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