Author: Matthias Gemuh
Date: 10:59:54 02/03/04
Go up one level in this thread
On February 03, 2004 at 12:49:53, William Penn wrote: >On February 03, 2004 at 11:02:05, Bob Durrett wrote: > >>On February 03, 2004 at 08:09:52, William Penn wrote: >> >>>On February 03, 2004 at 04:32:35, Matthias Gemuh wrote: >>> >>>> >>>> >>>>Zied Haddad seems to be unable to connect to CCC from Tunesia. >>>>He seeks to know whether others have encountered a Shredder 8 problem he has: >>>> >>>>after playing many games in a row without clearing hash tables, Shredder 8 >>>>starts messing and missing even mate in 1, till hash tables are cleared. >>>> >>>>[http://f50.parsimony.net/forum200321/messages/5855.htm] >>>> >>>>/Matthias >>>>(message posted on Zied's request) >>> >>>You may be right. I'm not sure yet, but I will start clearing the hash tables >>>before each analysis and see if it makes a difference. Note that I only run >>>Shredder 8 in infinite analysis mode for a long time to analyze positions. >> >><snip> >>> >>>WP >> >>(1) I read somewhere that it's always a good idea to clear the hashtables >>before starting a new analysis but do not recall the reason. Nevertheless, I >>now always hit that "clear hashtable" button whenever I see it. >> >>(2) The PV for Shredder is total garbage except for the first move and this is >>a known bug in Shredder, acknowledged by it's author. It hopefully will be >>fixed one of these days. The sooner the better. >> >>(3) With some engines, I notice another bug which may or may not be related to >>this one. While doing user-guided infinite analysis, sometimes the nps number >>drops to a tenth of it's normal value. When that happens I cuss a little and >>then save the position, turn off the engine, and then restart it, clearing the >>hashtable. Then the nps goes back to a reasonable value. I do not recall which >>engine does this, but it has to be either Crafty, Shredder, Fritz, Hiarcs, >>Tiger, or Junior since those are the engines I use as CB8 analysis engines and >>for overnight automated game analyses. >> >>(4) I still have not learned how to use Chessmaster for analysis, perhaps >>because I'm getting overly senile. It's a pity that The King is not available >>as a CB8 analysis engine because if it were I would use it often. >> >>Bob D. > >Thanks for the info. Can you tell me what "PV" means? I see it mentioned all the >time but have never run across the definition. > >As for nps dropping drastically to 1/10th of it's normal value... That can >happen in endgames with any engine due to heavy tablebase access, although it's >not usually so drastic. You can tell if that's the case because of constant hard >drive access (the hard drive activity light stays on). I've also seen some >significant dropping of nps with the Shredder 8 Gambit engine, but again not so >drastic, perhaps to 1/3rd of normal value. I haven't seen that happen with the >native Shredder 8 engine, which is usually fairly constant speed in a particular >position. There's also the possibility for the counter in some older engines to >wrap back around to zero when it gets to a certain value, a large number which I >don't recall offhand. That causes a big drop in nps, but it's only artifical - >the speed hasn't actually slowed down. >WP A Principal Variation is (from your posting) this thing : 28.Kf2 f5 29.Ke1 a4 30.Ke2 Kf7 31.g4 fxg4 32.Rc4 dxc4 33.b3 axb3 34.Kd2 bxa2 A dramatical drop in nps during long analysis is often due to counter overflow, especially when programmer mistakenly uses counters of wrong type (e.g. 32 bit counters instead of 64 bit) /Matthias.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.