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Technology (Apple) Technology Hardware

Big Mac Benchmark Drops to 7.4 TFlops 417

Posted by CowboyNeal
from the number-adjusting dept.
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."
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Big Mac Benchmark Drops to 7.4 TFlops

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  • by mrtroy (640746) on Wednesday October 22, 2003 @03:12PM (#7283289)
    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 __________!)
  • Instant Numbers... (Score:3, Insightful)

    by Dracolytch (714699) on Wednesday October 22, 2003 @03:12PM (#7283297) Homepage
    Not terribly surprising. Much like estimated death tolls for disasters, never believe the first set of benchmarks for a computer. Wait until thorough testing can be done before you start believing the numbers.

    Y'all should know this by now. ;)
    ~D
  • by dbirchall (191839) on Wednesday October 22, 2003 @03:16PM (#7283331) Journal
    A single G5 FPU (each CPU has 2) can do 1 64-bit (double precision) FLOPs per cycle, or 2 if and only if those two are a MULTIPLY and an ADD.

    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...)

  • by ianscot (591483) on Wednesday October 22, 2003 @03:20PM (#7283385)
    Yet another Apple product that failed to save the world. Lately they do nothing but disappoint us. Boo.

    First you have the iTunes store which doesn't do anything but give the average user basically anything he or she might have wanted to have in on online music store. Despite its being free, we're all cheesed off that it doesn't support OGG, or it's meant partly to push iPods (duh), or whatever.

    Now this -- a supercomputer that has, to quote that again, the "best price/performance ratio ever achieved on a supercomputer." But dang it all, it doesn't completely blow away every established precedent -- it's just in the top five on the usual list of comparisons. One more crushing disappointment.

    From Microsoft, we just want products that don't completely ream us. From Apple, we want the entire world to seem a little friendlier and cooler with every product release, every dot-incremenent OS update. They both disappoint us, but the expectations seem a little different...

  • by Durinia (72612) * on Wednesday October 22, 2003 @03:21PM (#7283401)
    On the other side of the issue is that it places 4th in the current Top 500 list, which was released in June. We won't really know where it places on this "moving target" until the next list is released in November.
  • by Carnildo (712617) on Wednesday October 22, 2003 @03:24PM (#7283425) Homepage Journal
    The big difference is that a "supercomputer" is usually heavily optimized towards vector operations: performing the same operation on many data elements at once. Think of it as SIMD (MMX, SSE, etc), only more so. A "supercomputer" would be pretty useless at ordinary tasks such as web browsing or word processing, as those can't be vectorized or parallelized very well. A "supercomputer" might be good as a graphics or physics engine for gaming, but that's sort of like using a cannon to swat a fly: a lot of work for something that can be done with a simple flyswatter.
  • by mfago (514801) on Wednesday October 22, 2003 @03:36PM (#7283541)
    Efficiency is strongly dependent on the interconnect. Does anyone know if the 128 node benchmark (that supposedly showed ~80% efficiency) was run with only one Infiniband switch -- i.e. all nodes connected through only one switch?

    BTW, the performance never was stated to be 17 TF, so it did not drop to 7.4 (or whatever it ends up to be).
  • point missed (Score:2, Insightful)

    by gerardrj (207690) * on Wednesday October 22, 2003 @04:16PM (#7283936) Journal
    Most responses in here are about how the G5 should be performing better, or should have better numbers than the Xenon or Sparc, or whatever.
    What seems to be missing from most of the conversation is that it's not the Mac's that are loosing efficiency per se, it's the network (the interconnects) that is slowing the machine as a whole down. I know little about the LinPac test, but I would assume that it's written to test/stress the entire machine: CPU, disk, memory and interconnects. If the Macs can finish parts of a problem really fast, but can't get new data in to the nodes fast enough, that will casue a tremendous loss in effieciency.
    Perhaps they need a mechanism for buffering new data on the nodes so that incoming and outgoing data can stream as the network is available and keep the CPUs working all the time.
  • by Experiment 626 (698257) on Wednesday October 22, 2003 @05:10PM (#7284539)

    While some people have given the parent a flamebait mod and hostile replies, the poster makes a good (and humorous) point. Apple is not typically thought of in terms best price performance any more than, say, Cadillac is in the car industry. Macs are bought by those willing to pay a premium for that distinct Apple stying, OSX's slick interface with the power of Unix behind the scenes, the "it just works" factor, and so on. Those who don't care about the amenities and just want bang for the buck go for a Dell or eMachines or whatever. I personally find it quite interesting that a company whose image is more luxury than value and whose products are so much newer in this field than the Linux Beowulf clusters is able to achieve such an impressive level of performance for the cost.

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