[arch-general] Help diagnosing kworker 'bug'

[Oon-Ee Ng]

On Wed, Aug 6, 2014 at 10:40 AM, Anatol Pomozov
<anatol.pomozov at gmail.com> wrote:
> Hi
>
> On Tue, Aug 5, 2014 at 4:37 PM, Oon-Ee Ng <ngoonee.talk at gmail.com> wrote:
>> This is after roughly 6-7 seconds, and 65 MB has already been written
>> by that kworker thread.
>
> How long this IO activity takes? Could it be some kind of automatic
> defragmentation or some other internal btrfs background optimization?
> A good idea is to check btrfs changelog for 3.16 kernel release.

It's continuous and ran for at least 2 hours at most.

>
> 'perf' is a great and very powerful tool that allow to debug problems
> like this. Run '# perf top -g -p $PID' and it will show where the
> process spends *cpu cycles*. It should be enough to understand what
> kworker thread does. For all curious minds I highly recommend to read
> this tutorial https://perf.wiki.kernel.org/index.php/Tutorial

Thanks, if my boy gets to sleep early tonight I'll do that.