[CentOS] system slowdown

Thu May 18 17:04:18 UTC 2017
Pete Biggs <pete at biggs.org.uk>

> kernel: BUG: soft lockup - CPU#5 stuck for 67s! [khungtaskd]
> kernel: BUG: soft lockup - CPU#7 stuck for 67s! [khugepaged]
> These messages started appearing today around 7 AM, which is when
> users started reporting the slowdown. They are still occurring
> periodically and the system is still slow. Are these messages caused
> by the slowdown or are they the reason for it? Are they useful in
> tracking down the problem?

They are what is causing it to appear to run slow.

The soft lockup is when a CPU is spending a lot of time in kernel mode.
The cause can be a number of things, including overloading or a bug in
the kernel - or sometimes a hardware issue.

Are you seeing any other possibly hardware related errors in the logs?

Do you have the 'sensors' package installed and configured - is
everything OK? (An overclocked CPU or a low voltage/bad PSU can cause
this sort of thing.)

Is the system heavily loaded when you get these errors? Not just with
processes, but memory as well. (One of the hung processes is a kernel
paging process.)