Author: maria clara benedicto
Date: 11:03:29 09/05/02
Go up one level in this thread
:) On September 04, 2002 at 17:53:24, Robert Hyatt wrote: >On September 04, 2002 at 16:47:50, Gian-Carlo Pascutto wrote: > >>On September 04, 2002 at 12:00:32, Robert Hyatt wrote: >> >>>Have I not said _many_ times that the parallel speedup is a very dynamic >>>value that can change significantly on the same position run multiple times? >>>have I not given you several examples of such? Do you not understand that you >>>can run a test once and get 2.8, and run it again and get 3.1? If you don't, >>>I can't help you at all. >> >>Your problem is that my testing included error analysis (*), and as far >>as I remember (again, dont have the data on this machine), the result >>was *not* compatible with a speedup of 3.1. > >So? Do we have to keep going back to the variability. Did you see the >log file from my 3.1 run? I sent it to vincent. I thought it went to >everybody in the discussion. > >your "not compatible" is _meaningless_. You take that speedup as an absolute >number. I only +wish+ it was so. But it isn't. I posted a single position >yesterday with a 10% variance... I have some that are far worse. Which means >there is no _absolute_ speedup number, like it or not. A speedup number is just >like a FIDE rating. It applies to a particular situation only... > >IE Eugene has posted 4 different tests producing 1.9 on Intel boxes, and >2 tests producing 1.4 on AMD. Even the hardware can change things... > >> >>The speedup for the same experiment *cannot* be two different values that are >>outside each others error margins at the same time. > >Want to bet? The problem is your "error margin" is wrong. Different >positions produce different sorts of speedups... If you want to say I >can't produce 3.1, fine. But I sent the log. Will it be 3.1 the next >time? No idea. Maybe more, maybe less. I'll be happy to post some >positions that show this kind of variance... > > >> >>Your speedup in my test conditions was 2.8 plus or minus something. >>Not 3.1 plus or minus something. > >OK. So what... I supplied raw numbers. We ran the same test on two >different machines, I got 3.0, you got 2.8. You say my 3.0 is outside >the error range? So it is _impossible_ as Vincent would like to say? >Even though the log clearly shows it happened? > >:) > > >> >>(*) Which is missing in your papers *everywhere*. In fact, it's exactly >>this that caused Vincent and me to discover your time numbers were >>questionale. > >It is not "missing". It is discussed often. But trying to define the 'error' >is non-trivial... it is easier to define it for a single position and multiple >runs, than for several positions, one run each. > > > >> >>-- >>GCP
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