Author: Vincent Diepeveen
Date: 04:44:23 02/25/03
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On February 23, 2003 at 01:38:55, Matt Taylor wrote: DIEP is spinning and locking way way less than Crafty. Note that it is pretty hard to do without spinning under linux. The runqueue fires at 100Hz in linux. So the latency for a thread that doesn't search and normally is doing all kind of stuff is around 10ms under linux. For crafty 10ms latency is too much to wait for a thread to get fired for sure. I guess you didn't try to figure out what the cost of it is, otherwise you would not write such unprofessional comments like below. In DIEP under linux i do not idle either. Of course for me 10ms is too expensive too. Instead i generate a bunch of attacktables instead an idle process doesn't hammer at the same cache line like crafty does. It speeds DIEP up 20% (in nodes a second) at 32 processors when i do not take the 10ms penalty but go for doing something with the registers without hurting shared cache lines (so just local allocated stuff). Under windows the runqueue fires at 500Hz, so that's 2ms latency. Still a lot, but a lot less than 10ms latency. Today i go test what the effect of that is for DIEP. I have no dual Xeon to my avail at the moment to test it though. Must do with a dual K7 and dual P3 and see what generating 600 attacktables (about 0.5 ms at the dual k7) just in local ram is going to give versus using WaitForSingleObject. So for processes that let threads idle instead of letting them spin, that is a complete pathetic idea for realtime environments. >On February 23, 2003 at 00:39:34, Robert Hyatt wrote: > >>On February 22, 2003 at 02:54:21, Vincent Diepeveen wrote: >> >>>On February 21, 2003 at 19:49:04, David Weber wrote: >>> >>>>what chess programs support hyper-threading >>> >>>DIEP, Crafty, Fritz. >>> >>>for fritz it speeds up 10% node count at 4 threads at a dual Xeon 2.8Ghz >>>(compared to HT turned off and 2 threads), but chessbase didn't test yet whether >>>it actually speeds up search depth (according to Mathias who operates fritz >>>here). >>>for shredder it does speed up the node counts but not search depth >>>so it has SMT/HT turned off here at this tournament and runs with 2 threads at a >>>dual Xeon 2.8Ghz here. >> >> >>Did you make the necessary changes to spinlocks and spinwaits??? > >Sorry, can't resist a good laugh! > >"No, they're not out yet!" > >:-) > >-Matt
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