Author: Ernst A. Heinz
Date: 00:55:31 07/21/98
Go up one level in this thread
On July 20, 1998 at 19:21:27, Dan Newman wrote: >On July 20, 1998 at 17:02:51, Roberto Waldteufel wrote: > >> >>On July 20, 1998 at 15:20:24, Dan Newman wrote: >> >>>On July 20, 1998 at 14:36:12, Bruce Moreland wrote: >>> >>>> >>>>On July 20, 1998 at 14:30:47, Dan Newman wrote: >>>> >>>>>One of the biggest effects I see is that I get a much larger node rate >>>>>the longer I run. If I run a test for 10 s I might get 170 knps. If >>>>>I run for 40 s 200 knps. It does level off of course. I'm using a >>>>>P6/200, so I've attributed this effect to improving branch prediction >>>>>as the code runs. Any ideas? >>>> >>>>Maybe it has something to do with the deeper search having characterstics that >>>>differ from the shallower search. >>>> >>>>bruce >>> >>>I bet that's it or at least a lot of it. The major difference is that >>>the deeper plies will have fewer pieces on average. So move generation >>>will be a little cheaper, a smaller portion of the moves generated >>>will be wasted, and so forth. >>> >>>-Dan. >> >>Have you considered that the deeper iterations contain the most transpositions, >>so you will process more nodes quickly by hash table look-up? I think this must >>surely account for at least some of the difference. >> >>Best wishes, >>Roberto > >I hadn't thought about that either--but I've seen the effect even >without a transposition table. > >Actually, I'm beginning to return to my original guess--I've noticed >this effect when benchmarking the move generator in isolation too, just >generating the same set of moves over and over. The longer the run, >the more move generations per second. I imagine this could be due to >the branch prediction hardware settling into an improved (but probably >not optimal) pattern. Or, it could be the OS doing a lot of stuff >immediately after loading the program in--disk accesses or whatever. >Just one more in a series of quirky, unfathomable computer behaviors. > >-Dan. Or it could be a bug in your calculation procedure which amasses small errors to larger ones over time ... =Ernst=
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