Slashdot Mirror
Big Mac Officially Ranks 3rd
An anonymous reader noted that
according to Wired, it will be announced officially on Monday the Big Mac supercomputer is the third-fastest super-computer. The article also talks about some of the amazing supercomputers in the planning stages. The sort of stuff that will make Big Mac look like that old TI-85 collecting dust in your drawer.
Given the basic benchmarks used to rank supercomputers, could a cluster of loosely coupled machines compete, or is the bandwidth demands for the benchmark set too demanding? I'm just curious how projects like what is detailed at distributed.net compare: 1100 dual-processor macs would be vastly outranked by the hundreds of thousands (or millions) of PCs taking part in distributed processing for various code cracking or cancer curing purposes.
#1 - Apple isn't doing anything here except providing hardware
#2 - Virginia Tech, the school who put it all together, has a very un-catchy name for it
#3 - People, notably tech journalists, have assigned it the "Big Mac" nomeclature
If McDonalds' wants to go after the journalists, they'll run afoul of the U.S. constitution, but not as though that's ever stopped Big Business in the past.
Now to get on with the research. It's a credit to them that this computer got from the drawing board to fruition in the tiny amount of time that it did. It's raised the bar for price/performance in the research computing world and hopefully many less wealthy institutions (I'm looking at UK universities especially here). At the end of the day its about the research they put into it and the results they get out of it.
Run down the list and look at processor counts. We've got 5120 at the top (vector), but number 2 needed 8192 to get the job done. BigMac at #3 drops to 2200 and the processor counts hover in that 2000+ category. Until #19, when Cray's X1 jumps in at 252 processors.
Having a fast computer is cool and all, but if you can do it with 252 CPUs instead of 1024 (#22, P4 2.4), isn't that a win?
Besides, LINPACK doesn't stress interconnect latency and bandwidth, only cache and memory performance. When you run a "real" codes on these Mac/Xeon clusters and get 5% efficiency, suddenly the Earth Simulator (and the small Cray X1's) look good when they blow well past the 50% efficiency mark.
Yes, you're quite right, the networking hardware is important.
But as researched by the VT folk, the G5 is significant: It was cheaper for their needs than the Xeons, Itaniums, and Opterons of similar performance and energy consumption!
So both component choices were critical to their achieving number 3.
GPL Deconstructed
>> VT could have built the cluster using Xeons, Itaniums, or Opterons and arrived at roughly the same level of performance.
This is not true at all. VT clearly has stated in their presentation that G5 has the best performance / price for what they do.
The 1.5 GHz Itanium 2 costs over $3000 per chip, and even the 32-bit Xeon 3.06 GHz is about $1000, while the 2 GHz PPC 970 is about $300 or $400. In addition, VT wants 64-bit chips, so Xeon is a nonstarter.
...another writer claims LINPACK DOES stress latency and bandwidth, so one of you guys has it wrong. The point is, they have a fast supercomputer, TODAY, for under 5 million. And 5% efficiency? Uh, let's wait til they run some actual code before guesstimating.
Never pet a burning dog.
Dig around the Top500 list and you'll see that for this benchmark (LINPACK), Myrinet and Infiniband don't do much better than plain GigE. (Which is one reason why the Cray X1 systems aren't ranked higher).
In fact, there are some nearly-identical setups in which there is no difference between GigE and Myrinet.
LINPACK is a good benchmark for generating big numbers for clusters, but it's a pretty poor supercomputing bechmark in general. The faster your machine can multiply and add fp numbers, the better its LINPACK score. This isn't SPECfp_rate. (Notice I said SPEC rate, not SPEC base).