(kworker) eats 100% of my CPU or my Mac is running super hot
while doing nothing
This problem usually happens in MacBook (or MacBook Pro),
although it can happen on other machines too.
"kworker" is a placeholder process for kernel worker threads,
which perform most of the actual processing for the kernel,
especially in cases where there are interrupts, timers, I/O,
etc. These typically correspond to the vast majority of any
allocated "system" time to running processes. It is not
something that can be safely removed from the system in any way.
They usually get busy when there are requests from programs to
access disks, send network packets, etc.
Sometimes, something can go wrong that the CPU gets interrupted
very often (a few hundred or thousands per second). When this
happens, kworker gets very busy, the kernel gets very busy, CPU
is occupied, and the machine gets hot. All for doing nothing.
When this happens, the solution is to upgrade the kernel in the
hope that this particular problem is fixed, or do some workaround
to disable the offending interrupt. As far as "upgrade the kernel
goes", this as happened since kernel 3.10 onwards and at the time
of writing, kernel 4.14 (which is 3.34 if Linus didn't rename 3.20
as 4.0) - the problem still happens.
Fatdog has a built-in script do to this. The script examines the
interrupts issued by ACPI, and if the number of interrupts
exceeded a given threshold in a given detection time, it will
disable it. The name of the script is disable-spurious-gpe
This script can also be started at boot. Fatdog has the system
service configured for this, but it is disabled by default. All
you need to do is enable the service from Fatdog Control Panel. If
need be, it can be customised too. The init script is called /etc/init.d/99-disable-spurious-gpe
Please note that ACPI interrupts are there for a reason. If you
disable the ACPI interrupts, some functions may stop working. In
the case of MacBook, gpe06 and gpe07 are the two known problem
case and they don't seem to affect much. On other machines, those
interrupts may provide hooks to generate special ACPI event keys
(e.g. Fn-F1, Fn-F2, etc); and by disabling that you disable the
ability to detect those key combinations as well.
PS: If you run the script and some interrupts gets disabled, you
can re-enable them again by giving this command:
echo enable > /sys/firmware/acpi/interrupts/gpeXX
is the interrupt number you want to enable. If
you want to disable it instead, use echo disable
instead of echo enable