Author: Dann Corbit
Date: 17:44:48 02/15/06
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On February 15, 2006 at 20:37:57, Joseph Anthony Merolle wrote: >If you guys recall a while back, I reported my K/ns dropping in games and a team >of us were brain storming what the problem was but nothing ever worked until now >with only one engine shredder 9. It seems I found out what the problem is. My >K/ns remains high so long as you play a move that it expects you to play. >However, when you or another engine plays a move that is unexpected, my K/ns >drops because I believe all the resources are absorbed (hash/memory) into the >line it thinks you should have played in its memory. When and unexpected move >is played most computers will just regroup clear the hash tables and hit high >k/ns and deep plys. However, mine does not until now! I discovered something in >Shredder 9 engine parameters the little check box that says “ Keep hash tables” >by un checking this box my K/ns remains high the whole game and my plys are very >deep as a 3.02 GHz 1g of ram should behave. It will play a lot worse if you flush the hash tables every time. As a test play ten games at 40/2hrs using large hash tables. Try with clearing the hash and with not clearing the hash. Now, to measure the effect look at the depth in plies reached. The NPS figure is irrelevant (hash hits will drop NPS figures quite a bit). You will see that NPS is a bad figure anyway. Set the hash to 0 bytes and the NPS will skyrocket. But the search depths will drop like a stone and you will cost yourself 200 Elo. >My questions is how can I get my others engines such as rebka to do the same >thing or is this not possible? There are plenty of things you can do to make the engines play poorly, like clearing the hash between moves. What you have done is caused the "guessed wrong" behavior on each and every move. You are looking at the wrong measurement. Look at the depth in plies achieved by the search. NPS is a "red herring" for sure.
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