[Beowulf] Three notes from ISC 2006

Craig Tierney ctierney at hypermall.net
Wed Jun 28 15:44:55 PDT 2006

Vincent Diepeveen wrote:
> Woodcrest totally destroys everything in terms of raw cpu performance.
> Not only it clocks nearly 25% higher. According to junior team who used 
> such a system
> from HP (that's their normal sponsor) at world champs 2006 it was giving 
> a 20% higher ipc for their program too.

What do you mean 'clock nearly 25% higher'.  Higher than what?  I had
the impression that the top clock rates of the Woodcrest are dropping 
slightly from the Dempsey numbers.  The machines were just announced, 
the team you refer to has a system already?

Can you describe what program they were running?  What is FP intensive?
Woodcrest has added an additional 128-bit SSE2 register, but no 
additional memory bandwidth to support it.  Double the FP performance is 
nice, but in practice I wonder if I will see even a 5% increase for my 
codes.  The change is nice for linpack (doubles node performance), but 
even the efficiency drops somewhat.

> That's 50% faster than 2.4Ghz dual core opteron.
> Only for those who need latency to the RAM above cpu performance,
> A64-single core with 16GB RAM at each node will be more interesting.
> That's not many applications.
> Of course if you buy something *today* the dual core opteron is the 
> preferred node,
> as woodcrest isn't in the shop yet buyable.
> If your software can work with gigabit ethernet then of course the price 
> per node of an A64 dual core with cheap RAM
> and a cheap mainboard could be more interesting than a faster node 
> that's a little bit more expensive, using DDRII ram.
> So the aspect of cost could be a concern.
> At dual socket level however, the choice is simple. Woodcrest will 
> outgun AMD in a big way.

You are comparing Intel's latest processor (which little or no real 
benchmarks) to AMD's last generation processor.  The next generation AMD 
will include an extra SSE2 register.  AMD still scales much better from 
1 socket to 2 socket (in general of course, your benchmarks may vary) 
and Intel can't touch the > 2 socket market yet.

(Not an AMD fanboy, just someone who appreciates seeing performance of 
real codes than arguing performance based on architecture and 


> Add to that that the new socket from intel is like 125 watts TDP. That's 
> just not normal. That's wasting as much as itanium2!
> Vincent
> ----- Original Message ----- From: "Kevin Ball" <kball at pathscale.com>
> To: "Erik Paulson" <epaulson at cs.wisc.edu>
> Cc: <beowulf at beowulf.org>; "Patrick Geoffray" <patrick at myri.com>
> Sent: Wednesday, June 28, 2006 10:29 PM
> Subject: Re: [Beowulf] Three notes from ISC 2006
>> On Wed, 2006-06-28 at 13:41, Erik Paulson wrote:
>>> On Wed, Jun 28, 2006 at 04:25:40PM -0400, Patrick Geoffray wrote:
>>> >
>>> > I just hope this will be picked up by an academic that can convince
>>> > vendors to donate. Tax break is usually a good incentive for that :-)
>>> >
>>> How much care should be given to the selection of the nodes? Performance
>>> is a function of both the nodes and the interconnect - so while your
>>> test cluster allows for direct comparisons of the interconnects it's 
>>> only
>>> for a cluster of AMD processors, or for Intel processors.
>> Prior to Woodcrest, I would have said AMD 100%.  Now?  Its hard to say.
>> I think AMD nodes will still tend to do better at scaling and show
>> interconnects in a better light than Intel nodes, but Woodcrest
>> performance looks like it may be good enough to at least make things
>> competitive for all but the largest clusters.
>>> I could imagine there would be academic sites that would host this
>>> thing, and possibly even spring for the nodes, provided that the
>>> interconnects were donated and they got to use it when it's not in
>>> use (and probably had some promise that no more than X% of the time
>>> would the cluster be in "benchmark" mode)
>> This is very possible... especially if the benchmarking results were
>> interesting enough to pull some papers out of.
>> -Kevin
>>> -Erik, not legally authorized to volunteer the University of 
>>> Wisconsin to
>>> host any such thing.
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