Author: Uri Blass
Date: 23:16:24 07/29/03
Go up one level in this thread
On July 29, 2003 at 23:53:46, Robert Hyatt wrote: >On July 29, 2003 at 22:44:28, Vincent Diepeveen wrote: > >>On July 29, 2003 at 21:43:11, Keith Evans wrote: >> >>>On July 29, 2003 at 20:41:37, Vincent Diepeveen wrote: >>> >>>>On July 29, 2003 at 18:18:31, Keith Evans wrote: >>>> >>>>>On July 29, 2003 at 17:35:01, Vincent Diepeveen wrote: >>>>> >>>>>>On July 29, 2003 at 17:14:52, Keith Evans wrote: >>>>>> >>>>>>>On July 29, 2003 at 17:04:44, Vincent Diepeveen wrote: >>>>>>> >>>>>>>>On July 29, 2003 at 16:13:19, Keith Evans wrote: >>>>>>>> >>>>>>>>>On July 29, 2003 at 16:00:20, Tord Romstad wrote: >>>>>>>>> >>>>>>>>>>On July 29, 2003 at 12:49:49, Keith Evans wrote: >>>>>>>>>> >>>>>>>>>>>You're perft performance seems pretty decent to me. >>>>>>>>>> >>>>>>>>>>Indeed. I just did a similar test with my own program on a Pentium 4 2.4 GHz. >>>>>>>>>>In the position after 1. e4 e5 2. d4 d5, my program generates 30 million moves >>>>>>>>>>per second. I guess I could speed it up somewhat, but I don't think I would >>>>>>>>>>come anywhere close to the speeds reported by Vincent and Angrim. >>>>>>>>>> >>>>>>>>>>My move genererator assigns all moves a move ordering score, and also >>>>>>>>>>determines which moves are checks. It generates legal moves only. >>>>>>>>>> >>>>>>>>>>But anyway, I don't understand why people spend so much time and energy on >>>>>>>>>>micro-optimising their move generators. Despite my slow movegen speed, my >>>>>>>>>>program spends only 1 or 2 percent of its time in the move generator. I >>>>>>>>>>guess most other programmers have similar numbers. >>>>>>>>>> >>>>>>>>>>Tord >>>>>>>>> >>>>>>>>>I'm personally interested in the performance of the move generator in a hardware >>>>>>>>>chess chip where it is a large percentage of the total cycles. If it were only >>>>>>>>>1-2% of the time then I wouldn't be interested. Of course a hardware move >>>>>>>>>generator can generate millions of NPS when only running at say 30 MHz, so it's >>>>>>>>>a totally different animal than a software generator running on a 3 GHz >>>>>>>>>processor. >>>>>>>> >>>>>>>>hardware doesn't work like that. you cannot store the moves. >>>>>>>> >>>>>>> >>>>>>>Huh? (Duh?) Where did I say that it pregenerates and stores the moves? Of course >>>>>>>it generates them incrementally. >>>>>> >>>>>>but i hope you realize how hard it is to order moves when all you have is 1 >>>>>>bound that gives how far the incremental generation is. >>>>>> >>>>>>but if you compare speeds. >>>>>> >>>>>>Say that each move costs 1 clock. that's 30 million moves a second at 30Mhz >>>>>>right? >>>>>> >>>>>>Brutus ran at 2002 WCC at something like 33Mhz. So that's 33 MLN a second. >>>>>> >>>>>>DIEP i generate way more than 33MLN a second at the 1.6Ghz K7 i had back then. >>>>>> >>>>>>At 2.127Ghz it is about 72MLN. this with slow RAM storage. It's probably >>>>>>relatively faster at a P4 generating moves because of the fast L1 cache there >>>>>>and everything runs within trace cache when doing a loop for a few millions of >>>>>>times. >>>>>> >>>>> >>>>>Can you do perft at 72 million NPS? (Actually traverse a tree?) If not then >>>>>you're quoting something different. You could use Chrilly's 7 cycle/node number >>>>>which should include everything to generate, make, and unmake moves. So at 33 >>>>>MHz that would be 4.7 MNPS. >>>> >>>>please do not compare perft with generating moves. >>>> >>>> >>>>perft is generating a NUMBER. not moves. >>>> >>>>do you understand? >>>> >>>>all you need is a number for perft. not moves. >>> >>>If you time perft then you get a node count and a time in seconds, therefore you >>>can get nodes per second out of it. If you want to measure correctness then you >>>can just compare the node count. If you want some measure of performance then >>>you obviously look at NPS. >>> >>>I think that this is obvious. Just search through the CCC archives and look for >>>people trying to optimize the NPS in perft. Not that I'm recommending optimizing >>>for that, but it's been discussed many times. >>> >>>My opinion is that if you're going to quote 72 million NPS in software and try >>>to compare that to a hardware implementation, then the easiest way is to compare >>>using a perft style test. If you're just setting up one position and generating >>>moves from that position repeatedly in a tight loop, then there's really no way >>>to compare that. Plus my belief is that the perft number is more representative >>>of the performance of the move generator under real conditions. >>> >>>Here's some perft output from crafty which I take to be the de facto perft >>>standard: >>> >>>Crafty v19.3 >>> >>>White(1): perft 5 >>>total moves=4865609 time=1.24 >>> >>>So to convert this to NPS 4,865,609 [nodes]/1.24 [seconds] = 3,923,878 >>>[nodes/second] >>> >>>Please explain why that is incorrect? What does diep get for this case? >>>73,000,000 NPS? I find that hard to believe. >> >>you are making a mistake. >> >>you still do not understand what perft is. perft is a number > >Vincent, you need to shut up here. > >Perft is _not_ just a number. It is the _size_ of a tree searched to a fixed >depth, from some specific starting position. There are _no_ transpositions in >some programs. But all programs _could_ use the hash table if they wanted to >avoid generating/tallying a part of the tree that is reached via a >transposition. > >But you _totally_ miss the point. Perft is _not_ a performance benchmark. It >is a _correctness_ benchmark. As usual, you try to corrupt something and use >it in a way it was _never_ intended. I'll be happy to enter a "perft war" >with you if you want. There are plenty of tricks to make mine go faster. But >that wasn't why I wrote it, and it is why I haven't tried to make it faster. > > > > >> you can get it >>faster by adding hashtables and such. it has nothing to do with generating semi >>legal or legal moves at all. it is just creating a number faster. and it's not >>only hashtables. ever thought of how you can speed up perft incredible by using >>an incremental attacktable? >> >>There is no need to generate *any* legal move at all for perft. > >Sure there is. Perft defines a tree for a specific position and search >depth. If you don't generate moves and update the board with them, how >are you going to enumerate that tree and determine its _exact_ size??? You need to generate moves but in the last ply you need only to count them. I think that vincent means to the last ply when he says that there is no need to generate any legal move. Uri
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