Search found 155 matches

by micron
Wed Mar 10, 2010 10:22 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: An easy bitboard optimization
Replies: 6
Views: 1381

Re: An easy bitboard optimization

The measured 10% speedup is for actual search, not some contrived test. My program uses LSB scans only, and rather a lot of of them. I incrementally update attack boards with scan-rich code, and my positional scoring does up to 12 scans. Thus circumstances are favourable for the optimization. Disass...
by micron
Wed Mar 10, 2010 10:22 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: An easy bitboard optimization
Replies: 6
Views: 1381

An easy bitboard optimization

A ubiquitous construct in bitboard programming is while ( bits ) { square = GetLSBit( bits ); //...do something with square... ClearBit( &bits, square ); } ClearBit() is typically a macro or inline. static inline void ClearBit( BitBoard * b, int bitNum ) { *b &= gMaskBitOf...
by micron
Sun Feb 28, 2010 8:08 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: TT hit/miss rates
Replies: 4
Views: 886

Re: TT hit/miss rates

You are right. If the TT is virtually empty, the best policy seems to be 'always overwrite'. I wish I had known this earlier. Replacement strategy becomes relevant when the table fills up, which is likely in, for example, an 11-ply search from the start. The answer to your second question is "yes, i...
by micron
Fri Feb 26, 2010 8:58 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: the difference compiling engines using different progs?
Replies: 12
Views: 1707

Re: the difference compiling engines using different progs?

These results obtained for my program on a Mac may be of interest.

Code: Select all

Nominal 9 ply search from the start position
gcc 4.0 -O3   7.05 s
gcc 4.2 -O3   6.92 s
clang   -O3   6.48 s
clang   -O4   5.95 s
The -O4 option for clang http://clang.llvm.org/ enables link-time optimization.
Robert P.
by micron
Fri Feb 26, 2010 8:32 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: TT hit/miss rates
Replies: 4
Views: 886

Re: TT hit/miss rates

I am trying to see how way off mark I am compared with other engines in the TT hit/miss ratio. From the start position, looking until depth 8, this is what I get Cache usage: hits=16009(16.26%) misses=15367(15.61%) conflicts=67063(68.13%) What are typical ratios? I was interested by you...