[Beowulf] Intel buys QLogic InfiniBand business

Greg Lindahl lindahl at pbm.com
Fri Jan 27 21:34:17 PST 2012


On Fri, Jan 27, 2012 at 09:24:10PM -0500, Joe Landman wrote:

> > Are you talking about the latency of 1 core on 1 system talking to 1
> > core on one system, or the kind of latency that real MPI programs see,
> > running on all of the cores on a system and talking to many other
> > systems? I assure you that the latter is not 0.8 for any IB system.
> 
> I am looking at these things from a "best of all possible cases" 
> scenario.  So when someone comes at me with new "best of all possible 
> cases" numbers, I can compare.  Sadly this seems to be the state of many 
> OEM/integrators/manufacturers.

The point I've been trying to make for the past 8 years is that one of
the two chip families you're looking at doesn't degrade as much as the
other from the "best of all possible cases" to a real cluster running
a real code.

> In storage, we see small disk form factor SSDs marketed generally, with 
> statments like 50k IOPs, and 500 MB/s.

And if you knew that one family of SSDs had a wildly different ratio
of peak alleged perf to real application performance, would you ignore
that? I suspect not.

-- greg




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