Which "on multiprocessors, use at most" line to use


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Questions and Answers : Preferences : Which "on multiprocessors, use at most" line to use

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Profile Glenn Green
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Message 1449643 - Posted: 3 Dec 2013, 21:40:01 UTC

and why are there two of them. I cannot see the difference... I have a quad core, with hyperthreading. Do I count that as 4 processors or 8? I have an ATI card that can do GPU crunching, and I am trying to decide how many processors or cores to keep free... Does the GPU need an actual core free or is a hyperthread enough?
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Message 1449650 - Posted: 3 Dec 2013, 22:00:22 UTC

Your processor effectively has 8 processors and by default SETI@Home will use them all for "CPU" tasks. That is, by default, it will run 8 tasks on the CPU and one on the GPU.
Not being familiar with the ATI GPUs I can't say if you need to set aside a CPU core or not, but I'm sure someone will be along soon to answer that part of your question.
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Profile Glenn Green
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Message 1449662 - Posted: 3 Dec 2013, 22:48:54 UTC - in response to Message 1449650.

But why the two separate lines in the preferences? They both seem the same, except one uses % and the other is an integer. I have 75% selected now, and am running 6 tasks. I assume that is 3 processors and 3 hyperthreads, but I don't know how to tell for sure.
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Message 1449701 - Posted: 4 Dec 2013, 0:18:12 UTC - in response to Message 1449662.

Yes, ATi users should set aside a CPU core for their GPUs.

There are two separate line items for the same preference because the integer one is for older versions of BOINC (for example, the last version of BOINC that would run on Windows Domain Controllers was v5.10.45 which uses this option).

Newer versions of BOINC (as the preference says, v6.1+) support the percentage preference, so it should be set for newer versions.

Profile Glenn Green
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Message 1449730 - Posted: 4 Dec 2013, 3:01:55 UTC - in response to Message 1449701.

Thanks. 75% runs 6 CPU tasks at a time, and keeps one core (two processors) free for the ATI card. I only see AP units on the graphics card, but I have had several in the past few days...
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Questions and Answers : Preferences : Which "on multiprocessors, use at most" line to use

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