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Subject: Re: Odd hyperthreading behavior

Author: Vincent Diepeveen

Date: 10:46:51 10/05/03

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On October 04, 2003 at 23:54:43, Jeremiah Penery wrote:

>On October 04, 2003 at 22:27:45, Tom Kerrigan wrote:
>
>>You're right, the #s do work out pretty well, but that must mean both threads
>>are bouncing around different logical processors frequently, otherwise there'd
>>be a disparity in the node counts of each thread. This doesn't seem likely to me
>>but I guess it's not impossible. I wonder if there's a way to keep track of
>>which thread is running on which processor.
>
>The threads really do hop around the processors.  You wrote previously that a
>process should stay on the same processor until 'something odd happens' - in
>other words, until something pre-empts the process.  It's very frequent that a
>part of the kernel, or a service, or something else with default high+ priority
>gets scheduled for some miniscule fraction of time, so it will bump your process
>to another processor.  If you raise your program's priority to realtime and run
>two threads, you should be able to get more stable results in this regard.

There are windows functions to attach a certain process to a certain cpu. Really
nothing new. Was there in NT already years ago.



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