Search found 17071 matches

by bob
Tue Aug 28, 2007 11:29 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

First, I though we were discussing this in the context of a chess engine, not in terms of general-purpose applications? I am not sure what you want to say with this. We are discussing the best way to do paging. For Chess programs you don't want to page at all. So in the context of a Chess program i...
by bob
Tue Aug 28, 2007 3:33 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

The alternative is doing a _ton_ of I/O that is totally unnecessary. I'd rather swap out 2 4K pages out of 64 that were actually modified, rather than all 64 of them. Etc... If writing/reading the 64 pages takes as long, of 1% longer than reading/writing the single page, I would prefer writing the ...
by bob
Tue Aug 28, 2007 3:00 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

What kind of logic is that? If 90% of everything you bring in is nonsense, it doesn't matter at all which page size you use. 256KB pages could only be bad if they would bring in a larger fraction of nonsense than 4KB pages. In particular that applies to the initial page-in, where you would just nee...
by bob
Tue Aug 28, 2007 2:47 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Frustrations of a mediocre chess programmer. What next?
Replies: 34
Views: 15809

Re: Frustrations of a mediocre chess programmer. What next?

PSWBTM does allow you to start from arbitrary positions: you just have to specify a file with the moves leading to them in PGN, or FENs, and your match uses those as initial position. I always run matches from the Nunn positions for testing. If the specified file contains 10 positions, and you ask ...
by bob
Mon Aug 27, 2007 1:21 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

Well, if you could show me a formula that calculates optimum page size from other system parameters, and it would evaluate to 4KB, I would be easily convinced. http://gwyn.tux.org/~balsa/linux/cyrix/wip.html gives a formula: page_size = sqrt (cache_line_size * memory) 64 byte cache line size and 1G...
by bob
Sat Aug 25, 2007 9:07 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

A much more interesting question would be what is the best place for split points. Should they be concentrated at remaining depth =4, or 8, or ~16 ply? I'm glad this kind of discussion is coming up, because I'm at the point where this is pretty much all I have left to worry about (besides a few bug...
by bob
Sat Aug 25, 2007 3:51 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

Then you are not using 256K pages. You are using 4K pages. The O/S has to keep up with them as 4k pages, not 256K as well. Because when we share stuff between different processes (two different users executing the same executable such as the shell, or VI or whatever) the code parts are shared. This...
by bob
Sat Aug 25, 2007 1:52 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: BitBoard Tests Magic v Non-Rotated 32 Bits v 64 Bits
Replies: 36
Views: 24256

Re: BitBoard Tests Magic v Non-Rotated 32 Bits v 64 Bits

I had reported this earlier. Magic was no faster than rotated. I switched because of two things... 1. magic is simpler, and simpler is better as I get older. :) 2. Magic gives you the opportunity to update the occupied_squares and then generate moves easily. To do this with rotated bitboards first r...
by bob
Sat Aug 25, 2007 1:47 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

Been giving SMP some thought. It makes sense to use the extra processors for tree splitting when there is nothing else for them to do. I would think that it would be more efficient and friendlier to the cash if say the evaluation routines and move generators were constructed to be done in chunks by...
by bob
Fri Aug 24, 2007 10:06 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: re-inventing the SMP wheel
Replies: 81
Views: 37358

Re: re-inventing the SMP wheel

You can't mix. How on earth is it going to traverse the page tables when each entry could point to a large page or a small page? You get either/or, but not both. I am not talking about mixing sizes. Just setting different access rights on different 4K pages within a 256KB allocated blok. The page-t...