Kworker and jbd2 constantly writing to hdd

[Jay Aurabind]

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 ?

Someone else has also posted about it in arch linux forum:
https://bbs.archlinux.org/viewtopic.php?id=178632, smelling a kernel
bug. But I dont feel it could be a bug, because some other kernel thread
must be requesting some operation, which could be the reason for a
"generic" ata code to pop up.

I'm concerned because my harddisk heats up unnecessarily (though not
violently), and I never had such a situation while using windows (couple
of years ago). I am a noob when it comes to kernel programming, (just
started ldd3), so please correct me if I'm wrong. Please also suggest
something to fix this issue, or to investigate more into this.


Thanks and Regards,
Jay

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