Kworker and jbd2 constantly writing to hdd

[Mulyadi Santosa]

On Fri, Apr 25, 2014 at 1:52 PM, Jay Aurabind <jay.aurabind at gmail.com> wrote:
> Hi,
>
> My kernel is 3.13.0-24, ubuntu 14.04. I have an ext4 root partition, and
> I can see 2 threads (kworker,jbd2) periodically writing to hdd at about
> roughly (1,5) second interval.
>
> I disabled journalling so that jbd2 is gone. Still, the kworker thread
> is bugging me. Is it really necessary for the system to work properly?
>
> cat /proc/<PID>/stack of the kworker is:
>
> [<ffffffff810846f1>] worker_thread+0x1d1/0x410
> [<ffffffff8108b312>] kthread+0xd2/0xf0
> [<ffffffff8172637c>] ret_from_fork+0x7c/0xb0
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> It doesnt make any sense to me.
>
> On tracing this kworker, I found this line:
>
> kworker/u8:1-68    [000] d...  1135.724955: workqueue_queue_work: \
> work struct=ffff8800701e00b8 function= \
> ata_sff_pio_task workqueue=ffff880073e6f600 req_cpu=256 cpu=0
>
>
> So it seems the function ata_sff_pio_task in
> drivers/ata/libata-sff.c#L1343 is being run. Why is it getting called
> periodically? Is it possible to suppress it ?


Could it be a power management system trying to spin down your disk to
save power?

Try to alter the power management variable from your desktop
environment settings. Try to make it less aggresive.


ALso, it could be the I/O scheduler too. Try to switch to noop and see
if it change the situation

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com