Author: Robert Hyatt
Date: 11:16:38 09/15/03
Go up one level in this thread
On September 15, 2003 at 13:18:28, Gian-Carlo Pascutto wrote: >On September 14, 2003 at 12:52:54, Sietel Monic wrote: > >>My friend runs dual proccessors using hyperthreading so gets 4 threads, I know >>this is bad for chess. Just dont know why > >This is ok. Running with 2 threads on a dual processor with hyperthreading >enabled is _not_, unless you're running Linux 2.4.x or Windows Server 2003. Linux 2.4.x won't cut it either. I use 2.4.21 and it is _not_ SMT-aware. IE it will certainly recognize 4 processors, but it doesn't realize that if there are just two computational tasks to run, they should be run on two physical processors. 2.4 just runs them on any two logical processors. When the two logical processors are on one physical processor, this performs poorly. Ingo Molnar did a scheduler that addresses this (or maybe Rick did it). And it works well (it has two run queues, one for each physical procesor, rather than four, one for each logical processor.) But that isn't in mainstream 2.4 yet (I have not looked at 2.4.22 closely so it _could_ be there). > >-- >GCP
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