Search found 17076 matches

by bob
Thu Aug 23, 2007 6:10 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 38202

Re: re-inventing the SMP wheel

The math looks tough to me. 16K lines mapping into a set that only holds 16 line, is a 1024 to 1 mapping. Not really. Because 1024 is a large number, randomly assigning the pages becomes the same as randomly deciding per page if it is used or not, with a certain probability. This leads to Poisson s...
by bob
Thu Aug 23, 2007 5:56 pm
Forum: Computer Chess Club: General Topics
Topic: EGTB's accesed from the internet?
Replies: 14
Views: 7627

Re: EGTB's accesed from the internet?

You can easily do that. But the cost is prohibitive, in that the program will play so incredibly weakly because of the internet latency. Currently you do a probe and get an answer back in a few milliseconds. On the internet, multiply that by 100 or 1000, and it would absolutely kill the search spee...
by bob
Thu Aug 23, 2007 1:31 am
Forum: Computer Chess Club: General Topics
Topic: interesting position
Replies: 11
Views: 5071

Re: interesting position

In this game http://www.chessgames.com/perl/chessgame?gid=1441216 there is mention of a sideline analyzed by GM Golubov. The end of the line is this position: [D] 5k1r/r3b2p/p3Qp2/qp1p4/8/2R5/1PP2PPP/4R1K1 w - - here it is said h4 is winning but computers take "several minutes" to see it. I tried A...
by bob
Thu Aug 23, 2007 1:16 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: If You Were Starting From Scratch
Replies: 8
Views: 5011

Re: If You Were Starting From Scratch

l have a good position structure well suited to SMP, I think. I am still not sure how best to handle move history for rep detection across multiple processors. but it seems to be going well. Mark, WOW - big step! Here's what I'd do (actually have done - I seem to have rewrite-titis) when re-writing...
by bob
Wed Aug 22, 2007 8:26 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 38202

Re: re-inventing the SMP wheel

Another way to look at it is this: Suppose the processing of each node causes N cache misses (hash probe included), that are randomly distributed over L2. Then in a 4MB cache, with 64K lines, you need a tree of 64K/N nodes before (on the average) a probed entry is flushed from the cache before the ...
by bob
Wed Aug 22, 2007 8:24 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 38202

Re: re-inventing the SMP wheel

The point is that when you allocate x cache-ways worth of memory as randomly scattered pages, The probability for N items to map into the same cache line has a Poissson distribution P(N) = x^N/N! exp(-x). For x=1 (e.g. 1MB in a 4-way 4MB cache) the probability that more than 4 items map into a line...
by bob
Wed Aug 22, 2007 12:07 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 38202

Re: re-inventing the SMP wheel

Well, like I said, I am doing this so far only for L1, as all frequently used data except the main hash easily fits there (if it is not a P-IV). L1 is indexed by the _logical_ address, not the _physical_ address (although it is physically tagged). Although the memory management could indeed scatter...
by bob
Tue Aug 21, 2007 1:35 am
Forum: Computer Chess Club: General Topics
Topic: EGTB's accesed from the internet?
Replies: 14
Views: 7627

Re: EGTB's accesed from the internet?

I have one. It is nowhere near SCSI. And I do mean _nowhere_ near...
by bob
Mon Aug 20, 2007 10:03 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: How to Best Limit Checks in the Quiescence ?
Replies: 9
Views: 4542

Re: How to Best Limit Checks in the Quiescence ?

I do the same since I extend a check when I give it, rather than when I escape it. I can't get to the q-search in check, although once in the q-search it can certainly happen when a capture gives check.
by bob
Mon Aug 20, 2007 10:02 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 38202

Re: re-inventing the SMP wheel

This is very unlikely. For one, compilers and linkers allocate variables as a contiguous set. they have no reason at all to leave large, unused holes between them. So if your total of global variables / tables does not exceed 1MB, they will all nicely map in one L2 cache way without possibilities f...