Author: Robert Hyatt
Date: 09:25:37 09/06/02
Go up one level in this thread
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...
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