Author: Robert Hyatt
Date: 15:47:44 09/06/02
Go up one level in this thread
On September 06, 2002 at 17:53:41, Slater Wold wrote: >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! > I'm not talking NPS at _all_ here. I am talking about how long it takes to complete depth X with 1 cpu and with 2 cpus. Divide the 2cpu time into the 1 cpu time and that's the number... >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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