Search found 17071 matches

by bob
Fri Mar 13, 2020 2:41 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Removing Large Arrays
Replies: 36
Views: 6667

Re: Removing Large Arrays

Without demonstration inside the stockfish code, using a profiler to see where the time is really going, the trivial tests are meaningless. When there are a hundred arrays and large data objects all competing for the cache, the code will behave very differently from when things are all sitting nice...
by bob
Fri Mar 13, 2020 2:35 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Removing Large Arrays
Replies: 36
Views: 6667

Re: Removing Large Arrays

I don't know when/if it has changed, but years ago when I worked on the Linux kernel some, Linus had an absolute rule that had to be followed unless an acceptable (to him) justification could be offered. "No single procedure/function can exceed 25 lines of code." The reason came from old display dev...
by bob
Thu Mar 12, 2020 6:56 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Strange sporadic speed limitation in engine running in Linux on Ryzen
Replies: 19
Views: 3427

Re: Strange sporadic speed limitation in engine running in Linux on Ryzen

Two things here. (1) if I am testing, I am going to do my best to make the entire test run at the same constant CPU speed. No turbo/speedstep whatsoever. (2) in a game, I would use whatever provides the best overall average speed. With a chess engine, running multiple cores on a single chip, most li...
by bob
Thu Mar 12, 2020 6:49 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Removing Large Arrays
Replies: 36
Views: 6667

Re: Removing Large Arrays

There is one thing everyone is missing. Have you ever had a case where you removed a bit of code (code that is not even executed during the search) and found that the speed improved. Or got worse? Have you ever added a bit of code (say a couple of checks to do something if a bug you are hunting happ...
by bob
Tue Mar 10, 2020 5:57 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Strange sporadic speed limitation in engine running in Linux on Ryzen
Replies: 19
Views: 3427

Re: Strange sporadic speed limitation in engine running in Linux on Ryzen

Don't know about your processor, but I have had to ALWAYS turn off "turbo-boost" on intel processors. This lets all cores run at the max rated (non-boosted) clock speed so that processors won't change speed during a test. Every high-performance machine we run at UAB has had this disabled.
by bob
Mon Mar 09, 2020 5:46 pm
Forum: Computer Chess Club: General Topics
Topic: mate test positions
Replies: 32
Views: 5057

Re: mate test positions

First problem I encountered was some odd FEN. IE "bm" is normally followed by an actual chess move, not something like "mate in n"
by bob
Sun Mar 08, 2020 8:46 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Very cool bug inside Minic
Replies: 6
Views: 1228

Re: Very cool bug inside Minic

I had one of those "moment" years ago. Was playing GM Dzhindi in a 4 computer vs 4 human round-robin tournament. Crafty had gotten into an easily won ending, and suddenly made two odd piece sacrifices to end up in a won KNN vs KP ending. Fortunately the Nalimov tables were active, which is what led ...
by bob
Sun Mar 08, 2020 8:41 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Strange sporadic speed limitation in engine running in Linux on Ryzen
Replies: 19
Views: 3427

Re: Strange sporadic speed limitation in engine running in Linux on Ryzen

Very first thing. Run "top" and keep it active. See if, during the match, the cpu utilization jumps up due to something in your linux distro. I had this happen to me years ago in Suse, which I always considered to be overloaded/bloated anyway. If you don't want to watch top, you might try this: #!/b...
by bob
Thu Mar 05, 2020 2:13 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Searching fail highs shallower..
Replies: 16
Views: 2579

Re: Searching fail highs shallower..

Can't say what he did/does. I don't do it either. I have a somewhat complex algorithm for allocating time now. Has to do with fail highs / fail lows vs normal search behavior sticking with first move for an iteration (or more). As I mentioned, I ALWAYS resolve the score of the first move before movi...
by bob
Wed Mar 04, 2020 9:19 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Searching fail highs shallower..
Replies: 16
Views: 2579

Re: Searching fail highs shallower..

Back when this was a topic on r.g.c.c, someone mentioned that on a root fail low, they set the iteration counter back to one. After thinking about it, the idea seemed to be that the fail low entry at the root will hang around with a bound lower than at all previous iterations. Which means it will co...