Author: Uri Blass
Date: 08:56:29 09/04/02
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On September 04, 2002 at 10:25:38, Robert Hyatt wrote: >On September 04, 2002 at 02:47:20, Uri Blass wrote: > >> >>I here agree with GCP >>If Vincent's target was to convince the sponsor >>not to look at the speedup of crayblitz as real he probably >>suceeded. >> >>He does not need to prove that the results of the >>speed up are a lie but only to convince them >>not to trust the results. >> >>The times and not the speedup are the important information. >> >>Times are calculated first and speedup is calculated only >>later after knowing the times. > >I've said it several times, but once more won't hurt, I guess. > >The original speedup numbers came _directly_ from the log files. Which >had _real_ times in them. The nodes and times were added _way_ later. >Once you have a speedup for 2,4,8 and 16 processors, you can _clearly_ >(and _correctly_) reconstruct either the time, or the nodes searched, >or both. We _had_ to calculate the nodes searched for reasons already given. >It is possible that the times were calculated in the same way. I didn't do >that personally, and without the "log eater" I can't confirm whether it was >done or not. > >If you don't trust the speedups, that's something you have to decide, and it >really doesn't matter to me since that program is no longer playing anyway. In >fact, I don't have any source code for the thing as that was one of the many >things lost when I lost the logs and everything else. > >But, as I said, the paper was about the _performance_. And the speedup >numbers were direct computations from raw data. I consider _that_ to be >the important data presented in the paper, along with the description of how >the algorithm worked. > > > >> >>Usually we tend to trust scientists but if the information >>about times is wrong then it means that >>we cannot trust the other details in the article. > > > >So if the _main_ data is correct, and is then used to calculate something >else, the something-else can't be trusted, and therefore neither can the >main data??? > >Perhaps I am missing something... If the something else(times) was originally used to calculate the main data then there is a problem. The information that was used to calculate the main data is not less important than the main data and if we have not correct information about the information there is a problem to trust the main data(it is clear that we had wrong information about times). Uri
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