Author: Tony Werten
Date: 23:39:29 08/30/04
Go up one level in this thread
On August 30, 2004 at 17:43:23, Robert Hyatt wrote: >On August 30, 2004 at 17:14:32, Gerd Isenberg wrote: > >>On August 30, 2004 at 16:57:50, Robert Hyatt wrote: >> >>>On August 30, 2004 at 16:39:22, Mark Young wrote: >>> >>>>On August 30, 2004 at 15:33:19, Robert Hyatt wrote: >>>> >>>>>On August 30, 2004 at 14:51:01, Uri Blass wrote: >>>>> >>>>>>On August 30, 2004 at 13:51:48, Robert Hyatt wrote: >>>>>> >>>>>>>On August 30, 2004 at 12:24:54, Volker Böhm wrote: >>>>>>> >>>>>>>>On August 30, 2004 at 10:02:54, Robert Hyatt wrote: >>>>>>>> >>>>>>>>>On August 30, 2004 at 08:30:34, Kurt Utzinger wrote: >>>>>>>>> >>>>>>>>>>On August 30, 2004 at 08:12:52, Jouni Uski wrote: >>>>>>>>>> >>>>>>>>>>>Eine FPGA-Karte untersucht momentan ca. 3 Millionen Positionen/Sekunde. 16 >>>>>>>>>>>Karten machen daher theoretisch 48 MPos/sec. (Donninger) >>>>>>>>>>> >>>>>>>>>>>Jouni >>>>>>>>>> >>>>>>>>>> If Hydra made 48 Mpos/sec this again proves (in comparison >>>>>>>>>> with the 2 Mpos/sec on Quad-Opteron server with 4 CPU's of >>>>>>>>>> Shredder) that the number of pos/sec can't be taken as a >>>>>>>>>> reliable value for the goodness of a chess program. It's >>>>>>>>>> of course simply impossible to compare apples and organes. >>>>>>>>>> Kurt [http://www.utzingerk.com] >>>>>>>>> >>>>>>>>> >>>>>>>>>Don't forget that Hydra ripped Shredder's head off. So the NPS _might_ be >>>>>>>>>significant here... >>>>>>>> >>>>>>>>Didn´t I´ve heard you saying that 10 games are not enough to draw a >>>>>>>>statistically significant conclusion on the playing strength? >>>>>>>> >>>>>>>>Greetings Volker >>>>>>> >>>>>>> >>>>>>>With two _close_ opponents, correct. But if one is seriously stronger, as hydra >>>>>>>appeared to be, 10 games is plenty. >>>>>> >>>>>>We do not know if hydra is seriously stronger. >>>>> >>>>>We have a pretty good clue that it is. It is over 10x faster, potentially, than >>>>>other programs. >>>>> >>>>>1. I first assume that the programmer / designer is no dummy. >>>>> >>>>>2. all else being "equal" 10x faster is a _serious_ advantage. >>>>> >>>>>3. the above two points translate into a signficant strength advantage. >>>>> >>>>> >>>>>> >>>>>>You cannot start by assuming that hydra is significantly stronger when this is >>>>>>the question. >>>>> >>>>>With evidence, you can. IE I can certainly assume that Crafty on an 8-way >>>>>opteron is significantly stronger than Crafty on my dual xeon. >>>>> >>>>> >>>>>> >>>>>>If you see 10-0 you can say based on the result that Hydra is significantly >>>>>>stronger but when you see 5.5-2.5 you cannot claim it based on the result and >>>>>>you only can say that you do not know if it is significantly stronger based on >>>>>>the result. >>>>>> >>>>> >>>>> >>>>>If you only look at the results, maybe or maybe not. But I watched many of the >>>>>games with Crafty analyzing. That tells you even more. >>>> >>>>Common sense should tell us that Hydra is stronger. It should have a big >>>>hardware advantage. I think this is your point, and I agree. But I still need >>>>more data to be sure. Right now there is only a 1 in 6 chance that Hydra is the >>>>stronger program based on the games alone. >>> >>>Where does "one in six" come from? >>> >>>IE >>> >>>1. Hydra is at least 10x faster >>> >>>2. It won three and drew five if I recall. which is 5.5/8.0. which is right >>>at +200 on the Elo scale. >>> >>>Yes the number of games is low, but the 1 in 6 seems very weak. IE when you >>>consider _everything_. And don't forget that older versions (Brutus in >>>particular) played on ICC, and the current version is playing on playchess. >>>There are a lot of games. It is nowhere near invincible. But it is _very_ >>>strong compared to other programs. >>> >>>Of course I am not _sure_. But I an fairly well convinced. :) >> >>Yes, but Hydra had the advantage to prepare and tune againts a public available >>Shredder, while Shredder had not the chance. >> >>Anyway i am curious about Hydra's further speedups, and "fear" they will >>dominate the scene for some time. >> >>Current FPGAs they use, are still not the fastest. >>FPGAs may have more future speedgrowing as general purpose hardware for some >>time. More and "wider" chess "alus" for evaluation purposes. >>PCI express will speedup the hard- software communication. >>Even if it is not efficient, an additional ply in hardware is reasonable with >>respect to the possible PCI bottleneck. >> >>Do you have an idea about the parallel speedup of this 8*2 cluster, about six? > > >I really can't make an educated guess. > >A cluster will be less efficient than a pure SMP box. But to take this in >"pieces" we might get a number that is reasonable. > >IE 8 nodes. I'd think that if it was 4x faster with 8 nodes that would be a >win. Since the nodes have to talk via message-passing, sharing the hash table >will be a problem. 4x faster would be worth doing. > >Inside a node, there are two FPGA boards as I understand this. I don't know how >much of the search is done in one of these FPGA boards, but whatever it is, >there is an efficiency loss with no hashing going on. Of course I don't hash in >the q-search, and I believe Amir has said he doesn't hash in the last normal ply >of his search either, so perhaps this is not a killer. The main problem is that >this hardware apparently has to do a fixed-depth search, which limits split >points and accumulates significant amounts of "idle time" (ie if it is necessary >to only do hardware searches at ply=N, sometimes ply=N is an ALL node and the >parallel search will work well, othertimes it is a CUT node and parallel search >won't work at all. What they lose to deal with this I don't know. But I'd >guess that 1.5x would be a number I would be happy with. Chrilly told me they use a slightly variable depth to solve this. ie Add 1 ply to the hardware search on odd plies (or even ?) en stuff the software search 1 ply earlier to the cards. Tony > >That makes your 6X faster (rather than 16X the theoretical max) a fairly decent >guess, although it _is_ still a guess. But 6x times 3M nodes per second is >still faster than any current programs on 4-way opterons. I've passed that >speed on 8-way boxes (and beyond) but that hardware is pretty rare to come by. >They are no doubt very strong. > > > > >>I have no idea how well this message passing clusters scale with huge number of >>nodes >= 32 or 256,512 or 1024. Vincent was pessimistic about that, iirc. But it >>seems that internode bandwidth and latency has also some potential to become >>faster and faster to make bigger clusters more efficient. >> >> >>> >>> >>>> >>>>> >>>>> >>>>> >>>>>>Uri
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