8 CPU and one is at ~100% all the time

Question

With :

Ubuntu Release 12.04 (precise) 64-bit
Kernel Linux 3.2.0-29-generic
Intel® Core™ i7-3635QM CPU @ 2.40GHz × 8

The first CPU is always at ~70%-100% with nothing big running and it is making the fan noisy. I am wondering if it is normal and if not, how can I fix this? Thanks.

Solution

I have done the things described in this post : Why does kworker cpu usage get so high? and it worked for me.

Comments

[taneli]

Click on Processes tab, then View > All Processes, and click on "% CPU", what are the top processes?

[Anshuman]

gnome-system-monitor; firefox; at-spi-bus-launcher; etc They all show 0 % CPU.

[Anshuman]

Hmm, sorry, there is kworker/0:3 in top of all. It use 72%CPU.

[GM-Script-Writer-62850]

check what is running using the top command

[taneli]

Urgh, that is a bit complicated to figure out ... This sister site question has a relevant answer: unix.stackexchange.com/questions/22851/… to figure out the exact culprit, but the short of it is that there's likely a misbehaving driver or hardware. Unless the system is supposed to be doing something heavy.

[Kaz]

Shot in the dark: watch --interval=0.5 cat /proc/interrupts to see if an interrupt is hammering the system.

[Anshuman]

Well, I installed Fedora 18, but I had the same issue. Sometime, CPU was at 70-100%, sometime it was normal. I followed this post : askubuntu.com/questions/176565/… And the first solution seems to work for now.