Author: Vincent Diepeveen
Date: 12:25:11 12/07/99
Go up one level in this thread
On December 07, 1999 at 14:31:17, Robert Hyatt wrote:
>On December 07, 1999 at 09:02:37, Vincent Diepeveen wrote:
>
>>On December 06, 1999 at 15:33:03, Robert Hyatt wrote:
>>
>>>On December 06, 1999 at 13:00:56, Georg v. Zimmermann wrote:
>>>
>>>>>A thousand fold increase would be
>>>>>what, an additional 6 ply search in the same time?
>>>>
>>>>Lets do some math. 40^x = 1000, 40log 1000 = x, x = 10log1000 / 10log40, x =
>>>>3/10log40 = 3 / 1.5 = 1.9
>>>>
>>>>I think it gets you "1.9 ply" deeper if you do brute force. Now we need someone
>>>>to tell us how much that is if you add HT and other modern wunder drugs.
>>>>But I would be very very suprised if you'd reach +6ply.
>>>
>>>
>>>DB has an effective branching factor of roughly 6, about the same as Cray
>>>Blitz, which didn't use R=2/recursive null move. Log6(1000) is at most 4,
>>>so it would get about 4 plies deeper. Certainly nothing to sneeze at...
>>
>>see different post of me. DB may be happy with a b.f. from 10.33
>>
>>>But then again, this math is really wrong, because for each cpu, DB used
>>>16 chess processors. Each chess processor could search about 2.4M nodes per
>>>second (they used almost 500 for DB2 the last match). With one million
>>>processors, they would then have 16M chess processors, and would be
>>>searching about 40,000,000,000,000 nodes per second. At about 1 billion
>>>(max) for DB2, this would be 40,000 times faster. and log6(40000) is 6,
>>>so they could hit about 6 plies deeper. Very dangerous box...
>>
>>the more processors the smaller the speedup. just attaching all processors
>>to the search might take a few minutes.
>>
>>Note that HSU writes that they got very close to 1 billion positions a
>>second but never hit the magic 1 billion positions a second number.
>>
>>Vincent
>
>
>Sure.... hitting 1B is not easy when you have _just enough_ chess processors
>to peak at 1B. But to hit 1B requires perfect speed-matching between the
>chess processors and the SP, which doesn't happen. I think he said that the
>chess processors were running at about 70% of max speed because of this. And
>he also claims 30% efficiency (in a linear way) in his parallel search. Which
>means that no matter how many processors he adds, he gets about 30% of each one.
>
>As far as branching factor, he uses normal alpha/beta, so I have no idea where
>you would get 10+.
See a post some higher.
axb5 was a fail low. way over 3 minutes.
800M * 180 seconds = 144 * 10^9 nodes.
11th root out of that is 10.33
simple nah?
but the reason why is obvious:
- normal alpha beta without good move ordering is a crime
- no hashtables
- in the normal search DB did a lot of extensions
blowing up the search. extensions especially blow up the
search if you don't nullmove.
- i don't believe his 30% claim unless he was minimaxing.
Vincent
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.