Author: Robert Hyatt
Date: 07:49:00 07/28/01
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On July 27, 2001 at 16:51:08, Roy Eassa wrote: >On July 27, 2001 at 04:32:48, Dann Corbit wrote: > >>On July 27, 2001 at 04:23:37, Matthias Gemuh wrote: >> >>>Hi Experts, >>>are there any possible conflicts when 2 engines use the same TBS with Ponder ON >>>? >> >>Shouldn't be. Unless someone did something stupid. >> >>They're just reading, after all. I am assuming that you are talking about a >>multiple CPU machine, so that ponder=on isn't pure nonesense. > > >Be careful, Dann. Dr. Hyatt has argued strongly that ponder should always be >on, even with a single CPU. (It seemed counter-intuitive to me too, but you >should check out his recent postings -- over the past couple days, I think.) That is correct. If an engine runs with ponder=on, it will use 1/2 of the cpu while it is thinking, 1/2 while it is pondering, and it will be playing with the time allocation code functioning in the mode it was tested most thoroughly in. The play will be somewhat weaker for both engines. Since the machine will seem to be 1/2 as fast as it really is to either engine. On moves where a machine doesn't predict correctly, 1/2 of the time at least, overall play will suffer. On games where a program does predict correctly > 1/2 of the time, play is not hurt due to the speed issue, and the time allocation will be more accurate unless the program is specifically designed and tested to favor non-ponder time controls. In my case, I _never_ play games with ponder=off. I debug with ponder=off but I never pay attention to how the time is allocated since my only interest there is to get the same search result each time when looking for a problem. By using ponder=off, I can reproduce the same tree each time. With ponder=on, it is nearly impossible to do which makes debugging a pain. One other place to use ponder=off is if you want to do an incredibly deep search by letting the program run a few days. Once it finishes the depth you want, it will stop searching if you have ponder=off. If you don't, it will make the move for that depth, then start pondering and continue to burn cpu cycles which might just be wasting resources.
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