Hello c-lazor ,
Thank you for joining the Intel communities.
We have not seen this issue, I’m not sure if more customers have similar problems since we have not received this kind of issue, I’m not saying that the issue is not there but I just tested this unit today to check the temperature and usage and I did not see this problem.
Have you try updating the bios, you can download the latest bios version here:
Please see F7 BIOS Update Instructions for Intel® NUC
Try downloading the Intel® Extreme Tuning Utility run it and check the CPU utilization and temperature there when you use a SD card.
I can't help but notice that Ubuntu 15.10 (in title) is a very different OS that the one for Intel® Extreme Tuning Utility. Ivan, did you test on Ubuntu 15.10 or on Windows?
I think this is something to be solved by the Linux/Ubuntu guys, though. ... https://duckduckgo.com/?q=kworker+100
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Yes you are correct I am using Ubuntu 15.10 64 bit. I have tried updating to various kernels up to and including 4.5 with no change regarding this issue. I did make some progress in finding a workaround for the problem that is working for right now.
Here is what I have found:
If I insert the SD card into the on board SD reader kworker uses 100% of cpu 0. This persists even after the card is unmounted and removed. Logging off then back on makes no difference. The only solution is to unmount & remove the card then reboot.
If I open a terminal and enter the following "
tail -n +1 /sys/firmware/acpi/interrupts/*" minus the quotes I find that /sys/firmware/acpi/interrupts/gpe6F has a very high number of 35000 in a short period of time. If I open the terminal and enter "
echo disable | sudo tee -a /sys/firmware/acpi/interrupts/gpe6F" the cpu usage immediately drops down to normal levels.
To make this happen on every boot I opened /etc/rc.local using "sudo nan
/etc/rc.local". Then above the exit 0 line I added the line "echo disable > /sys/firmware/acpi/interrupts/gpe6F". This had taken care of the problem as far as I can tell but I do not know why it is happening to begin with.
I’m sorry I tested it with Windows not with Ubuntu, Intel has not validated using Ubuntu with this unit but you can install Ubuntu almost in every computer.
The latest bios version will fix the issue where inserting a SD card would cause the CPU usage to elevate. You can see the release notes here:
You can download the latest bios version here if you would like to try it: