff's article?  Can you provide the curves up to 8 nodes for
both IB and GE in this test? 

A quick analysis, limited to this Fluent test, suggests that 4 nodes plus ConnectX 
technology roughly equals 8 nodes plus on-board GE technology.  Can you provide
the system per node price differences?  Then we can rougly determine the cost 
benefit relationship.

Regards,

rbw

--

"Making predictions is hard, especially about the future." 

Niels Bohr 

-- 

Richard Walsh 
Thrashing River Consulting-- 
5605 Alameda St. 
Shoreview, MN 55126 

Phone #: 612-382-4620
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