Author: Robert Hyatt
Date: 19:01:30 06/05/02
Go up one level in this thread
On June 05, 2002 at 13:32:52, Vincent Diepeveen wrote: >On June 05, 2002 at 04:17:12, Bas Hamstra wrote: > >you forget to mention evaluation. Seems you guys forget >that chess is about evaluation of a position. You need >so much system time for SEE, Makemove and unmaking >moves that it seems you simply have *no time* for evaluation! > >If the capturing routine/SEE in qsearch is eating all of your system >time, then my advice is to NOT use a qsearch, but to use an evaluation >that directly estimates what you could possibly lose. Just 1 piece >of course. Remove that from the score then. > >That's a few clocks more and your thing gets a few million nodes a second, >but for sure searches 3 ply deeper. My results here are already well known. Crafty spends nearly 50% of the total time in Evaluate() and its sub-functions. SEE, etc are all very small parts. I see Evaluate range from a low of 33% of total search time to a high of just over 55%. Note that in the profile code you have to look carefully to get all of the individual parts of Evaluate() and not just Evaluate() by itself. > >>On June 04, 2002 at 20:31:41, Robert Hyatt wrote: >> >>>On June 04, 2002 at 18:01:03, Gian-Carlo Pascutto wrote: >>> >>>>On June 04, 2002 at 17:52:47, Dann Corbit wrote: >>>> >>>>>On June 04, 2002 at 16:28:39, Gian-Carlo Pascutto wrote: >>>>> >>>>>>On June 04, 2002 at 16:18:55, Gian-Carlo Pascutto wrote: >>>>>> >>>>>>>Because you are using a processor that is clocked at twice the clock >>>>>>>frequency? Why compare a 1ghz processor to a (nearly) 2ghz processor >>>>>>>and conclude anything about efficiency there? Is there anything that >>>>>>>suggests that the alpha is simply more "efficient"? To justify that >>>>>>>clock frequency disparity? >>>>>>> >>>>>>>A machine twice as fast (clock freq) _should_ perform just as well as >>>>>>>a 64 bit machine at 1/2 the frequency... Less would suggest that the >>>>>>>32 bit machine simply sucks badly. >>>>>> >>>>>>I don't agree with the validity of a clock-for-clock comparison, >>>>>>but if you want to do it anyway, I'll again point to Vincent's >>>>>>numbers: >>>>>> >>>>>>At the same clockspeed, Crafty only gets 33% faster on the 64-bits >>>>>>machine. >>>>>> >>>>>>When you read this, keep in mind that most applications get _more_ >>>>>>than 33% faster on the 64-bits machine. >>>>> >>>>>All the new 64 bit chips in the discussion are pretty much beta stage right >>>>>now. >>>> >>>>Not true for the Alpha. >>> >>>Depends on the alpha being discussed. DEC had processors beyond the 21264 >>>running. Although the 21264 was pretty good. Dann was a bit off on the >>>performance as Tim Mann was running a 21264 at 600mhz and getting right at >>>1M nodes per second. Mckinley is getting 1.5M at 1000mhz, so the alpha might >>>have a bit of an advantage still. but it is pretty small... >>> >>>Mckinley is only available to a select few. 21264's are fairly common. >>>Anything beyond that is not readily available... >>> >>> >>>> >>>>>So, I think that architecturally, it makes good sense to design for a 64 bit >>>>>system right now. >>>> >>>>That makes sense, if the 64 bit design is actually faster than the corresponding >>>>32 bit design (even on 64 bit hardware if you wish). >>>> >>>>The case for bitboards is not clear on that matter. Certainly, if >>>>the speedup over nonbitboards is only 33% they will have a hard time >>>>convincingly beating alternative appraoches even on 64 bit hardware. >>>> >>>>-- >>>>GCP >>> >>>You are assuming that bitboards are _slower_ than non-bitboard programs on >>>32 bit machines. I haven't seen this demonstrated yet. We can always do some >>>sort of a test. IE since the most common move generator issue is "generate all >>>captures" we can try that with bitboard and non-bitboard approaches to see if >>>one is really much better than the other on 32 bit machines. I don't think so >>>myself. I think they are pretty equal due to the multiple pipe issue. >>> >>>But a test could be done to see, since this is the most common thing needed >>>in a chess engine. >> >>That's not a fair test, I think. IMO the most heavily used routines are: >> >>- See() >>- GenCaps() >>- SquareAttacked() >>- Make/Unmake() >> >>You just pick the one in which bitboards is good. In fact it is nearly >>impossible to figure out what's best overall by comparing only parts. What you >>could do though, is generate "profile data" about a search in average middlegame >>positions, and see how many times each of the above functions is being called. >>Then we could turn this into a sort of benchmark: >> >>10.000 * a() >>8.000 * b() >>3.000 * d() >>5000 * c() >> >>and compare times for bitboards and 0x88 to do this. This would at least tell us >>if bitboards is faster *for Crafty*. >> >> >>Best regards, >>Bas.
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