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Subject: Re: choosing target times and probs with clock()

Author: Dave Gomboc

Date: 13:02:29 06/22/99

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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?

Firstly, I find it interesting that you think it's trivial in the first case.
Do you really want to spend the same amount of time on each candidate?

For a sudden death time control, I guess you have to estimate how long the game
is going to last, and dynamically update your time usage as the game continues.

>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?

You can ask the OS about wall-clock time or about process CPU time... lots of
variations.  Advanced Programming in the UNIX Environment is a good book to look
up details on this stuff.

>Much thanks,
>Alex Boby

Dave



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