[Beowulf] Register article on Opteron - disagree

Joachim Worringen joachim at ccrl-nece.de
Mon Nov 22 01:18:05 PST 2004

Robert G. Brown wrote:
>   a) It lists identical hardware configurations as many times as they
> are submitted.  Thus "Geotrace" lists positions 109 through 114 with
> identical hardware.  If one ran uniq on the list, it would probably end
> up being the top 200.  At most.  Arguably 100, since some clusters
> differ at most by the number of processors.  What's the point, if the
> site's purpose is to encourage and display alternative engineering?
> None at all.

The list is provided in XML for just this purpose. However, the list is 
designed to show the list of the 500 "fastest" computers - and if many 
systems of the same type are among these 500, it is valid information, 
too, isn't it?

Concerning Geotrace: they propably operate 6 of these clusters 
independendly for some reason - why shouldn't they be allowed to list them?

>   c) It totally neglects the cost of the clusters.  If you have to ask,

First, you'd need to define 'cost'. I.e., how would you take into 
account the fact that some of the computers are built by volunteers w/o 
any effective pay? Does this actually make the computer more 
cost-effective? Or the typically much higher maintenance cost for 
clusters opposed to "big irons" that many sites experience?

> sponsoring institutions are listed).  If they want to do us a real
> public service, they could do some actual computer science and see if
> they couldn't come up with some measure a bit richer than just R_max and
> R_peak....

Do you know Jack Dongarra's 'HPC Challenge' benchmark, and you track the 
discussions on this i.e. on the SC04 panel? My proposal is to make 
inclusion of the HPCC results mandatory for new entries in the TOP500, 
but keep the list ranked by Linpack for consistency with the results 
over time.

Concerning scaling, R_half gives you some impression already (if 
provided - not all sites do so, probably with a reason).

Apart from this, everyone is free to actually introduce a new kind of list.

> Now, with that said (and it needed to be said, it did it did) the only
> thing most real cluster computer buyers care about is price/performance.

I know that at least *some* customers also care for things like 
reliability, features like job migratrion, low maintenance overhead and 
so on, and include this in their discussion. This is reflected by the 
fact that  not everything in the TOP500 is about beowulf-style 
clustering (with the lowest $/linpack-FLOPS ratio). Thus, it might 
actually give a fair view of the $/"user value" - if you also, in some 
way, could filter out the usual political bias towards or against 
certain systems (like, for example, institutions in the U.S. that are 
not "allowed" to buy the sort of computer that solves their problems 
most efficiently).

> SO I'd have to say that I doubt that the authors of the article were
> particularly well informed, and that AMD is likely to be around and
> kicking for a few years yet.  Look, even the Power series hasn't
> disappeared and it has almost no top 500 presence at all, if you
> discount BG itself as IBM showing its marketing clout and finding a use
> for 700 MHz CPUs in Very Large Quantities...

IBM SP (Power Architecture) has 52 Entries - 10% of the list is just a 
little bit different from "almost no top500 presence at all"!? Or did 
you mean PowerPC?


Joachim Worringen - NEC C&C research lab St.Augustin
fon +49-2241-9252.20 - fax .99 - http://www.ccrl-nece.de

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