Author: Vincent Diepeveen
Date: 04:42:28 04/13/03
Go up one level in this thread
On April 12, 2003 at 23:39:22, Tom Kerrigan wrote: >On April 12, 2003 at 22:44:09, Vincent Diepeveen wrote: > >>On April 11, 2003 at 16:53:59, Tom Kerrigan wrote: >> >>>On April 11, 2003 at 10:58:29, Robert Hyatt wrote: >>> >>>>I have explained "why not" before. >>>> >>>>My configuration is a dual 2.8. I can't remove a CPU because I don't have a >>>>terminator to >>>>stick in the socket. So I am stuck with two. I can enable or disable SMT when >>>>I boot the >>>>machine. >>>> >>>>now tell me how to run the test. Two copies might run on one physical cpu >>>>(using two >>>>logical cpus). Or they might run on two physical cpus. I have no control over >>>>that. And >>>>they will bounce around between processors as they run. >>>> >>>>Your turn. Tell me how to run a valid test and I'll let 'er rip. >>> >>>Actually a friend of mine has access to a P4/3.06 and I ran the test myself. >>>Took less than 5 minutes. >>> >>>I opened two instances of my program and had them search the same position >>>simultaneously and compared their NPS after ~10 seconds. I did this three times. >>>Task Manager showed that both logical processors were pegged. The NPS ratios >>>were: >>> >>>51%-49% >>>49%-51% >>>48%-52% >>> >>>It's pretty darn obvious that HT does not favor one logical processor more than >>>another. (Contrary to Hyatt and Vincent's assertions.) >> >>I do not see why this is contrary to my assumption. What i see is that SMT >>improves nps with say 15%. How that is divided between the 2 processes i didn't >>write down anything about here. > >"with SMT that is not the case. the second cpu in SMT delivers somewhere between >0% and 20%." > >-Tom that was meant not in the hardware form but the actual impact upon software which gets simply between 0 and 20% faster if your program can handle it.
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