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Big Mac Benchmark Drops to 7.4 TFlops
coolmacdude writes "Well it seems that the early estimates were a bit overzealous. According to preliminary test results (in postscript format) on the full range of CPUs at Virginia Tech, the Rmax score on Linpack comes in at around 7.4 TFlops. This puts it at number four on the Top 500 List. It also represents an efficiency of about 44 percent, down from the previous result of 80 achieved on a subset of the computers. Perhaps in light of this, apparantly VT is now planning to devote an additional two months to improve the stability and efficiency of the system before any research can begin. While these numbers will no doubt come as a disappointment for Mac zealots who wanted to blow away all the Intel machines, it should still be noted that this is the best price/performance ratio ever achieved on a supercomputer. In addition, the project was successful at meeting VT's goal of developing an inexpensive top 5 machine. The results have also been posted at Ars Technica's openforum."
First, from a an Oct 22 New York Times story:
Officials at the school said that they were still finalizing their results and that the final speed number might be significantly higher.
This will likely be the case.
Second, they're only 0.224 Tflops away from the only Intel-based cluster above it. So saying "all the Intel machines" in the story is kind of inaccurate, as if there are all kinds of Intel-based clusters that will still be faster; there is only one Intel-based cluster above it, and with only preliminary numbers for the Virgina Tech cluster at that.
Third, this figure is with around 2112 processors, not the full 2200 processors. With all 1100 nodes, even with no efficiency gain, it will be number 3, as-is.
Finally, this is the a cluster of several firsts:
First major cluster with PowerPC 970
First major cluster with Apple hardware
First major cluster with Infiniband
First major cluster with Mac OS X (Yes, it is running Mac OS X 10.2.7, NOT Linux or Panther [yet])
Linux on Intel has been at this for years. This cluster was assembled in 3 months. There is no reason for the Virginia Tech cluster to remain at ~40% efficiency. It is more than reasonable to expect higher than 50%.
It's still destined for number 3, and its performance will likely even climb for the next Top 500 list as the cluster is optimized. The final results will not be officially announced until a session on November 18 at Supercomputing 2003.
What they're not telling you is that the real reason they are building a supercomputer is because the only copy of the router passwords is GPG-encrypted, and they lost the key.
That 80% efficiency simply sounded too good to be true, and it was.
Now its at 44%. Thats not a small drop, thats a MASSIVE drop.
They didnt predict any loss in going from a small subset to the whole system? Or was it a publicity stunt (we can outperform everyone! our names are __________!)
[I can picture a world without war, without hate. I can picture us attacking that world, because they'd never expect it]
Apparently there are a lot of cases where a MULTIPLY and an ADD do come together like that, but I'm not surprised if LINPACK doesn't consist entirely of those pairs. ;)
The 17.6 TFLOP theoretical peak assumed a perfect case consisting entirely of MULTIPLY-ADD pairs. In a case assuming no MULTIPLY-ADD pairs, the theoretical peak is 8.8 TFLOPs.
7.4 TFLOPs is only 42% of 17.6 TFLOPs, but it's 84% of 8.8 TFLOPs. I suspect the actual "efficiency" of the machine lies somewhere in the middle.
(As for me, I'm happy with just ONE dualie...)
/Watched WarGames too many times as a kid.