Author: Vincent Diepeveen
Date: 06:18:42 09/06/02
Go up one level in this thread
On September 05, 2002 at 11:14:17, Rolf Tueschen wrote: >On September 05, 2002 at 10:53:22, Vincent Diepeveen wrote: > >>On September 04, 2002 at 14:29:05, Robert Hyatt wrote: >> >>you get even with fast memory on your quad only a 2.8 speedup >>on average at 30 positions. > >1. May I politely suggest to you that you stop this tradition of writing your >new remarks below the top line of the quotes "someone wrote..."? I write where i want to. and it is obvious because there are no quotes on the left that i write this. >2. Here is a basic question from my ignorance and for all the young readers here >who wouldn't ask such questions which prove that someone hasn't understood >something. > >Could either Bob or Vincent explain why sometimes the duel is about below 2. and >then here above even 2.8 should be nothing special following Vincent? > >What is this number standing for is it about the advantage of a n+1 processor >number "over" n? And second, what is the point of significant advantage? Greater >than 2.? And all what is below 2, this is weak progress? There is 2 speedups a) number of nodes a second. We do not discuss this here b) how much faster a program runs compared to a single processor. We do not discuss a) a lot. In fact a) is something bob doesn't print at all at every ply. He prints it after a search. We discuss here about actual speedup b) : So 4 processors quad xeon 550 is compareable for bob with a 2.8 times single cpu 550Mhz Xeon. >3. Is 2. or 1.97 a factor of time, NPS or what? >4. This split at the root thing, such a refinement I know from forest sciences, >but here, what does it mean, and most of all, how many chapters of CC I'm away >before I could understand such a term? And how does this topic influence the >question of magnitude of advantage through processor number? You see how >confusing that is... The idea is simple. All processors do their part of the job in searching the tree. You'll never understand how it actually is working unless you do it yourself. > >I'm the real ignorant here and I still have the guts to admit it and to ask >these questions. Simply because otherwise I could never hope to improve. > > >Thank you! > >Rolf Tueschen > > > >> >>that's a lot more than a run on 1 position. >> >>>On September 04, 2002 at 14:02:54, Vincent Diepeveen wrote: >>> >>>>On September 04, 2002 at 12:43:37, Robert Hyatt wrote: >>>> >>>>Please run crafty at 16 processors. Fine with me. >>>>Even though it's a different program. I have no problems >>>>with it. >>> >>>And what would be the point? I might give you some 16 processor >>>numbers on a NUMA machine before long. I _might_. >>> >>> >>>> >>>>But rewrite also the article then that it's not a DTS thing, >>>>but a smp_lock thing that doesn't scale above 8 cpu's. >>> >>> >>>Vincent, the smp_lock thing doesn't hurt me thru 16 cpus as I already >>>know. I don't understand why you don't follow this, but in a typical >>>3 minute search, I see numbers like this: >>> >>> time=3:29 cpu=399% mat=0 n=303284136 fh=89% nps=1450k >>> ext-> chk=4663926 cap=1175890 pp=230533 1rep=74539 mate=3299 >>> predicted=2 nodes=303284136 evals=99342268 >>> endgame tablebase-> probes done=0 successful=0 >>> SMP-> split=774 stop=133 data=14/64 cpu=13:55 elap=3:29 >>> >>>That is from a real game played on ICC. >>> >>>Note it only did 774 splits. that is 774 smp_locks. Do you _really_ think >>>that hurts performance? _really_? >>> >>>If so, I have this bridge I need to get rid of... >>> >>>You can say smp_lock is a problem all you want. You can say that it killed >>>you on a NUMA machine all you want. But that doesn't mean it kills _me_ >>>on 8 or 16 processors... >>> >>> >>>BTW I would hate to publish 16 cpu crafty numbers, because that would probably >>>give you _another_ problem to overcome with your "sponsors". :)
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