Author: Slater Wold
Date: 14:53:41 09/06/02
Go up one level in this thread
On September 06, 2002 at 12:25:37, Robert Hyatt wrote: >On September 06, 2002 at 08:14:31, Slater Wold wrote: > >>On September 06, 2002 at 01:41:25, Dave Gomboc wrote: >> >>>On September 05, 2002 at 22:37:18, Slater Wold wrote: >>> >>>>On September 05, 2002 at 21:33:40, Dann Corbit wrote: >>>> >>>>>On September 05, 2002 at 21:29:09, martin fierz wrote: >>>>> >>>>>>On September 05, 2002 at 21:18:42, Slater Wold wrote: >>>>>> >>>>>>>Any comments/thoughts/ideas/suggestions welcome. >>>>>> >>>>>>great stuff slater! >>>>>>what i'd like to see is not only an average speedup (defined as time ratio, not >>>>>>nps ratio - i think that time ratio is what counts) as you give, but rather a >>>>>>list of all 300 speedups you observed, so we can see how the values are >>>>>>distributed (you gave 2 extreme examples) - or you can just give us the standard >>>>>>error on the speedup. what would also be interesting is if you reran the 2 CPU >>>>>>test (maybe more than once....), and recomputed the average, and looked how >>>>>>variable the average speedup is over such a large number of test positions. i'd >>>>>>think that at least the average should be fairly stable, but even that seems to >>>>>>be unclear... >>>>> >>>>>By what means are you limiting the search? >>>>> >>>>>Did you set time in seconds or depth in plies or what? It will make a very big >>>>>difference on how we might interpret the results. >>>>> >>>>>Hash tables can share hits and mask speedup. >>>>> >>>>>Timed searches can suffer from the same effect. >>>>> >>>>>Depth in ply searches are probably the most reliable comparisons, but it is >>>>>impossible to know which ply level is sensible since some problems may take >>>>>weeks to reach ten plies and others may reach 32 plies in a few seconds. >>>>> >>>>>In short, the real difficulty here is designing the experiment. Quite frankly, >>>>>I don't know the best way to proceed. >>>> >>>>I understand what you're getting out, but I do not agree. Simply because the >>>>definition of "relative speedup" is "the ratio of the >>>>serial run time of a parallel application for solving a problem on a >>>>single processor, to the time taken by the same parallel application >>>>to solve the same problem on n processors". It's all about "run time" and less >>>>about "run parameters". IMO. >>>> >>>>As long as both runs were using the *same exact* settings, I think all would be >>>>fair. >>>> >>>> >>>>Also, I simply used 'st 60' in Crafty. A *lot* of positions were thrown out >>>>because a.) they were solved at root or b.) the search time was less than 60 >>>>seconds. >>> >>>Don't you want to be doing something like 'sd 10' and computing >>>time(2cpu)/time(1cpu)? >>> >>>Dave >> >>*I* don't think so. Because the classic definition of "relative speedup" is >>based on runtime. Not depth. > > >Dave's point is that sd=n is the _easiest_ way to get runtime data. > >Search to a fixed depth on 1 cpu, then to the same fixed depth on 2 >cpus, and you have _perfect_ timing data to compute the speedup... Both >searched to the same depth, traversed the same tree, etc... I don't think so. If you take the position of WAC41 you will see there is a 1.19x NPS speedup. However, there is a 16x speedup to ply 11! Then again, if you take the position of WAC76 you will see there is a 1.62x NPS speedup. However, there is a 1.44x speedup to ply 11.
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