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Subject: Re: hashing in QS

Author: Gian-Carlo Pascutto

Date: 09:17:59 10/21/04

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On October 20, 2004 at 15:53:00, Gerd Isenberg wrote:

>On October 20, 2004 at 03:39:31, Gian-Carlo Pascutto wrote:
>
>>On October 20, 2004 at 02:27:19, martin fierz wrote:
>>
>>>so i want to store the move itself in the hashtable instead of the moveindex
>>>now, as probably everybody is doing.
>>
>>Naah.
>>
>>>the question i have is this: should i stick
>>>with two separate tables for QS and main search? or should i just use a single
>>>big table (seems more sensible to me). or should i do no hashing at all in QS?
>>>any opinions on this?
>>
>>One table vs two tables seems like a clear case for one table to me (what would
>>two tables gain, except less efficiency?).
>
>hmm... probably reducing latency and/or tlb-misses.
>I guess that is specially an issue with a shared table in a multi-threaded
>environment. Remember Vincent's huge "latencies" with huge tables >= 512MByte.
>If you use that only in main search > 0, it doesn't matter so much.
>
>For qsearch a small (a few 100K) thread-local allways replace table may have
>some advantages - at least in my dumb program ;-)

Well, you need to get two cachelines instead of one. So it's not so obvious to
me that even then it would be better.

--
GCP



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