possible bug in Computing preferences -> use at most X% of CPU time.

Questions and Answers : Unix/Linux : possible bug in Computing preferences -> use at most X% of CPU time.

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vince

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Message 96386 - Posted: 12 May 2020, 8:08:25 UTC

I am currently having to throttle CPU usage to keep temperatures down. (I have another thread open on the temp problem and wont bore you with that).
So, I have been tinkering for days with max CPU frequency at the hardware level, number of cores, percentage, etc.

For reference CPU is FX8350 8 cores, 1 thread per core, 4 ghz.

Since this is my work desktop, I want to try and keep the max frequency at 4ghz so I while working it's nice and responsive.

A while ago I found that running 6 cores at 45% of the time was a sweet spot. Everything was at most points, and lowest overall temp.

Today I found that when I specify 45%, the average CPU that it was actually using was around 6%.
If I changed it to 35% then usage was a steady 35%
If I changed it to 50% then usage was a steady 50%
change it to 45% and it's back down to a steady 6%

Very odd. Has anyone else reported this?
My current workaround is to run 2 cores at full tilt.
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Profile Grant (SSSF)

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Message 96387 - Posted: 12 May 2020, 8:49:17 UTC - in response to Message 96386.  

My current workaround is to run 2 cores at full tilt.
It's generally best to run less cores at full sped than to set "Use at most 100 % of CPU time" to anything other than 100% The smaller you set that percentage, the longer it will take to actually process a Task.
Grant
Darwin NT
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Mod.Sense
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Message 96398 - Posted: 12 May 2020, 15:22:15 UTC

I agree, seems a very odd and unexpected result. Is it possible that you found a sweet spot on a power saver setting or something?

I also agree that running less CPUs at 100% is a better way to achieve the result. Helps improve your memory and L2/L3 cache utilization. Sort of helps the machine concentrate on a smaller number of things.
Rosetta Moderator: Mod.Sense
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Questions and Answers : Unix/Linux : possible bug in Computing preferences -> use at most X% of CPU time.



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