Author: Vincent Diepeveen
Date: 09:45:40 09/03/03
Go up one level in this thread
On September 03, 2003 at 12:34:53, Sune Fischer wrote: >On September 03, 2003 at 12:23:08, Vincent Diepeveen wrote: >> >>The only one who you are confusing is yourself. > >Correct, I'm confused why _you_ think threads doing independent searches needs >to communicate all the time. > > >>DIEP runs fine at any latency, but the speedup simply gets a lot less when the >>latency goes up. >> >>There are many practical problems. >> >>You speak about shipping messages. >> >>When are you going to receive them. Check each millisecond? >> >>Or let the OS decide? > >I think I explained this already in other parts of the thread. >You can check as often as you want, it's sending the message that's expensive, >not checking for it. > >>The OS fires at 100Hz, so things like processes that are sleeping because of the >>OS putting them to sleep (when locking and for 600 times they can't get the >>lock) then you have a latency of 10 ms before the process is awake. >> >>You are aware of such problems? > >Yes, but this is concerning spawning and killing searches, not communication >between active search threads, don't confuse the issues. > >>DIEP only can run well parallel at a shitload of cpu's thanks to statistical >>chances that a scenario X doesn't happen much. >> >>That took 1.2 years fulltime work. Still tuning some details. >> >>There is a lot of communication. It is very easy to test this yourself. > >So give me an example, don't blow smoke. ok easy example. Only YBW works well. The other parallel search ideas you can shredder. Everyone has physically found this out. It is the only algorithm which doesn't blow your speedup. Feldmann found out. Hyatt found out. Diepeveen found out. And i bet many others. Of course i tried other ways of splitting. They suck for speedup reasons. They suck terrible, then i say it very politely still. So i also wasted time at finding out that YBW is something you MUST use. I assume you know what YBW is. If not there is plenty of articles describing it. Some are downloadable for free if you are not a member of ICGA journal. I am sure Hyatt has described it as well. So when at 500 cpu's, diep first starts search at 500 Mhz cpu and the other 499 idle. Now i ask you, do you want to let it perform the entire search at 500Mhz, or do you prefer knocking in another 499 cpu's? If so how to do that without a lot of communication? >>Just get a cheap network card. Say 100mbit and connect 2 pc's. Now let them do a >>parallel search. >> >>Please report back to me when you have a speedup > 1.0, because initially you'll >>be slower than 1.0 i bet. > >I bet not ;) Your first year of versions i am pretty damned sure it will be < 1.0 :) I remember paderborn 1999. DIEP when run at Hyatts quad 400Mhz box was 6 times slower than single cpu 450Mhz PII. Of course in those days GCC sucked more ass than it does now, but still factor 6 :) Directly after tournament i found the bugs of course. Too bad it didn't work then. Could have won the tournament. Just analyze the games. >-S.
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