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High idle cpu even though an app is using 100% and struggling

Hi everyone,


I am currently using a MacBook Pro and an iMac to handle a lot of vector images (trying to arrange them in a big grid). I do this using Inkscape, but when it comes to image analysis I also use Mathematica.


I have noticed a strange behaviour on both machines, with both software. Even though the apps are making use of 100% of cpu (not at the same time), the idle cpu is almost always around 74%. The Mackbook Pro has two cores but I am seeing four columns in CPU usage or history, due to hyperthreading. The first and third column are half way busy, like a little above 50%, and the other two are almost empty (that's when the apps are shown to be using 100% cpu individually).


The only time the idle cpu drops below 50% is when I turn on the machines, i.e. when the system needs more cpu. The overall cpu LOAD in activity monitor has a few spikes then, but when the apps I am using require more power, it never goes above 50% (the load).


I have spoken to Apple support but they couldn't find some other relevant report of this issue. Please note that I am about to take the MacBook Pro for service, because of an email I received saying that the SSDs of this series have been found to be faulty. So when it comes to the laptop, this could be related to this issue. But how about the iMac? It shows the same behaviour and I doubt there's something wrong with its SSD too.


Any suggestions would be greatly appreciated.


Legnahn


=============================

  Model Name: MacBook Pro


  Model Identifier: MacBookPro14,1


  Processor Name: Intel Core i5


  Processor Speed: 2.3 GHz


  Number of Processors: 1


  Total Number of Cores: 2


  L2 Cache (per Core): 256 KB


  L3 Cache: 4 MB


  Memory: 8 GB


MacBook Pro Retina (2015 and later)

Posted on Dec 20, 2018 2:08 AM

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Posted on Dec 20, 2018 3:49 AM

I don't see anything abnormal in what you describe. Your mac is running hundreds of processes at any given point in time, and the OS is responsible for distributing this load among the available cores.

Your mac has two physical cores. An application like Mathematica will spawn several concurrent threads at any point in time, and they may or may not all be assigned to the same core. So it is quite possible that the main calculation task be run in a thread on one core, and several others making use of another core - you really have no control over this (and have no reason to, anyway).


You may open Activity Monitor to get a better idea of what processes are using your CPU resources.



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High idle cpu even though an app is using 100% and struggling

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