Author: Alex Boby
Date: 21:26:18 06/22/99
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On June 22, 1999 at 22:14:08, Robert Hyatt wrote: >On June 22, 1999 at 15:18:17, Alex Boby wrote: > >> >>A couple problems with timing... >> >>1. In my limited spare time I've just done the switch over from depth based to >>time based searching. I am now having difficulties coming up with an algorithm >>to choose the amount of time which should be spent searching for each move. This >>is a trivial task if the time controls are x moves in y minutes but if the time >>controls are simply x minutes for the whole game (like on ICS), then what's the >>most efficient way to use the time? > > >use target=time_left/X, where X is a constant of your choice. 25-30 work >pretty good, which gives a steadily decreasing time per move as time is >burned away... But experiment with X until _you_ are happy with the usage >pattern... > Sounds like a simple yet effective idea. Is there any advantage to using more time in the opening as opposed to the endgame? I was thinking that some kind of more steady approach would be better, or if anything, probably more time should be spent in the middle game. Perhaps I could use some kind of dynamic X? Ahh,.. now I'm just thinking out loud again :). > > >> >>2. I am developing in C under linux and using the clock() command for all >>timings. The problem I have is that when it says that it took, for example, 10 >>seconds to search, it's in actuality more like 25 seconds. At first I thought >>that I had some kind of problem with casting or arithmetic but I checked all >>that. I also examined crafty's code and it seems exactly the same as far as >>usage of clock() is concerned. Then I thought that maybe my clock chip was >>malfunctioning, but if this were the case then my system would not be keeping >>accurate time,... but it is. Therefore I have no idea what the problem could be, >>but it's a pretty significant one as far as I'm concerned. Any ideas? >> >>Much thanks, >>Alex Boby > > > > >There are _two_ times under unix. clock() returns the total cpu time used. >gettimeofday() is used to return wall-clock time, which is more important in >chess. In general, cpu and wall-clock times should step along together unless >your machine is doing more than one computational task... or unless your >program is doing a lot of I/O for some reason... Just 'show thinking' kind of stuff for debugging purposes. I guess clock() is more a profiling tool then and gettimeofday() is used for more practical purposes. btw,.. your paper on book learning in a recent ICCA journal was very informative and interesting for me. I thank you for taking the time and effort. Alex Boby
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