CentOS - Apr 2015 - Centos 7 kworker uses 100% of single core on mulit-core processor usage inquiry

On Mon, Apr 20, 2015 at 09:00:07AM -0400, Martes wrote:
> Greetings again everyone. 
> 
> Can someone please respond to this? 
You just posted yesterday...

Anyway, you didn't give much context.  I can see from a google search
why you provided the interrupts output, but judging from what you
posted, that's not the problem.

Perhaps you have a CPU task that's running at 100%?  Did you try and
run 'top'?

Also, what version of CentOS are you running?  Are you running the
latest kernel?

-- 
Jonathan Billings <billings at negate.org>

Greetings Johnathan.

Thank you for the reply.

I have run top, and iftop, etc...

The only process that is listed is as follows:

Tasks: 272 total,   2 running, 270 sleeping,   0 stopped,   0 zombie
%Cpu(s):  7.1 us, 18.3 sy,  0.0 ni, 73.8 id,  0.7 wa,  0.0 hi,  0.1 si,  0.0 st
KiB Mem : 32679644 total,   402520 free,  9889728 used, 22387396 buff/cache
KiB Swap:        0 total,        0 free,        0 used. 21951812 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
   91 root      20   0       0      0      0 R  94.1  0.0   1540:35 kworker/7:1

This is the only worker that is currently taking up 100% of whatever core it is
on. (Right now it is assigned core number 8)

My kernel is version 3.10.0-229.1.2.el7.x86_64.

I don't really have very much context to provide other than it wasn't a
problem prior to restarting after I installed the new liquid cooler.

If I can provide any further analysis, or information for a more clear view of
the issue, then let me know.

Thanks for getting back a reply.

Respectfully, 

Martes G Wigglesworth

On Mon, Apr 20, 2015 at 11:03:43AM -0400, Martes wrote:
> Tasks: 272 total,   2 running, 270 sleeping,   0 stopped,   0 zombie
> %Cpu(s):  7.1 us, 18.3 sy,  0.0 ni, 73.8 id,  0.7 wa,  0.0 hi,  0.1 si, 
0.0 st
> KiB Mem : 32679644 total,   402520 free,  9889728 used, 22387396 buff/cache
> KiB Swap:        0 total,        0 free,        0 used. 21951812 avail Mem 
> 
>   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
>    91 root      20   0       0      0      0 R  94.1  0.0   1540:35
kworker/7:1
> 
I suggest trying out the suggestions listed here:
https://lkml.org/lkml/2011/3/31/68

In particular, if you look at the PID of the kworker using nearly 100%
of a core, you could run: (using the above output from top)

# cat /proc/91/stack 

And you'll see what function(s) it is running.  This will give you an
idea of what task it is spinning on.

-- 
Jonathan Billings <billings at negate.org>