Author: Tony Werten
Date: 09:20:43 03/03/06
Go up one level in this thread
On March 03, 2006 at 09:46:12, Tord Romstad wrote: >On March 03, 2006 at 02:48:04, Tony Werten wrote: > >>On March 02, 2006 at 16:35:17, Robert Hyatt wrote: >> >>>I'll give it a whirl. Less data to copy on parallel splits since each thread >>>needs its own history stuff... >> >>Does it ? >> >>From a clock cycle performance point of view I would agree, locking is to >>expensive. From a search performance pov, I would rather use a "global" table. > >I don't understand either of you. I use a single shared history table, without >locking. I haven't seen this cause any problems, and I don't see why it should. > >What's the problem with a shared history table? Problem is a big word, it probably isn't that bad. Suppose thread 1 want to add 1 to the counter: 1) load memory into register 2) add 1 to register 3) move register to memory If the thread is interrupted between 1 and 3 and thread 2 adds to the same entry, you have lost 1 add. But you're probably right, it certainly isn't as bad as with shared hashtables. Tony > >Tord
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