Author: Christophe Theron
Date: 20:29:05 10/07/99
Go up one level in this thread
On October 07, 1999 at 21:37:54, Robert Hyatt wrote:
>If you were playing automatically on ICC you would see the problem with not
>checking real often. In 1 0 games (game in 1 minute) the target time can
>easily drop down to .1 seconds, or even .01 seconds after a hundred moves or
>so. You'd better check quickly there. :) This is a problem for windows crafty
>users (95/98, not so much NT it seems) as these systems seem to have a very
>inaccurate timing approach to life, making it very tough to move quickly enough,
>for reasons I don't understand (and don't want to understand).
That's a real problem on PC.
The timer clicks 65536 times in 1 hour, which makes something close to 18.2
times per second, or a 0.05s timer resolution.
This numbers come from the prehistoric IBM PC 4.77MHz and have never been
changed in 20 years, for compatibility reasons.
Even Windows programmers did not dare to change this. You have time functions in
Windows, they returns values in milliseconds, but still the resolution is about
0.05s!!!
That's why there is a limit under which you cannot play faster games, because
the timer resolution would force you to play either instantly or in 0.05s, which
makes a big difference when you can compute more than 100000 position per
second.
Personally I think it's not good to play faster than game in 5 on a PC, because
in the endgame the timer resolution in clearly insufficient.
>My favorite debugging test on my linux box is to play crafty vs crafty, 2 cpus
>per program, and play game in 1 second. Cool to watch as it _still_ looks like
>chess, just played impossibly fast. And I have had many games go over 100
>moves...
I can't do that on a PC. In this case I play games with 4 plies deep searches,
which is not the same but runs fast enough to have several games in one minute.
Can be useful to stress-test a program.
Christophe
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