Only 2 cpu out of 16 in i7 are being used for heavy task in ubuntu

Adarsh

1/25/24, 7:44 PM

I am using ubuntu 22, with an i7 12th gen gpu with 16gb ram and Nvidia rtx 3060 gpu with 6GB vram.

While doing heavy tasks such as gaming I have observed in the activity monitor that only 2 CPU out of 16 ( mainly cpu5 and CPU 7 ) are being utilized to 100 percent whereas the other CPU hover near to 0.

I have also observed that the graph of CPU 5 and CPU 7 are almost mirror images, if CPU 5 is being utilized then CPU 7 goes down and vice versa, I am not sure why is this happening and why the other CPU is not being utilized.

This is not only limited to gaming though whenever I hear fans running or doing some task such as browsing I observe the similar pattern. I even tried the solution present here but it does not seem to solve the problem I think I am unable to add the image yet because of reputation so giving you guys with the link to image hope this helps

1 + 2

fan

graphics

cpu

ubfan1

1/25/24, 7:53 PM

Just guessing, but your workload is probably single threaded, so can only run on a single CPU at a time, then when the CPU gets hot, the OS switches to another one.

rtaft

1/26/24, 1:18 PM

@ubfan1 I've seen multithreaded code use while loops without a sleep to check states which gets you a single thread that is pegged all the time while the others barely use any because its so fast. But yea, the point is it's about the software, not the OS.

Score:2

Ubuntu

kanehekili

1/25/24, 8:35 PM

To check your cpus install stress:

sudo apt install stress

Then issue the command:

stress -c 16

assuming you have 8 cpus with 16 threads. Check your monitors now - all cpus should be on 100%

End the test with Crtl+c

Since you tested with "games": Applications that render heavily usually pass as much load as possible to your GPU.

+ 2

Adarsh

1/26/24, 5:09 PM

thank you @kanehekili when I run stress -c 16 all the cpu were at 100, so if I get it correctly it all depends on the software and not the OS, so I am just curious are there any other single threaded softwares out there that I can try? cause I am still thinking while running single threaded instead of running any CPU why only 5 and 7 are being used? in the long run wouldn't it result in wear and tear of that specific CPU?

kanehekili

1/26/24, 7:47 PM

Gradle (a tool to build software) is multiprocessing, But all browsers are multithreaded. Depending on your hardware and the graphic load, a lot of the load is passed to the GPU - so your CPU won't have much to do. With games, I assume the latter.

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