Author: Robert Hyatt
Date: 17:37:53 06/05/03
Go up one level in this thread
On June 05, 2003 at 19:21:46, Matthew White wrote: >On June 05, 2003 at 16:02:51, Robert Hyatt wrote: > >>On June 04, 2003 at 23:08:15, Matthew White wrote: >> >>>On June 04, 2003 at 22:24:59, Robert Hyatt wrote: >>> >>>>On June 04, 2003 at 18:32:43, Amir Ban wrote: >>>> >>>>>On June 04, 2003 at 14:54:30, Anson T J wrote: >>>>> >>>>>>Has anyone noticed if you do engine matches with Junior 8 / Deep Junior 8, ZX, >>>>>>YY (any of them). If you set 1 thread per engine (on a dual machine), they share >>>>>>1 cpu with a net cpu usage of 50% !! >>>>>> >>>>>>Deep Fritz 7, Shredder 7 / 7.04 and all other SMP engines I know of don't have >>>>>>this problem. >>>>>> >>>>>>I guess the Junior 8 engines fix the affinity of the single cpu setup meaning in >>>>>>an engine match or tournament they share the same cpu instead of using one each. >>>>>> >>>>> >>>>>Didn't think of this, damn. >>>>> >>>>> >>>>>>Any fixes known? >>>>>> >>>>> >>>>>The problem should come up whenever running one DJ version against another with >>>>>no. of threads set to less than no. of processors. I can't think of any >>>>>workaround. I should get rid of processor affinity in that case. >>>>> >>>>>Amir >>>> >>>> >>>>What's the reason for doing this? The O/S should handle this by itself and >>>>avoid flipping a single process back and forth between physical processors, >>>>without the program itself being involved in the decision... >>> >>>On a Dual-proc HT enabled system, you would want to make sure that your programs >>>were getting 1 "real" CPU each and one "virtual one". I'm not sure that the OS >>>would necessarily behave like that in every case. >>> >>>Matt >> >>Actually you would want two _real_ cpus, not one real and one virtual. >> >>But, in any case, this can't be the issue because how do you _know_ which >>processor is real and which is virtual, when all you know is 0-n??? > >Lower numbers are real, I believe. The point that I was trying to make before is >that rather than giving one engine two real cpus and one engine two virtual >ones, you would want to partition the real and virtual ones equally. Bear in >mind I was merely speculating as to Amir's motives, I don't know for sure. I can >see the reasoning behind your point as well. > >Regards, >Matt I suspect that with Linux, 0 and 1 are two logical processors on one real cpu, same for 2 and 3. That was certainly true a while back but I have not confirmed it on the latest redhat 9 release. But regardless, it is a messy thing to deal with in a program and, in fact, something that probably should not be addressed as it will crush portability.
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