On Wed, Aug 6, 2014 at 10:40 AM, Anatol Pomozov <anatol.pomozov@gmail.com> wrote:
Hi
On Tue, Aug 5, 2014 at 4:37 PM, Oon-Ee Ng <ngoonee.talk@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.