Author: Ricardo Gibert
Date: 20:22:30 06/05/02
Go up one level in this thread
On June 05, 2002 at 21:53:28, Robert Hyatt wrote: >On June 05, 2002 at 13:24:22, Vincent Diepeveen wrote: > >>On June 04, 2002 at 20:31:41, Robert Hyatt wrote: >> >>No one can buy such a 'common' alpha that gets 1 million nodes >>a second despite what you write. Only Tim who worked with DEC alpha >>in past times had one. So i don't see that as 'common'. >> > >That was a commercially available alpha workstation, based on the 21264 >processor at 600 mhz. That is about as _common_ as you can get. > > >>The production alpha's all are benchmarked at specint and hell slower >>than IA32 processors are. > >What IA32 can do 1M nodes per second? Particularly at 600mhz? VD's posts might be influenced by the gulf in performance between the top athlon specint submission and the top alpha submission: http://www.spec.org/osg/cpu2000/results/res2002q2/cpu2000-20020422-01326.html http://www.spec.org/osg/cpu2000/results/res2001q4/cpu2000-20011022-01046.html where a 1000mhz 21264 alpha is smoked by a 1733mhz athlon in the crafty section of the benchmark. It's about 25% faster. He seems to assume that TM's results can only be explained by the existence of a special version of the alpha CPU being used in TM's test, since it does not jive with the specint submissions. I'm curious about the real explanation for the discrepancy. > > >> >>>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.
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