Author: Robert Hyatt
Date: 21:30:15 11/20/01
Go up one level in this thread
On November 20, 2001 at 21:58:57, Slater Wold wrote: >On November 20, 2001 at 21:50:32, Uri Blass wrote: > >>On November 20, 2001 at 15:37:39, Slater Wold wrote: >> >>>On November 20, 2001 at 11:25:50, Gordon Rattray wrote: >>> >>>> >>>>[snip] >>>> >>>>Thanks for the helpful info! >>>> >>>>>This is the speedup I see: >>>>> >>>>>Crafty 1.89x >>>>>Junior 7 1.81x >>>>>Deep Fritz 1.31x >>>>>Deep Shredder 1.81x >>>> >>>>This is a surprising and disappointing efficiency for Deep Fritz. So, when >>>>playing on ICC, do you consider Deep Junior 7 to be your strongest option? I'm >>>>assuming that if you have, e.g. Gambit Tiger, then Junior's SMP capability will >>>>give it a significant edge when using your dual, since GT is non-SMP. >>>> >>>>Gordon >>> >>>I thought so too. Deep Fritz SMP code is broken somewhere. That's why I >>>laughed when I heard it was going to be on an 8-way box. It would have run like >>>crap. Unless Frans fixed it. >> >>The question for the match against kramnik is the speed up that they get on long >>time control and not in blitz. >>I do not know how people got the numbers of speedup for Crafty,Fritz ,Junior and >>Shredder > >A 900mhz 8-way box is not going to be impressive with DF. Not the NPS anyway. > >And those are all MY numbers. Run on my 2x1.4Ghz. > >>I think that the way to compare is comparing times and not nodes. > >I know it's not. You can *NOT* compare solutions with SMP machines. The >branching is SO random, and so unpredicible, that I have found solutions in 10 >seconds and not been able to find the same solution in 10 hours. It's the >beauty of SMP. > >>You need to take a test suite from positions when the program changes it's mind >>after some minutes and comparing times. > >No. Won't prove anything. Say it takes 10 minutes to find on 1 CPU, it might >take 30 seconds to find on 2 CPU's. > >>If the numbers are not based on similiar test then my opinion is that they mean >>nothing. > >They were based on something. Program A does 1M nps with 1 CPU. Program A does >1.81M nps with 2 CPU's. That means Program A's speedup is 1.81. No..No..NOOOOO! NPS has _nothing_ to do with speedup. Here are three example runs... 1cpu: time: 53 nps: 328K 2cpu: time: 28 nps: 626K 4cpu: time: 16 nps: 1162K if you use time to compute the 2/4 cpu speedup, you get 1.89 for 2 processors 3.31 for 4 processors if you use nps, you get 1.90 for 2 processors 3.54 for 4 processors NPS is the wrong thing to use because an SMP program will _always_ search more nodes than a pure sequential program for a given position, except for rare anomalies. IE on a machine with no memory bandwidth bottleneck, Crafty's NPS is roughly 4X faster with 4 cpus, but it averages just over 3x faster if you look at the clock to see how long it takes to find a key move at a specific depth, or how long it takes to complete a search to a specific depth. Ignore NPS and _only_ use the time to solution or time to depth to compare speeds. Anything else will produce wildly wrong numbers. > >>Testing it takes time and you need at least some hours of testing before getting >>an estimate for the speedup (not in blitz). > >These were SEVERAL SEVERAL tests I ran. Positions were usually looked at for no >less than 1 hour. > >>Uri
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